CH. 1 - PRELUDE: BIOCHEMISTRY AND THE GENOMIC...

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BIOCHEMISTRY - TYMOCKZO, BERG, & STRYER 5E

CH. 1 - PRELUDE: BIOCHEMISTRY AND THE GENOMIC REVOLUTION

CONCEPT: WHAT IS BIOCHEMISTRY? ●Biochemistry seeks to answer fundamental questions like “What are we made of?” and “How do we work?”

●Biochemistry: study of structures and ____________ & ___________ processes that occur in living organisms. □ Physical processes: no changes in chemical composition. □ Chemical processes: changes in chemical composition.

EXAMPLE: Physical vs. Chemical Processes Physical Process: Melting/evaporating water: No changes in chemical composition.

Chemical Process: Electrolysis of water: Changes in chemical composition.

●Biochemistry is a multidisciplinary subject (biology, general/organic chemistry, physics, etc.) & all topics are interrelated. □ The interrelated topics make it challenging to present one topic without referring to others. □ There is no universally accepted sequence of topics that suits every course. ●The potential applications of Biochemistry are ENORMOUS! □ Medical □ Industry □ Agricultural □ Technology □ Nutrition □ Life

Solid Ice Liquid Water Gas/Steam

Heat Heat Melting Evaporation

Electric Current

Electric Current



CONCEPT: WHAT IS BIOCHEMISTRY?

PRACTICE: Which of the following is a chemical process? a) Freezing water b) Tearing paper c) Rotating the bonds of a molecule d) Mixing acids and bases

PRACTICE: Which of the following is a physical process?

a) Digesting food in the stomach b) Rusting of iron c) Baking a cake d) A protein chain folding



1)

2)

3)

4)

CONCEPT: CHARACTERISTICS OF LIFE

●There are _______ characteristics shared by all living organisms that distinguish them from nonliving matter.

EXAMPLE: Characteristics of Life

●Viruses are not considered alive.

□ Question: Which characteristics of life do they lack? ___, ___, ___, ___

●All living organisms contain a biological hierarchy of organization:

EXAMPLE: Biological Levels of Organization

●The Biochemical Unity of Life: all living organisms are remarkably similar at the molecular/atomic levels of life.

□ Lots of evidence at atomic/molecular levels support the theory of a common universal ancestor.

Multicellular Organism

• Human

• Leopard

• Whale

Organ Systems

• Cardiovascular System

• Digestive System

• Nervous System

_________

• Heart

• Stomach

• Brain

Tissues

• Muscle

• Epithelial

• Connective

• Nervous

_________

• Myocytes

• Neurons

• Erythrocytes

___________

• Nucleus

• Mitochondria

• Chloroplast

• Plasma/Cell Membrane

Macromolecule

• Proteins

• Carbohydrate

• Lipids

• Nucleic Acids

____________

• Water (H2O)

• Oxygen gas (O2)

• Carbon dioxide (CO2)

Atoms

• Oxygen (O)

• Carbon (C)

• Hydrogen (H)

• Nitrogen (N)

• Phosphorus

Larger Smaller

Biochemical

Unity of Life

Composed of _________: the cell is the basic and most fundamental unit of life.

______________: The capacity to produce more life, either sexually or asexually.

_________: Organisms are not random and are highly organized using simpler atoms to build larger

molecules & structures to survive.

A dynamic ________________: reactions allow for the extraction & transformation of environmentally

acquired energy.

Response to ________________: Can respond to specific triggers from the environment.

_____________: All life contains DNA, the hereditary material which is passed down to future

generations.

Maintain ___________________: Mechanisms for regulating & maintaining/stabilizing their internal

chemistry.

______________: DNA mutations over time lead to adaptation & improved fitness in changing

environments.

Envelope

Capsid

Nucleic Acid

8)

7)

5)

6)



CONCEPT: CHARACTERISTICS OF LIFE

PRACTICE: Which of the following is not a characteristic of life?

a) Ability to reproduce sexually or asexually.

b) Composed of cells.

c) Ability to metabolize oxygen.

d) Maintain homeostasis.

PRACTICE: Indicate which of the following statements is false:

a) Viruses contain hereditary information.

b) Viruses do not have the ability to reproduce without hijacking a host cell.

c) Viruses are composed of cells.

d) Viruses do not need to extract/consume energy from the environment to exist.



Lightning Solar Radiation

Theory #1

Theory #2

Biomolecule Polymers

Membranes & Protocells

Biomolecule Monomers

Protocell Life: First Cell

Protocells Merge

Coding System &

Enzyme-Catalysis System

Coding System, Enzyme-Catalysis

System & _______

_______ System (RNA)

_______-Catalysis System

CONCEPT: ABIOGENESIS

●Abiogenesis is the natural process of the __________ of life & describes how life arose from nonliving, simple molecules.

●Life originated in the oceans of Earth about 3.8 __________ years ago from nonbiological materials.

□ Nonbiological materials (or prebiotic materials): H2, H2O, NH3, CO2, CH4.

●Atmospheric conversion theory: ______ & ___________ converted prebiotics to simple biomolecules.

●Hydrothermal _______ theory: vents on the ocean floors converted prebiotics to biomolecule monomers.

EXAMPLE:

●Question: So how did more complex biomolecules begin to form if living cells were not around yet to produce them?

●The first biomolecules likely ____________ by alignment using the charged mineral surface of objects such as clay.

EXAMPLE:

● Membrane formation enclosed molecules & prevented them from diffusing away, increasing likelihood of interactions.

□ ______________ formed via the hydrophobic effect, an important step for abiogenesis.

EXAMPLE:

●Double Origin Theory: a coding system & enzyme-catalysis developed in __________ protocells & later combined.

●______, not DNA, was likely the first coding material because of its encoding & catalytic abilities.

EXAMPLE:

Prebiotic Materials Biomolecule Monomers

Free Biomolecule Monomers

Biomolecule Polymer

Hydrothermal Vents

*Experimental evidence shows

RNA & other polymers can

polymerize in this fashion.

*Pool of biomolecules

enclosed in lipid membrane

(protocell).

Protocell (Origin #1) Protocell (Origin #2)



CONCEPT: ABIOGENESIS

PRACTICE: Which of the following is not a popular theory for how biomolecule monomers first originated on Earth?

a) Previously assembled biomolecules likely arrived on Earth via an asteroid.

b) The sun and lightning energized the conversion of prebiotics to biomolecules.

c) Hydrothermal vents on ocean floors energized the conversion of prebiotics to biomolecules.

PRACTICE: Which theory relates to abiogenesis?

a) Endosymbiotic theory

b) Double Origin Theory

c) Cell Theory

d) Big Bang Theory

PRACTICE: A) What molecule was likely the first genetic/coding material? Why?

a) Protein

b) RNA

c) DNA

d) Carbohydrates



Nucleotide Monomers Nucleic Acid Polymer

5’ 3’

The Nucleotide

Nitrogenous Bases & Base-Pairing

vs. Comparing DNA & RNA

Strands

Usual Structure/Shape

Pentose Sugar

Nitrogenous Bases

Function

Directionality of Strand

# of Nucleotides

in a Typical Molecule

CONCEPT: NUCLEIC ACIDS

●Nucleic acids are one of the four major biological macromolecules that compose all cells.

●One of the major functions of nucleic acids is to store/encode hereditary information.

□ __________, __________, & __________ are examples of nucleic acids.

●Nucleic acids are polymers of nucleotide monomers & have directionality (5’ end & a 3’ end).

EXAMPLE:

●Nucleotide monomer consists of at least one _________ group, a _______ sugar & a _______________ _____.

EXAMPLE: Comparing DNA/RNA Nucleotides

●DNA & RNA differ in several ways, including the nucleotides they consist of.

●________ different nitrogenous bases are grouped as pyrimidines or purines.

●The nitrogenous bases of a nucleic acid pair via __________ bonds according to Watson & Crick base-pairing rules.

EXAMPLE:

Pyrimidines

Cytosine (C) Thymine (T) Uracil (U) Adenine (A) Guanine (G)

Purines

Pie

____________________ _________ ____________________ _________

Ribose Sugar Deoxyribose Sugar

Phosphate group Nitrogenous

Base Phosphate group

Nitrogenous

Base

A T

G C

Base-Pairing DNA

Strands Oriented in

Opposite Directions:

______-__________

Usually Double-Stranded

Varies greatly

Ribose

A, T, C, G

-Encode Hereditary Info -Catalytic function: Ribozymes

5’ → 3’

(______ -_________ Strands)

Hundreds to Thousands

-Encode Hereditary Info

______________ (Depends on Organism)

A, ___, C, G (Uses U’s instead of T’s)

_________-Helix

________________

(Lacks Oxygen)

Usually ________-Stranded



CONCEPT: NUCLEIC ACIDS

PRACTICE: A) What is the assumed directionality of the nucleotide sequence below? Label the ends of the molecule.

A C G T C T A A A C G G C T A

B) Is the sequence above from a DNA or RNA molecule? How do you know?

C) Write the complementary sequence to the strand below (include the directionality).

A C G T C T A A A C G G C T A

PRACTICE: Which of the following nitrogenous bases is a purine?

a) Cytosine

b) Uracil

c) Thymine

d) Guanine



Monosaccharide Monomers

Monosaccharides

Polysaccharides

Polysaccharides Function

Starch

Glycogen

Cellulose

Chitin

Peptidoglycan

Energy Storage in ___________

Energy Storage in ___________

___________ Cell Walls

___________ ______

(insects, crabs, fungi cell wall, etc.)

_____________ Cell Walls

CONCEPT: CARBOHYDRATES

●Carbohydrates (or____________): sugars composed mainly of carbon, hydrogen & oxygen with a formula of Cn(H2O)n.

●_________________ are carbohydrate monomers & are water-soluble, white, crystalline solids with a sweet taste.

●Carbohydrates function as primary short-term ____________ sources for most organisms.

□ Monosaccharides can repetitively link to form ___________________ polymers.

EXAMPLE:

●Most monosaccharides have several _____________ ________ (-OH groups) & are therefore polyalcohols.

●_______________ (C6H12O6), the most abundant hexose, can be used by most organisms as fuel or to build structures.

●Glucose monomers are linked together via _____________ bonds.

EXAMPLE:

●Starch, glycogen, cellulose, peptidoglycan & chitin are all examples of polysaccharides with varying functions.

●Carbohydrates can be covalently linked to proteins (glycoproteins), lipids (glycolipids), & nucleic acids (nucleotides).

EXAMPLE: Fill-in the chart with the function of each polysaccharide.

Polysaccharide Polymer

Glucose

“-ose” = sugar (ex. Glucose, fructose, sucrose, lactose, hexose, pentose, etc.)

Glycoprotein:

Glycolipid:

Phospholipid

membrane: Protein

Pentose sugar: Deoxyribose

Directionality

Glucose

Glycosidic bond

DNA Nucleotide:



CONCEPT: CARBOHYDRATES

PRACTICE: Which of the following expresses the correct chemical formula of a carbohydrate?

a) C6H14O5

b) C5H10O5

c) C4H10O6

d) C6H12O5

PRACTICE: Which of the following matches the function of the polysaccharide glycogen?

a) Major component of plant cell walls

b) Major component of bacterial cell walls

c) Energy storage in plants

d) Energy storage in animals



Major component of cell/plasma membranes.

Long-term energy storage in plants.

Long-term energy storage in animals.

___________

_

____________

___ Sex hormones, components of plasma membranes

(cholesterol).

Protection, prevention of water loss, beeswax,

earwax.

___________

_

___________

_

___________

_

Phospholipids

Cell Membranes

Membrane Formation

CONCEPT: LIPIDS

●Lipids are a major class of macromolecules that are diverse in structure & function.

□ All lipids are __________________ (water “fearing”), meaning they don’t easily dissolve in water.

□ Lipids include phospholipids, fats, oils, waxes, & steroids.

EXAMPLE:

●Phospholipids are _______________ (contain hydrophilic & hydrophobic parts).

□ Contain a polar, hydrophilic _________ and nonpolar, hydrophobic __________ (hydrocarbon chains).

●Their amphipathic nature allows them to form __________ barriers & compartmentalize the cell.

□ The hydrophobic effect explains how phospholipids form membranes spontaneously in aqueous solutions.

EXAMPLE:

●All cells contain a cell/plasma membrane that separate the inside of the cell from the external environment.

●_________ _______ model: describes a plasma membrane’s fluid nature with embedded components (proteins, etc.)

●Cell membranes are _____-___________ & have many functions (transport of materials & biosignaling, etc.).

□ Typically, only small ___________ molecules are allowed to freely cross the membrane without requiring energy.

Polar / Hydrophilic Head

Nonpolar / Hydrophobic Hydrocarbon Tails

Glycerol

_________ group

Cholesterol

Glycolipid Carbohydrate Glycoprotein

Globular Protein

Alpha-helix Protein Channel Protein Peripheral Protein

Integral Protein

Phospholipid Bilayer

Cell Membrane



CONCEPT: LIPIDS

PRACTICE: Which of the following is incorrectly matched?

a) Oils; short-term energy storage in plants

b) Fats; long-term energy storage in animals

c) Phospholipids; major component of cell membranes

d) Steroids; include sex hormones & cholesterol

PRACTICE: What characteristic do all lipids have in common?

a) Polymers of glycerols & hydrocarbon chains

b) Hydrophilic

c) Hydrophobic

d) Polar

PRACTICE: What types of molecules are able to freely cross a semi-permeable membrane without an energy input?

a) Small, Polar molecules

b) Small, Nonpolar molecules

c) Large, Polar molecules

d) Large, Nonpolar molecules



Amino Acids

Protein Structure

“-ase” = enzyme

(ex. Peptidase)

Enzymes

Oligopeptide

Peptide

Polypeptide

Protein

____ - ____ amino acids

<____ amino acids

>____ amino acids

100’s to 1000’s of amino acids (Includes ___________ form)

Amino acids

Β-pleated

sheets α-helix

α-helices

Β-pleated

sheets

___-terminal

C-terminal

CONCEPT: PROTEINS

●Proteins: one of the four major biological macromolecules that have vast _______________ & _____________ roles.

●Proteins are polymers of ______ _____ monomers, which have _______________ (N-terminal & C-terminal ends).

□ N-terminal has a free amino group and the C-terminal has a free carboxyl group.

EXAMPLE:

●Each amino acid monomer contains common components & a unique __________.

●Living organisms use _____ different amino acids grouped based on their R-groups.

EXAMPLE:

●Proteins can have up to ________ levels of structure: Primary, Secondary, Tertiary & Quaternary levels of structure.

●Several terms refer to amino acid chains that _______ in length: Oligopeptide, Peptide, Polypeptide & Protein.

EXAMPLE: Consider the protein levels of structure below & complete the chart.

●Recall: enzymes are proteins that ____________ (or speed up) other reactions without being consumed by the reaction.

●The reactants (or ____________) fit into the active site of the enzyme to convert them to products.

EXAMPLE:

Amino Acid Structure

Amino Acid Components:

-Central carbon atom (α-carbon)

-Central Hydrogen atom

-Amino group on N-terminal

-Carboxyl group on C-terminal

-Unique R-group

Common to all

Amino Acids

Table of Amino Acids Grouped on R-groups:

Amino Acid Monomers

Protein Polymer

N-terminal C-terminal

Quaternary Protein

Structure: ___________

amino acid chains.

_________ Protein Structure:

Types, quantity & order of

amino acids.

Secondary Protein Structure:

___-helices or ___-sheets. ___________ Protein

Structure: Overall 3D shape.



CONCEPT: PROTEINS

PRACTICE: Which of the following is not a component of an amino acid?

a) Peptide

b) α-carbon

c) Amino group

d) Carboxyl group

PRACTICE: Which level of protein structure corresponds to the formation of α-helices and β-pleated sheets?

a) Primary

b) Secondary

c) Tertiary

d) Quaternary

PRACTICE: Fill in the blanks: Enzymes __________ chemical reactions _________ being consumed by the reaction.

a) Speed-up ; while

b) Slow-down ; without

c) Catalyze ; without

d) Inhibit ; while



Domains of Life

CONCEPT: TAXONOMY

●Taxonomy is the branch of science that _________________, identifies & properly names living organisms.

●There are ________ biological classification categories used to identify all life.

EXAMPLE:

●Bacteria & archaea are single-celled ________________ organisms because they lack a membrane-bound nucleus.

□ Bacteria most closely resemble the first cells (less divergences in evolutionary tree).

□ Archaea, such as _____________ & thermophiles live under intense conditions.

●Eukarya: cells with a membrane-bound nucleus & include all multicellular organisms & single-celled________________.

EXAMPLE:

●Prokaryotic & eukaryotic: broadest & most distinct groupings of all life. Let’s compare and contrast!

EXAMPLE:

Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species.

__ear __ing __hilip __ame __ver __or __reat __oup. Acronym:

Most Inclusive Least Inclusive

Three Domains of Life

Past Present Time

Eukaryotic

______________

First cell

Eukarya



CONCEPT: TAXONOMY

PRACTICE: Which of the following are correctly listed from least inclusive to most inclusive?

a) Domain → Kingdom →Phylum →Class →Order

b) Domain → Kingdom → Class →Phylum →Order

c) Species → Genus → Family → Order →Class

d) Species → Genus → Family → Class →Order

PRACTICE: Which of the following statements is generally considered true for both prokaryotes and eukaryotes?

a) Both have cells with nuclei.

b) Both have cell walls.

c) Both have circular DNA

d) Both have ribosomes & plasma membranes



Translation

(Ribosomes)

Cytoskeleton

Mitochondria & chloroplasts are

relevant organelles we discuss in

the endosymbiotic theory topic.

Ribosomes

______

_________

_____

____________

_____

_____

(____ Stores/protects DNA. Controls nuclear

transport.

Studded with ribosomes, modifies & helps

proteins fold.

Detoxifies the cell.

Makes carbohydrates/lipids.

Modifies proteins/lipids to ship to final

locations.

Barrier controlling transport into & out of the

cell.

Membrane bubbles that transport & fuse

with membranes.

Vesicle with digestive enzymes that

breakdown & recycle things.

Lysosome

Inside

Cell

Outside Cell

CONCEPT: CELL ORGANELLES

●All cells contain organelles (“organs of cells”): subcellular _________ or components with specialized functions.

●Eukaryotic cells contain several membrane-bound organelles, whereas prokaryotic cells do not.

□ Many membrane-bound organelles of eukaryotes are part of the _________________ system.

□ The endomembrane system functions include modifying, transporting, & ________________ cellular materials.

EXAMPLE:

●All cells contain _____________ that are directly involved in the process of _______________ (protein synthesis).

●Ribosomes have two subunits (________ & ________ subunit) and are a mixture of ribosomal RNA (rRNA) & proteins.

□ Eukaryotic cells have larger ____ ribosomes (60S large subunit & a 40S small subunit).

□ Prokaryotic cells have smaller ____ ribosomes (50S large subunit & a 30S small subunit).

EXAMPLE:

●Consists of _________ & intermediate filaments as well as _________________.

●Functions include providing cell-shape, movement, transportation, & signaling.

EXAMPLE:

Eukaryotic Ribosome Ribosomal Subunits

Ribosomal Subunits



CONCEPT: CELL ORGANELLES

PRACTICE: Which of the following contains an incorrect match of the organelle function/description?

a) Ribosomes: conduct the process of translation

b) Rough Endoplasmic Reticulum: lipid synthesis

c) Smooth Endoplasmic Reticulum: alcohol/chemical detoxification

d) Lysosome: specialized vesicles with digestive enzymes

PRACTICE: Which of the following contains a correct match?

a) 80S: Eukaryotic large ribosomal subunit

b) 60S: Prokaryotic large ribosomal subunit

c) 40S: Eukaryotic small ribosomal subunit

d) 70S: Eukaryotic large ribosomal subunit



Host Cell

Aerobic

bacterium

Mitochondrion

Mitochondrion

Cyanobacterium Chloroplast Plant Cell Plant

Animal Cell Animal

Supporting Evidence

Mitochondria

Protein that makes ATP

(ATP Synthase) Chloroplasts

___________+ + +________

Mitochondria

Chloroplast

Granum

CONCEPT: ENDOSYMBIOTIC THEORY

●The endosymbiotic theory: mitochondria & chloroplasts were once independently living ___________.

●~1.5 __________ years ago, an aerobic bacterium was engulfed by an anerobic host cell, making a symbiotic relationship.

□ Over time, the aerobic bacterium lost many genes/abilities & developed into today’s ________________.

□ Photosynthetic Cyanobacterium were engulfed by a host cell & over time, evolved to the ________________.

EXAMPLE:

●Mitochondria & chloroplast have many similarities to prokaryotes:

□ Both have: 1) small circular DNA, 2) 70S ribosomes, 3) replicate via _________ ________.

●Mitochondria & chloroplast both have a __________ membrane that differ from each other.

●Function: produce ATP (energy for a cell) via ______________ energy metabolism.

●Vary in shape & have their own DNA that is independent of the nuclear DNA.

□ Have an outer & an ________ membrane, which is highly folded into cristae to increase surface area.

●Location of major processes of _________ respiration, like the Citric Acid Cycle & electron transport chain.

EXAMPLE:

●Function: perform _______________ to produce chemical energy from ________ energy.

EXAMPLE:

Ribosomes Matrix Outer

membrane Inner

membrane

Intermembrane Space Cristae

DNA

C6H12O6 + 6 O2 6 CO2 + 6 H2O + ATP Cellular Respiration

Outer membrane

Thylakoid

Stroma

6 CO2 + 6 H2O + Sunlight C6H12O6 + 6 O2

Photosynthesis

Inner membrane

Oxygen

gas

Carbon

Dioxide Water



CONCEPT: ENDOSYMBIOTIC THEORY

PRACTICE: According to the endosymbiotic theory, which of the following is likely the ancestor of the mitochondria?

a) Aerobic eukaryotes

b) Aerobic bacteria

c) Anaerobic bacteria

d) Cyanobacteria

e) Chloroplasts

PRACTICE: What is the primary purpose of cristae in the mitochondria?

a) Provide a large surface area for chemical reactions

b) Prevent the mitochondria from folding onto itself

c) Protect the mitochondrial DNA

d) No purpose has been identified yet



RNA-DNA

hybrid region

Free RNA nucleotides

RNA nucleotides being added to the 3’ end of the RNA

Unwinding of DNA

RNA Polymerase

mRNA

5’

3’ 3’

Coding Strand

Template Strand

Product Formed

Macromolecule Change?

Major Enzyme/Structure

Location

Transcription

Translation

Transcription vs. Translation

EXAMPLE: Use the genetic code to fill-in the blanks:

Cytoplasm

RNA Polymerase

Yes.

Nucleic acid → Protein

____

Nucleic acid → Nucleic Acid

CONCEPT: CENTRAL DOGMA

●Casually refers to both the processes of __________________ & __________________.

□ Transcription: builds ________ using ________ as the coding template.

□ Translation: builds ___________ using the encoded messages of _________.

●Central dogma of molecular biology directly refers to the _____________ flow of biochemical info from DNA to protein.

●DNA is replicated & RNA is ______-transcribed into DNA, but transfer of nucleic acid info to protein is irreversible.

EXAMPLE:

●Transcription uses an enzyme called _______ polymerase, which produces a messenger RNA (or mRNA).

□ RNA molecules built from the ____ to the ____ end by aligning free RNA nucleotides on a DNA template.

□ RNA molecules have same sequence as the _________ DNA strand (except replacing T’s with U’s).

EXAMPLE:

●Translation uses ________________ & specialized RNA called __________ RNA (or tRNA).

□ Ribosomes read the mRNA strand in 3-nucleotide “chunks” called ________ (interpreted with a genetic code).

□ tRNAs pair with ______ _______ & contain ______-codons that are complementary to the mRNA codons.

●Let’s compare/contrast transcription & translation:

RNA Molecule

5’ to 3’ Direction of Synthesis

Genetic Code

__________

__________

_______

______-transcription

What’s the RNA sequence?

G G A T C

What’s the template strand sequence? ____ ____ ____ ____ ____

Amino acid Amino acid

tRNA

Anticodon

Large Ribosomal

Subunit

Small Ribosomal

Subunit

5’ 3’

Codon … AUGUGGUUC … mRNA

UAC

_ _ _

Met

___

RNA Polymerase Movement

Rewinding of DNA

5’

5’

Fir

st L

ette

r o

f C

od

on

Second Letter of Codon

Th

ird L

etter of C

od

on

tRNA

U C A G

U

C

A

G

Ribosome movement



CONCEPT: CENTRAL DOGMA

PRACTICE: What is the central dogma of molecular biology directly referring to?

a) Unidirectional Translation

b) Multidirectional Translation

c) Unidirectional Transcription

d) Multidirectional Transcription & Translation

PRACTICE: Consider a DNA template strand of the following sequence: 5’-A C T G C C A G G A A T-3’.

A) What is the sequence of the corresponding DNA coding strand? Include directionality.

DNA Template Strand: 5’-A C T G C C A G G A A T-3’.

DNA Coding Strand:

B) What is the sequence of the corresponding mRNA strand? Include directionality.

mRNA Strand:

PRACTICE: Consider a DNA coding strand with the following sequence: 3’-C T T C A T A G C T C G-5’.

Use the genetic code to determine the corresponding amino acid sequence of the translated protein.

DNA Coding Strand: 3’-C T T C A T A G C T C G-5’

mRNA Strand:

Protein Sequence:



Functional Groups:

Linkages:

Ether ____________ _________________ Phosphoanhydride

____________ Sulfhydryl group ____________ Carboxyl group _____________ Phosphate group Methyl group

Functional Groups in Biomolecules

Essential Elements of Life

2) 1) 3) 4)

CONCEPT: FUNCTIONAL GROUPS

●Functional groups: portions of a molecule that are abundant in biomolecules & tend to be ___________.

□ Typically extend off of the carbon backbone of a molecule.

●_____________: particular bonding arrangements of atoms that can be used to link different kinds of molecules.

EXAMPLE: Label the functional groups & linkages below:

●Certain functional groups & linkages appear frequently in specific types of molecules.

1) Amino acids & proteins have _____________ groups & _____________ groups.

2) Carbohydrates tend to have an abundance of ____________ groups and _________ linkages.

3) Lipids vary greatly in structure, but fatty acids typically have ____________ groups.

4) Each nucleotide in a nucleic acid molecule has _________________ linkages.

EXAMPLE:

●Of all the known elements, only a small subset is found in living organisms.

●~97% of the mass of most life is composed of Carbon, Hydrogen, Nitrogen, Oxygen, Phosphorus & Sulfur (CHNOPS).

●23 other elements called __________ elements appear in small amounts but are still required for life.

□ Include 5 essential ions: Na+, Cl-, K+, Ca2+, Mg2+

EXAMPLE:

Amide linkage



CONCEPT: FUNCTIONAL GROUPS

PRACTICE: Identify and label the functional groups and linkages in the following molecule:

PRACTICE: Which of the following elements likely make up the largest portion of the mass in an organism?

a) Phosphorus

b) Sodium

c) Magnesium

d) Fluorine



Ionic & Covalent Intramolecular Bonds

Noncovalent Intermolecular Forces

Do atoms share electrons?

Type of Electron Sharing

________ Covalent Bonds ________ Covalent Bonds Ionic Bonds

Electronegativity of Atoms

Label with the appropriate intermolecular force:

Complete the chart:

Appropriately label the chemical bonds:

Atoms differ greatly

None

Examples

CONCEPT: CHEMICAL BONDS

●Chemical bonds are how individual atoms interact and connect with each other.

□ ______-molecular bonds are within the molecule.

□ _____-molecular bonds exist between different molecules.

EXAMPLE:

●Ionic bonds: interactions between atoms that have opposite charges due to a loss/gain of electrons (e-).

●Covalent bonds: occur when two atoms ______ a pair of electrons equally or unequally.

□ Electrons in a _________ covalent bond are equally shared but

□ Electrons in a ______ covalent bond are unequally shared.

●________________ (an atom’s affinity for e-) determines if the covalent bond is polar or nonpolar.

EXAMPLE:

●Hydrogen bonding: interaction involving a hydrogen atom & electronegative atoms like N, O, or F.

●Dipole: a shift in ________ density due to electronegativity differences between atoms.

□ Dipole-dipole interactions exist between two dipoles.

●Van der Waals forces exist between all molecules (result from ___________ dipoles).

EXAMPLE:

_____________ _____

_____________ _____

_______ sharing of electrons _______ sharing of electrons

Atoms differ Atoms have same or similar



1) 2)

CONCEPT: CHEMICAL BONDS

PRACTICE: Which of the following is classified as a nonpolar molecule?

a)

b)

c)

d)

PRACTICE: Identify the types of chemical bonds present in scenarios #1 & 2 below:



Maleic Acid

(Cis configuration)

Fumaric Acid

(Trans configuration)

Maleic acid & fumaric acid are

stereoisomers to one another.

Ethane Conformations

Configurations & Conformations

Resonance

Label the configurations of the enantiomers below:

CONCEPT: ORGANIC CHEMISTRY

●Organic chemistry focuses on the structure, properties & reactions of ___________-containing compounds.

□ Carbon makes up about 62% of the dry weight of the human body, showing its importance to life.

●Stereochemistry refers to the spatial _____ arrangement of atoms/molecules.

●_________________: same atomic composition, different spatial 3D arrangement.

EXAMPLE:

●Stereochemistry considers both a molecule’s configuration & possible conformations.

□ Configuration: a ______ 3D arrangement (only changed by breaking/reforming bonds).

□ Conformations: potentially_________ 3D arrangements.

●__________ ______: a carbon in a molecule bounded to four distinct chemical groups.

□ A chiral center can have one of two possible configurations (___ or ___).

●______________________: same chiral molecules with opposite chiral configurations.

□ Enantiomers are nonsuperimposable mirror images that differ in chemical properties.

EXAMPLE:

●Resonance is the ________________ of electrons within a molecule and has an energy stabilizing effect.

●Separate resonance structures are not actual transient states of the molecule & a __________ is the best representation.

EXAMPLE:

Mirror

____-Thalidomide ____-Thalidomide

Chiral Configurations

Staggered

Conformation

Eclipsed

Conformation



A) B)

CONCEPT: ORGANIC CHEMISTRY

PRACTICE: Determine the configuration of the following alkenes:

PRACTICE: A) Identify the chirality centers in the molecule.

B) Determine the configuration of each chirality center.

Fischer Projections

●__________ Projections: a molecular drawing style used commonly to portray chiral compounds.

□ Horizontal bonds are all popping out of the page as __________.

□ Vertical bonds are all going into the page as __________.

EXAMPLE: Determine the R/S configuration of each chirality center in the Fischer projection below.

PRACTICE: Determine the R/S configuration of each chirality center in the Fischer projection below.

COOH

CH3

H H2N

COOH

CH3

H

H OH

HO



Open Systems

Gibbs Free Energy Equation

System & Surroundings

Understanding Entropy

Portion of energy that can-do work

Total energy of a system

Units of Kelvin

Measure of disorder/randomness

CONCEPT: ENTROPY

●Entropy: a measure of randomness & a property of _________________.

□ Laws of thermodynamics: describes flows & changes of heat, energy & matter in reactions.

EXAMPLE:

●__________: local portion of the universe that we are focusing on; (surroundings: rest of the universe).

●Biological systems: open systems that exchange both ________ & _________ with the surroundings.

EXAMPLE:

●Entropy: a measure of ____________, or randomness; the greater the disorder, the ___________ the entropy.

●Reactions move the Universe toward a state of maximum entropy.

□ Local entropy can decrease if accompanied by an _____________ in universal entropy.

□ High universal entropy is associated with more ____________ & lower ____________ within a system.

EXAMPLE:

●Gibbs Free Energy Equation expresses the link between changes in entropy (ΔS), enthalpy (ΔH) & free energy (ΔG).

EXAMPLE: Appropriately label each term:

Solar

Energy Chemical

Energy Mechanical

Energy Heat Heat Heat

Chemical Reaction Systems

Glucose Glucose-6-phosphate

Hexokinase

ATP

ADP

Mg2+

Mass Out

Mass In

System

Boundary

Energy In

Energy Out

________

Products

Reaction Coordinate

Fre

e E

nerg

y of

Sys

tem

Reactants

Stable

____ Universal Entropy

High Universal Entropy

Order

_______

_

High Entropy Low Entropy



CONCEPT: ENTROPY

PRACTICE: When solid ice water melts to liquid water, how does that affect its entropy?

a) Entropy decreases.

b) Entropy increases.

c) Entropy stays the same.

d) Impossible to tell. Needs more information.

PRACTICE: How does the entropy change with the following reaction?

a) Entropy decreases.

b) Entropy increases.

c) Entropy stays the same.

d) Impossible to tell. Needs more information.

PRACTICE: Consider a reaction at 100˚C with ΔG = 15 kJ and ΔH = 40 kJ. Calculate the system’s change in entropy.

a) 139.13 kJ/K

b) -13.3 kJ/K

c) 0.15 kJ/K

d) 0.07 kJ/K



CONCEPT: SECOND LAW OF THERMODYNAMICS

●2nd law: 100% efficient energy conversion is impossible since _________ energy is lost, increasing universal entropy.

□ All _________________ processes increase entropy & proceed toward equilibrium (minimum potential energy).

□ ________ (system) entropy can decrease as long as it is offset by an increase in _____________ entropy.

EXAMPLE: 2nd Law of Thermodynamics.

Exergonic & Endergonic Processes

●Spontaneous processes: exergonic (-ΔG) & occur without outside intervention.

□ Associated with _____________ (breaking down) processes & are thermodynamically ____________.

●Nonspontaneous processes: endergonic (+ΔG) & require outside intervention (an energy input).

□ Associated with _____________ (building up) processes & are thermodynamically ______________.

□ Anabolic processes decrease local entropy but are still accompanied by an increase in ____________ entropy.

EXAMPLE:

●Exergonic & endergonic processes are both associated with an _______________ in universal entropy.

Larger Energy

Available

Smaller Energy Transferred

Heat

Heat

Energy Conversion

_______ _______



CONCEPT: SECOND LAW OF THERMODYNAMICS

PRACTICE: Which of the following statements is false?

a) All endergonic reactions have a +ΔG.

b) All endergonic reactions are catabolic.

c) All exergonic reactions have a -ΔG.

d) All exergonic reactions are spontaneous.

e) All of the above are true.

PRACTICE: Which of the following statements is true?

a) Spontaneous reactions are fast reactions.

b) Endergonic reactions are spontaneous.

c) Endergonic reactions tend to decrease local entropy.

d) All exergonic reactions decrease universal entropy.

e) All of the above are false.



Equilibrium Constant (Keq)

CONCEPT: EQUILIBRIUM CONSTANT

●4 features characterize biochemical reactions: 1) Spontaneity, 2)___________ ________, 3) Directionality, 4) Velocity.

EXAMPLE:

Equilibrium

●A reaction at ________________ has the following characteristics:

□ No _____ change in concentrations of reactants or products (forward reaction rate = reverse reaction rate).

□ No change in free energy (____ = 0).

□ At equilibrium, a reaction system’s energy is at its ___________ (most stable).

□ The ________ of product concentration to reactant concentration is constant.

●All reactions proceed toward ______________ equilibrium.

EXAMPLE:

●Ratio of product concentrations over reactant concentrations at equilibrium is called the equilibrium __________ (Keq).

□ Keq changes with _____________(T), but in biological systems, if not given, we assume T is ~298K.

EXAMPLE: Equilibrium Constant Equation

●When there are multiple products/reactants, their concentrations are _______________ to get the Keq.

□ Coefficients (#’s in front of molecules) are included into Keq as _________________.

EXAMPLE: Keq with multiple products/reactants & coefficients.

Equilibrium

Sys

tem

Fre

e E

nerg

y (G

)

Component Concentrations

4A 1B

1A 4B

3A 2B

Pure A

Pure B



CONCEPT: EQUILIBRIUM CONSTANT

PRACTICE: Calculate the equilibrium constant for the reaction below:

a) 106.67

b) 43.12

c) 0.0094

d) 133.89

PRACTICE: What is the equilibrium constant expression for the following reaction?

a)

b)

c)

d)

PRACTICE: Calculate the Keq for the following reaction to determine which of the following statements is true.

Equilibrium Concentrations: O2 = 0.2 M F2 = 0.3 M OF2 = 0.5 M

a) Reactants are favored.

b) Products are favored.

c) Reactants & products are equally favored.

d) Not enough information provided to make conclusions.

Equilibrium Concentrations: 0.15M 0.25M 0.50M

𝑁2(𝑔) + 3𝐻2(𝑔) 2𝑁𝐻3(𝑔)

2[𝑁𝐻3]

3[𝑁2][𝐻2]

[𝑁2][𝐻2]3

[𝑁𝐻3]2

3[𝑁2][𝐻2]

2[𝑁𝐻3]

[𝑁𝐻3]2

[𝑁2][𝐻2]3

𝑂2(𝑔) + 2𝐹2(𝑔) 2𝑂𝐹2(𝑔)



Reaction Direction

Reaction Under Standard Conditions˚

Reaction Under Physiological Conditions

ΔG˚ =

ΔG =

CH3OH

CO

H2

CONCEPT: GIBBS FREE ENERGY

●Recall the Gibbs free energy equation:

●Gibbs free energy: energy available to do _______.

□ Work is done when concentrations in a system __________ (no work is done at equilibrium, ΔG = 0).

□ Concentrations within a system influence the direction of a reaction.

●Cellular reactions are almost never at _______________ due to several factors.

●When a reaction is not at equilibrium, the reaction quotient (Q) replaces the equilibrium constant:

□ ____ __________ Principle: when equilibrium is disturbed, the reaction direction proceeds to restore equilibrium.

EXAMPLE: Consider the reaction below & complete the chart:

●Standard conditions allow scientists to compare different reactions under the same conditions.

●Equilibrium constant can be used to calculate the change in free energy under ________ ___________ (ΔG˚).

□ ΔG is the actual change in free energy of a system under any condition.

EXAMPLE:

●Standard conditions occur in a test tube in a lab, but physiological conditions _______ within biological systems.

□ ΔG˚ can be used to determine the actual change in free energy of a system under any condition (ΔG).

EXAMPLE: Calculate ΔG˚ & ΔG for the given reaction:



CONCEPT: GIBBS FREE ENERGY

PRACTICE: Consider a reaction where Keq=1.6 but Q = 3.19. What direction will the reaction proceed?

a) Forward.

b) Reverse.

c) Forward & reverse reactions proceed equally.

d) Not enough information provided to make conclusions.

PRACTICE: At equilibrium, the reaction A ⇌ B + C has the following component concentrations: [A] = 3 mM, [B] = 4 mM,

and [C] = 10 mM. What is the standard free energy change for the reaction & is it endergonic or exergonic?

a) – 6418 J

b) 6418 J

c) 10,698 J

d) – 10,698 J

PRACTICE: ΔG˚=141.7 kJ for the following reaction. Calculate ΔG: T=10˚C, [SO3] = 25mM, [SO2] = 50mM, & [O2] = 75 mM.

2 SO3(g)

2 SO2(g) + O2(g)

a) – 6,437 J

b) 39,938 J

c) -155,127 J

d) 138,865 J



Solubility

Water vs. Methane

CONCEPT: PROPERTIES OF WATER

●Water (H2O): polar, bent molecule with two ________ covalent bonds & two _____-_______ of electrons.

□ Each H2O forms up to ____ hydrogen bonds with neighboring molecules.

●Abundance & strength of ___________ bonds in water accounts for many of its unique properties:

□ ____ boiling point □ ____ Heat Capacity □ ____ density of solid ice (crystal formation)

□ ____ melting point □ ____ Heat of Vaporization □ Strong surface tension (cohesion + adhesion)

EXAMPLE:

●Solubility: the property of a _________ to be dissolved by a solvent.

●H2O is the biological solvent that interacts with other polar substances & dissolves _________________.

□ Electrolytes: molecules that dissociate to form ions & form dipole-dipole interactions with H2O.

□ ____________ electrolytes have a shell/layer of H2O molecules surrounding them (hydration shell).

●Water has a high ____________ constant.

□ H2O is perfect for dissolving proteins, carbohydrates, & nucleic acids (but not _________).

EXAMPLE:

●Compare H2O to a molecule of similar molecular weight & size, methane (CH4):



CONCEPT: PROPERTIES OF WATER

PRACTICE: Water stuck to the glass window shield of a car is an example of what?

a) High Surface Tension

b) Adhesion

c) Cohesion

d) High Heat Capacity

PRACTICE: Rank the following compounds according to increasing water solubility:

i) CH3-CH2-CH2-CH3

ii) CH3-CH2-O-CH2-CH3

iii) CH3-CH2-OH

iv) CH3-OH

a) i < iii < iv < ii

b) i < ii < iv < iii

c) iii < iv < ii < i

d) i < ii < iii < iv

e) None of the above are correct.



Water Flow

Osmosis Direction

Results of Osmosis

Lower [solute]

Higher ________

Higher [solute]

________ [H2O]

CONCEPT: OSMOSIS

●Diffusion: substance movement from high concentrations to low concentrations of the same substance.

●Osmosis: diffusion of a solvent (usually ________) across a semi-permeable membrane.

□ Osmotic pressure: pressure required to prevent the flow of solvent.

●Osmosis direction depends on the __________ (or the relative concentration of solutes dissolved in the solutions).

□ _______________ solutions have the same solute concentration.

□ _______________ solutions have lower solute concentrations.

□ _______________ solutions have higher solute concentrations.

EXAMPLE: Label the tonicity of the outside solution.

●H2O will move from ______ to ______________ solutions if solutes cannot diffuse across the membrane.

□ Water moves toward the more concentrated solute solution to dilute it until it is _____________.

●Water still moves from higher concentrations of water to lower concentrations of water:

□ Hypotonic solutions: lower solute concentrations but ____________ H2O concentration.

□ Hypertonic solutions: higher solute concentration but ___________ H2O concentration.

EXAMPLE: Direction of Osmosis

●Hyp__tonic environments: cause cells to swell like a hipp__ & potentially lyse (rupture/burst).

□ Cells with ______ __________ do not lyse in hypotonic solutions (membrane expansion prevented).

□ Preferred by plant cells due to increased _________ ___________ (water pressure on cell membrane).

●Hyp____tonic environments: dehydrate cells like a hyper-kid gets dehydrated.

________________

Outside

Inside

________________

Outside

Inside

________________

Outside

Inside

Animal Cells

Hypotonic

Hypertonic

Isotonic

Environment:

Plant

Cells

Environment:

Hypertonic

Isotonic

Hypotonic

Hyper-kids get dehydrated.



CONCEPT: OSMOSIS

PRACTICE: A) What is the tonicity of the outside solution in comparison to the cell?

a) Hypotonic

b) Isotonic

c) Hypertonic

d) electrotonic

B) What direction will the water flow?

a) Inside → Outside

b) Outside → Inside

c) Water flows in both directions.

d) No flow of water.

PRACTICE: Plants become turgid when placed in this type of solution:

a) Hypotonic

b) Isotonic

c) Hypertonic

d) Megatonic

10%

solute

0.1%

Solut

e



Hydrophobic Effect Explained

Protein Folding & Membrane Formation

CONCEPT: HYDROPHOBIC EFFECT

●The hydrophobic effect: phenomenon of the exclusion of _____________ substances by water.

□ Hydrophobic (water “fearing”) molecules are insoluble & form a separate phase in water.

□ Critical for _______ folding & the formation of membranes.

● In water, hydrophobic/nonpolar substances ________ to have a strong net affinity for each other, but that is not the case.

EXAMPLE:

●Hydrated nonpolar substances: cage-like shell/layer of water molecules around them (hydration shell).

□ Hydration shell H2O cannot participate in normal __________ bonding.

□ H2O in the hydration shell move ________ & form fewer but stronger hydrogen bonds (less stable).

□ Hydration shell H2O have __________ options for orientations in 3D space (more order & less entropy).

●It is thermodynamically __________ for hydration shells to merge when nonpolar molecules clump & reduce surface area.

●Entropy is decreased with clumping, but its largely offset by ____________ entropy of the H2O molecules that break free.

EXAMPLE:

●Hydrophobic effect: important for protein folding & the formation of membranes.

EXAMPLE: Protein folding. Membrane formation.

Phospholipid

Bilayer

= Unfolded Protein

Water =

Nonpolar R-group

Folded Protein

1) Hydrated nonpolar substance with

more-ordered H2O molecules in the

__________ shell (lowered

entropy of system).

Water

3) Clumping of nonpolar molecules ____________:

□ surface area

□ # of molecules in the hydration shell

□ local entropy

2) 2nd nonpolar substance further

_________ the entropy of system.

4) H2O molecules that break free

from the shell offset local entropy

decrease with overall increased

entropy of the surroundings.

= Phospholipid



CONCEPT: HYDROPHOBIC EFFECT

PRACTICE: Which of the following best explains the hydrophobic effect?

a) Hydrophobic substances have a strong net affinity for each other.

b) Hydrophilic substances increase local entropy upon clumping.

c) Hydrophobic substances clump due to their strong intermolecular forces.

d) Hydrophobic substances increase universal entropy when they clump.

PRACTICE: Which of the following is false concerning H2O molecules in the hydration shell around nonpolar substances?

a) Cannot participate in normal hydrogen bonding.

b) Form stronger hydrogen bonds than free H2O

c) Less ordered & higher entropy than free H2O

d) Less options for orientations in 3D space than free H2O



HC2O4-(aq) + H2O(l) H3O+

(aq) + C2O42-

(aq)

CONCEPT: ACIDS AND BASES

Br∅nsted-Lowry Acids & Bases

●Br∅nsted-Lowry Acids: substances capable of __________ a proton (H+).

●Br∅nsted-Lowry Bases: substances capable of ___________ a proton (H+).

●Recall: Conjugate acids & conjugate bases differ from each other, respectively, by a gain or loss of one proton.

EXAMPLE:

Amphiprotic Molecules

●______________ molecules: can act as either a Br∅nsted-Lowry acid or a base depending on conditions.

□ ________ is an amphiprotic molecule.

EXAMPLE:

PRACTICE: Which is the conjugate base of methylamine (CH3NH2)?

a) CH3NH-

b) CH3NH3+

c) CH2NH2-

d) CH3NH2OH-

e) None of the above.

PRACTICE: Consider the reaction & determine which of the following is a conjugate acid-base pair?

a) HC2O4- and H2O

b) H2O and C2O42-

c) HC2O4- and H3O+

d) HC2O4- and C2O4

2-

_____

_____

_____



H2O H2O H3O+ OH-

Pure water has a low concentration of

H3O+ & in pure water, the [H3O+] = [OH-].

CONCEPT: AUTOIONIZATION OF WATER

1) Water Autoionization

●Water tends to slightly autoionize, or react with itself to form ions: __________ cations (H3O+) & _________ anions (OH-).

●The ionization reaction is reversible & takes place _________.

EXAMPLE:

●Free protons, hydrogen ions & H+ are all essentially synonyms.

●H3O+ is commonly simplified to H+, but free protons are ____________ in aqueous systems (they exist as H3O+).

EXAMPLE: Alternative depiction of water ionization.

2) Ion Constant of Water (Kw)

●Because H+ & OH- participate in many biochemical reactions, their _________________ are relevant.

□ The [H+] & [OH-] can be determined from the equilibrium constant:

● The ____ _______ of water (Kw) is a simple rearrangement of the equilibrium constant & the product of [H+][OH-].

EXAMPLE: Keq & Kw for autoionization of water.

●Kw can differ depending on ____________, but in biological systems, Kw is always assumed to be 1.0 x 10-14 M2.

□ Kw allows us to calculate either [H+] or [OH-] when given the concentration of one of the ions.

PRACTICE: Calculate [H+] in a solution given that [OH-] is 1.0 x 10-10 M.

a) 1.0 x 10-2 M b) 1.0 x 10-3 M c) 1.0 x 10-4 M d) 1.0 x 10-5 M

PRACTICE: Calculate [OH-] in a solution given that [H+] is 1.0 x 10-11.8 M.

a) 1.0 x 10-11.8 M b) 1.0 x 10-6.8 M c) 1.0 x 10-4.5 M d) 1.0 x 10-2.2 M

Acid Base



CONCEPT: AUTOIONIZATION OF WATER

3) Proton Hopping

●Proton hopping: ________ and _______ ions can diffuse much more rapidly than other ions in aqueous solutions.

□ Protons from a H3O+ or H2O can continuously “hop” to neighboring water molecules or OH- ions.

EXAMPLE: Proton hopping.

PRACTICE: Which of the following ions is likely to diffuse the most rapidly in biological systems?

a) Ca2+

b) OH-

c) Mg2+

d) Cl-

PRACTICE: The magnitude of Kw indicates that _________________.

a) water autoionizes very slowly.

b) water autoionizes very quickly.

c) water autoionizes to a small extent.

d) water ionizes to a large extent (completely).



Lemon juice

Pure H2O

Bleach

CONCEPT: pH

1) Calculating pH

●Many enzymes & biochemical processes are strongly affected by the ______________ of protons [H+].

●pH: logarithmic measurement of the ____ ion concentration in a solution.

□ pH indirectly measures [OH-].

□ pH is mathematically defined as the __________ logarithm of [H+].

EXAMPLE: Determine the pH of a solution with a [H+] of 0.04 M.

a) pH = 11.2 b) pH = 7.5 c) pH = 3.6 d) pH = 1.4

PRACTICE: Determine the pH of a solution with a [H+] of 2 x 10-5 M.

a) pH = 2.2 b) pH = 4.7 c) pH = 10.9 d) pH = 6.1

2) pH Scale

●The pH scale goes from _____ to _____.

□ ___________ solutions have a pH value of _____ & the [H+] = [OH-].

□ ___________ solutions have pH value of ______ than 7 (pH < 7) & the [H+] > [OH-].

□ ___________ solutions have pH value of ______ than 7 (pH > 7) & the [H+] < [OH-].

EXAMPLE: pH Scale.

●[H+] or [OH-] _________ than 1 lead to pH values outside the normal 1-14 scale (much harder to measure).

□ Biological solutions typically stay in the normal range of the pH scale.



CONCEPT: pH

EXAMPLE: Determine the pH of a solution with a [OH-] of 3 x 10-4 M. Is the solution basic, acidic or neutral?

a) pH = 12.9

b) pH = 10.5

c) pH = 5.7

d) pH = 7



CONCEPT: ACID DISSOCIATION CONSTANT

1) Acid Dissociation Constant (Ka)

●Acid dissociation constant (Ka): is the Keq for an acid’s dissociation & a ____________ measure of the strength of an acid.

□ Also known as the _________ constant since it expresses the tendency of an ion to dissociate from a molecule.

□ The greater the Ka, the __________ the acid.

●________________ Acids: contain multiple acidic H atoms that can dissociate to H+.

□ There is one Ka for each acidic H.

EXAMPLE: Calculate Ka of uric acid (C5H4N4O3) if [C5H4N4O3]eq = 4.07 x 10-3 M & [C5H3N4O3-]eq = 7.27 x 10-4 M.

a) Ka = 9.7 x 10-5 c) Ka = 6.4 x 10-10

b) Ka = 4.2 x 10-8 d) Ka = 1.3 x 10-4

PRACTICE: Calculate Ka of propionic acid (CH3CH2CO2H) if [CH3CH2CO2H]eq = 0.2 M & [CH3CH2CO2-]eq = 1.62 x 10-3 M.

a) Ka = 1.3 x 10-5 c) Ka = 3.9 x 10-12

b) Ka = 7.8 x 10-10 d) Ka = 5.1 x 10-4



CONCEPT: ACID DISSOCIATION CONSTANT

2) pKa

●Ka values are sometimes inconveniently large/small but can be expressed on a ____________ scale with pKa values.

□ The greater the pKa, the __________ the acid.

EXAMPLE:

PRACTICE: Which of the following is the strongest acid listed?

a) Lactic acid, Ka = 1.38 x 10-4 c) Acetic acid, Ka = 1.76 x 10-5

b) Formic acid, pKa = 3.75 d) Propionic acid, pKa = 4.87



CONCEPT: HENDERSON-HASSELBALCH EQUATION

1) The Henderson-Hasselbalch Equation

●Strong acids have small pKa & ____________ dissociate, but weak acids do _____ completely dissociate.

□ Calculating pH of strong acid solutions is easy since initial acid concentration equals final [H+] (ex. [HCl]i = [H+]f).

□ Most biological acids are _________ acids.

● The Henderson-Hasselbalch equation: expresses relationship between pH & ______.

□ Used to determine: 1) The final _____ of a weak acid solution after it reaches equilibrium.

2) The ratio of [conjugate base] to [conjugate acid] when given pH.

EXAMPLE: Determine the ratio of [conjugate base] to [conjugate acid] for Aspirin (pKa = 3.4) in the blood (pH = 7.4)?

a) 16,000

b) 10,000

c) 7.9

d) 4,200

PRACTICE: What is the pH of a mixture of 0.02 M sodium formate & 0.0025 M formic acid (pKa = 3.75)?

a) pH = 4.21

b) pH = 1.27

c) pH = 4.65

d) pH = 9.34

PRACTICE: What is the ratio of [CH3COO-] / [CH3COOH] in an acetate buffer at pH = 7? pKa = 4.76.

a) 122.43

b) 173.78

c) 39.84

d) 96.31



CONCEPT: HENDERSON-HASSELBALCH EQUATION

PRACTICE: Consider 100 mL of a 1M acid solution (pKa = 7.4) at pH = 8. Calculate final pH if 30 mL of 1M HCl is added.

a) pH = 7.4

b) pH = 7.9

c) pH = 7.1

d) pH = 8.2



CONCEPT: DETERMINING PREDOMINATE SPECIES

●Recall: Henderson-Hasselbalch reveals ratio of [conjugate base] to [conjugate acid].

□ Conjugate ________ and conjugate _________ are different forms/species of a molecule.

●________________ species: the most abundant form of a molecule that exists under specific conditions.

□ ______ of the solution & ______ of the acid dictates the predominate species.

pH vs. pKa

●Comparing solution pH to an acid’s pKa reveals relative [Conjugate _______] & [Conjugate _______].

□ Recall: Conjugate bases are _______________ (1 less H) & Conjugate acids are _______________ (1 more H).

EXAMPLE: Comparing pH & pKa to fill-in the blanks.

PRACTICE: Fill-in the blanks and indicate the predominate species at pH 8.3.

a) Acetic acid.

b) Acetate.

PRACTICE: Consider the following pKa value for pyruvic acid. Which of the following species predominates at pH = 7.4?

a) Conjugate base (CB).

b) Conjugate acid (CA).

c) Neither predominates ([CA] = [CB]).

d) Not enough info to tell.



Equivalence point

[Weak Acid] = [NaOH]

pH = pKa

Inflection point

Equivalence point: [HCl] = [NaOH]

2) Titration of Weak Acids

CONCEPT: TITRATION

1) Understanding Titrations

●Titration: lab technique that measures pH changes of acid/base solutions & determines _____ values & [weak acids].

□ Solution of _______ concentration (titrant) is gradually added to a solution of unknown concentration (analyte).

□ Titrant continuously added to analyte until _______________ is reached (indicated by color change).

●Titration: used to determine: 1) concentration of acid/base in a solution.

2) pKa of a weak acid.

●Titration curve: plot of titration data with ________ pH on the y-axis & amount of _______ added on the x-axis.

□ Equivalence point (or endpoint): When moles of analyte present ___________ moles of titrant added.

EXAMPLE: Titration of a Strong Acid with a Strong Base.

PRACTICE: Which of the following titration curves expresses the titration of a weak acid with a strong base?

●Inflection point (or midpoint): when ______ of the acid is neutralized the pH = pKa of a weak acid.

□ Recall: When pH = pKa, the [conjugate base] = [conjugate acid].

●Equivalence point does not always equal pH = 7 (it depends on [H+] when a molar equivalent of titrant is added).

EXAMPLE: Titration of a Weak Acid with a Strong Base.

0.2

0.6

1.0

1.2

1.4

1.6

d)

c)

b)

a)



If pH = 7.2: [ ] = [ ]

If pH = 2.2: [ ] = [ ]

If pH = 12.7: [ ] = [ ]

CONCEPT: TITRATION

PRACTICE: You have an analyte solution of 50 mL of 0.2 M acetic acid (pKa = 4.8). What volume of 0.05 M NaOH titrant

needs to be added to get the final pH = pKa?

a) 20 mL

b) 50 mL

c) 100 mL

d) 150 mL

3) Titration of Polyprotic Weak Acids

●Some acids are _____________ (multiple acidic hydrogens) & have a pKa value for each acidic hydrogen.

●The titration curves for polyprotic acids have __________ inflection & equivalence points (a set for each acidic H).

□ Each inflection point indicates a ______ value of a different acidic hydrogen.

●The Henderson-Hasselbalch equation is helpful to consider during a titration.

EXAMPLE:

PRACTICE: Use the titration curve above. What is the predominate species in the solution of phosphoric acid at pH = 5?

a) H3PO4

b) H2PO4-

c) HPO4-2

d) PO4-3

PRACTICE: Titration confirms an acetic acid solution to be 0.1 M. Calculate the pH. (acetic acid Ka = 1.76 x 10-5 M).

a) 2.1

b) 3.6

c) 2.9

d) 8.3

pKa = 12.7

pKa = 2.2

pKa = 7.2



Equivalence point

pKa = 4.8

*The Henderson-Hasselbalch equation can

be used to __________ buffer solutions.

CONCEPT: BUFFER SOLUTION

1) Buffers

●Buffer: substance that _________ changes in pH when small/moderate amounts of strong acid/base are added.

EXAMPLE:

PRACTICE: A) What volume of 0.1 M acetic acid (pKa = 4.8) is required to make 1 liter of 0.1 M buffer solution at pH = 5.8?

a) 193 mL

b) 91 mL

c) 909 mL

d) 807 mL

B) What volume of 0.1 M sodium acetate is required?

a) 193 mL

b) 91 mL

c) 909 mL

d) 807 mL

2) Effective Buffers

●Weak acids/bases & their _____________ together create effective buffers.

●The effective buffering _________ of a weak acid is centered around the inflection point & the pKa.

□ The effective buffer range is ±___ of the pKa.

EXAMPLE: Effective Buffer Range of Acetic Acid.

1) 2) 3) 4)



CONCEPT: BUFFER SOLUTION

PRACTICE: Which of the following compounds would make for the best buffer at pH 8?

a) Acetic acid, pKa = 4.8

b) Tricine, pKa = 8.15

c) Glycine, pKa = 9.9

d) Tris, pKa = 8.3

3) Biological Buffers

●Buffers are critical to life! Living systems use weak acids as buffers & a way to maintain ________________.

□ Some buffers maintain intracellular pH whereas others maintain _____________ pH.

●The ____________ buffer system (HPO4-2 / H2PO4

-) maintains intracellular pH.

●The _____________ buffer system maintains extracellular pH.

EXAMPLE:

PRACTICE: MOPS (pKa =7.2) is a weak acid & acts as a buffer. Calculate the ratio of its basic/acidic species at pH = 6.0.

a) 0.098

b) 1.24

c) 0.377

d) 0.063



CH. 1 - PRELUDE: BIOCHEMISTRY AND THE GENOMIC...

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