1

The Chemical Building Blocks of Life

Biological Chemistry

2

Questions to ponder…..

1) What elements do all organisms include?

2) What are organic compounds?

3) Next to water, what is the most common substance in living things?

3

CARBON

• Carbon is unique because:

1. It has the ability to form stable & strong covalent bonds because of its structure

2. It can form chains of almost unlimited length bonding to other C atoms

3. It can form single, double & triple bonds….no other atom can do all this

4

Outline

• Biological or Organic Compounds • The Macromolecules (in a

nutshell) Proteins

Hormones, transport, structure & enzymes Nucleic Acids

Pass genetic info Lipids

E storage & barriers Carbohydrates

E source & structural support

Carbon atom

5

Biological Molecules

• The framework of biological molecules consists of carbon bonded to other carbon molecules, or other types of atoms.

– Hydrocarbons consist of carbon and hydrogen.

Covalent bonds store considerable energy.

6

Building Biological Molecules

• Functional groups– specific groups of atoms attached to

carbon backbones retain definite chemical properties Ex:??

7

The Macromolecules

• Include:– proteins– nucleic acids– lipids– carbohydrates

PLUS:Macromolecules are often polymers.

long molecule built by linking together small, similar subunits

8

Macromolecules

Dehydration synthesis removes OH and H during synthesis of a new molecule.

Hydrolysis breaks a covalent bond by adding OH and H.

9

Chemical reactions review…..

• Chemical reactions involve the making and breaking of chemical bonds.

• Chemical bonds “store” energy.

• When a bond is broken, energy is released (heat, light, sound)

10

Exergonic Reaction

• Exergonic Reaction is one in which more energy is released than used.

• Ex. Fireworks, cellular respiration, digestion

• These reactions involve the breaking of polymers into monomers

11

• Endergonic Reaction is one in which more energy

is absorbed (stored in bonds) than is released. • These reactions involve joining monomers into

polymers.• Ex. Photosynthesis, making proteins, etc.

12

Proteins

• Protein functions:– structure– movement– storage– defense– transport– regulation– enzymes

13

Structure is related to function!

• Structurally sophisticated.

• Shape determines function and is crucial to the job of a protein.

14

Monomer: Amino Acids (AA)

• twenty common AA (grouped into • 5 groups) compose all the proteins

AA are made in the ribosomes of

the cell & joined by peptide bonds

15

Amino Acids• Peptide bond links two amino acids.

– A protein is composed of one or more long chains of amino acids linked by peptide bonds (These are called polypeptides).

16

Protein Structure• Protein function is

determined by its shape.– Protein structure

primary - specific amino acid sequence

secondary - folding of amino acid chains

motifs - folds or creases

supersecondary structure

17

Protein Structure

tertiary - final folded shape of globular protein

domains - functional units

quaternary - forms when two or more polypeptide chains associate to form a functional protein

18

Enzymes

• Enzymes are proteins that function as a catalyst - they control the rate of a reaction without being consumed by the reaction.

• They usually speed up the rate of a reaction by lowering the amount of activation energy needed to start the reaction.

• End with -ase.• Ex. lactase•

19

Reaction with enzyme

20

How enzymes work…Induced Fit Model• The substrate (what the enzyme is going to work

upon) comes into contact with the active site of the enzyme.

• The enzyme “wraps” around the substrate breaking or forming bonds.

• The product is released.

21

Enzyme at work

22

Unfolding Proteins

• Denaturation refers to the process of changing a protein’s shape.

– usually rendered

biologically inactive salt-curing and pickling used to preserve

food temperature - high temperatures break

bonds pH- designed to work at a specific pH

23

Nucleic Acids: Main Functions

• Deoxyribonucleic Acid (DNA)– Encodes information used to assemble

proteins.• Ribonucleic Acid (RNA)

– Reads DNA-encoded information to direct protein synthesis.

24

Nucleic Acid Structure• Nucleic acids are composed of long

polymers of repeating subunits nucleotides - the monomer.

– five-carbon sugar– phosphate– nitrogenous base

adenine, cytosine,

guanine & either

thymine or uracil

25

Nucleic Acid Structure

• DNA :1. Sugar=deoxyribose2. Bases=ATCG3. Phosphate

RNA :• Sugar=ribose• Bases=AUCG• Phosphate

26

Structure of DNA

27

Lipids• Lipids made up of C & H with nonpolar bonds.

Lipids are not attracted to water-hydrophobic.

Ex: Fats, oils, waxes, and

steroids.• Phospholipids form the core of

all cell membranes.

Ex of a monomer of lipid like in

fats & phospholipids:

28

Lipids

• Steroids – include cholesterol (common in animal cell membranes) & hormones

• Anabolic steroids - synthetic variants of testosterone

• Testosterone causes buildup of bone and muscle mass in puberty.

• Too much testosterone can cause serious physical and mental problems: mood swings, depression, liver damage, increased blood cholesterol, infertility, testicular atrophy, breasts development

29

Fats:

• SATURATED FATS:

1. animal fats

2. commonly found in meats & dairy products

3. tend to be solid at room temperature

• POLYUNSATURATED FATS:

1. plant fats

2. cooking oils like sesame, peanut & corn oil

3. tend to be liquid at room temperature

30

Saturated vs. unsaturated fatty acids

31

Fats as Energy Storage Molecules• Fats, on average, yield about 9 kcal per

gram versus 4 kcal per gram for carbohydrates

• Animal fats are saturated while most plant fats are unsaturated

• Consumption of excess carbohydrates leads to conversion into starch, glycogen, or fats for future use.

32

Isomers isomers - alternative forms of the same

substance ex. 8 isomers of “glucose”

33

Carbohydrates• Carbohydrates :molecules that contain

carbon, hydrogen, and oxygen in a 1:2:1 ratio or sugars

– monosaccharides - simple sugars (the mononomers)

– disaccharides - two monosaccharides joined by a covalent

– bond– polysaccharides -

made of many monosaccharide subunits

34

Carbohydrate Transport

a) Humans transport glucose as a simple monosaccharide

b) plants transform glucose into a dissaccharide transport form

35

Storage polysaccharides….• Starch - plant storage

from glucose• Glycogen - animal

storage-stored in liver & muscle

36

37

38

Structural Carbohydrates• Cellulose - plants

– Building material of cell walls-

provides protection/support – animals can not digest cellulose - “fiber”– chitin - exoskeleton of

arthropods and in fungi cell walls

– modified form of cellulose

39

Summary

• The Biological Molecules.

Why are each important? Proteins

Nucleic Acid

Lipids

Carbohydrates

40

Summary

41