Ch. 2 continued…. - MS. RAGO'S CLASS WEBSITE - …INSECT EXOSKELETON; Fungi cell walls) SINGLE...

Ch. 2 continued….

Biological Molecules

4 Classes of

ORGANIC

MACROMOLECULES

Carbon: The Backbone of Life

• Living organisms consist mostly of carbon-based compounds (ORGANIC)

• Organic chemistry- study of compounds containing carbon, bonded to H and O (CHO)

© 2011 Pearson Education, Inc.

WHY Carbon???

• With 4 valence electrons, C forms 4 covalent bonds with a variety of atoms (wants 8!) ability makes large, complex molecules


= protons

-

= neutrons

-

= electrons-

-

_______________=

center of an atom.

Home to protons

and neutrons.

Carbon Atom

Positively charged

No charge

electrons travel in

regions outside the

nucleus called

orbitals

Nucleus

Figure 4.5

(a) Length

Ethane 1-Butene

(c) Double bond position

2-ButenePropane

(b) Branching (d) Presence of rings

Butane 2-Methylpropane

(isobutane)Cyclohexane Benzene

Hydrocarbons

• Hydrocarbons are organic molecules consisting of only carbon and hydrogen

• Lipid (fats)- have long hydrocarbon chains

• Hydrocarbon chains = many bonds = release a large amount of energy when broken apart


Figure 4.6

Nucleus

Fat droplets

(b) A fat molecule(a) Part of a human adipose cell

10 m

Chemical Functional Groups

• Functional groups – parts of organic molecules that are most commonly involved in chemical reactions

• The number and arrangement of functional groups = unique properties of molecule


Figure 4.UN02

Estradiol

Testosterone

• The 7 functional groups most important in the chemistry of life:

1. Hydroxyl group2. Carbonyl group3. Carboxyl group4. Amino group5. Sulfhydryl group6. Phosphate group7. Methyl group

*NEED TO MEMORIZE WHAT IT LOOKS LIKE, WHERE TO FIND IT (macromolecule), and HOW IT WILL INTERACT (particularly with H2O)


Figure 4.9-a

STRUCTURE

CHEMICALGROUP Hydroxyl

NAME OF

COMPOUND

EXAMPLE

Ethanol

Alcohols (Their specific names

usually end in -ol.)

(may be written HO—)

Carbonyl

Ketones if the carbonyl group is

within a carbon skeleton

Aldehydes if the carbonyl group

is at the end of the carbon skeleton

Carboxyl

Acetic acidAcetone

Propanal

Carboxylic acids, or organic acids

FUNCTIONAL

PROPERTIES• Is polar as a result of the

electrons spending more time

near the electronegative oxygen

atom.

• Can form hydrogen bonds with

water molecules, helping dissolve

organic compounds such as

sugars.

• A ketone and an aldehyde may be

structural isomers with different

properties, as is the case for

acetone and propanal.

• Ketone and aldehyde groups are

also found in sugars, giving rise

to two major groups of sugars:

ketoses (containing ketone

groups) and aldoses (containing

aldehyde groups).

• Found in cells in the ionized form

with a charge of 1 and called a

carboxylate ion.

Nonionized Ionized

• Acts as an acid; can donate an

H+ because the covalent bond

between oxygen and hydrogen

is so polar:

Figure 4.9-b

Amino Sulfhydryl Phosphate Methyl

Methylated compoundsOrganic phosphates

(may be

written HS—)

ThiolsAmines

Glycine Cysteine

• Acts as a base; can

pick up an H+ from the

surrounding solution

(water, in living

organisms):

Nonionized Ionized

• Found in cells in the

ionized form with a

charge of 1+.

• Two sulfhydryl groups can

react, forming a covalent

bond. This “cross-linking”

helps stabilize protein

structure.

• Cross-linking of cysteines

in hair proteins maintains

the curliness or straightness

of hair. Straight hair can be

“permanently” curled by

shaping it around curlers

and then breaking and

re-forming the cross-linking

bonds.

• Contributes negative charge to

the molecule of which it is a part

(2– when at the end of a molecule,

as above; 1– when located

internally in a chain of

phosphates).

• Molecules containing phosphate

groups have the potential to react

with water, releasing energy.

• Arrangement of methyl

groups in male and female

sex hormones affects their

shape and function.

• Addition of a methyl group

to DNA, or to molecules

bound to DNA, affects the

expression of genes.

Glycerol phosphate 5-Methyl cytidine

Figure 4. UN04

Adenosine

What is this structure??

What does it do for cells?

Figure 4. UN05

AdenosineAdenosine

Reactswith H2O

Inorganicphosphate

ATP ADP

Energy

Is this molecule soluble in water?

A.yesB.no

The general structure of amino acids are shown in this figure. What functional groups are highlighted in salmon and yellow, respectively?

a) Amino and carboxyl

b) Amino and carbonyl

c) Hydroxyl and carbonyl

d) Methyl and carboxyl

e) Methyl and hydroxyl

What functional group is commonly used in cells to transfer energy from one organic molecule to another?

a) carboxyl

b) sulfhydryl

c) hydroxyl

d) phosphate

e) amino

Review

• Identify the functional groups in this structure. What macromolecule is it?

ALL living things are made up of 4

classes of large biological molecules:

1. Carbohydrates

2. Lipids

3. Proteins

4. Nucleic acids


Macromolecules, polymers, monomers

• Polymer - long molecule consisting of many smaller building blocks

• Monomers- smaller building-block molecules of polymers

• Polymers:• Carbohydrates

• Proteins

• Nucleic acids

*Lipids – consider an exception; but usually built from smaller pieces


Analogy of macromolecules

The Synthesis & Breakdown of Polymers

• Condensation reaction (AKA dehydration synthesis)-

when two monomers bond together through the LOSS of a water molecule (DEHYDRATES!)

• Hydrolysis- breaks chemical bonds of polymers into monomers, USING water; essentially the reverse of the dehydration reaction (“Lyse”- break, loosen)



Animation: Polymers

Right-click slide / select “Play”

Figure 5.2(a) Dehydration reaction: synthesizing a polymer

Short polymer Unlinked monomer

Dehydration removesa water molecule,forming a new bond.

Longer polymer

(b) Hydrolysis: breaking down a polymer

Hydrolysis addsa water molecule,breaking a bond.

1

1

1

2 3

2 3 4

2 3 4

1 2 3

The Diversity of Polymers

• Macromolecules vary among cells of an organism, vary more within a species, and vary even more between species

• An immense variety of polymers can be built from a small set of monomers

• Macromolecules Tutorial/ Animations

HO


http://bcs.whfreeman.com/thelifewire/content/chp03/0302002.html

that consist of

Section 2-3

Carbohydrates Lipids Nucleic acids Proteins

Monosaccharides Fatty acids

& GlycerolNucleotides Amino Acids

Carbon

Compounds

include

which contain

that consist of that consist of that consist of

which contain which contain which contain

Carbon,hydrogen,

oxygen

Carbon,hydrogen,

Oxygen *

Carbon,hydrogen,oxygen, nitrogen,

phosphorus

Carbon,hydrogen,oxygen,

Nitrogen *

Go to

Section:

Concept Summary

* Phosphorus = phospholipid (2 tails) * Sulfur Types of Bonds: - Covalent (Alpha or beta

glycosidic)- Hydrogen (b/w

Types of Bonds: - Covalent and hydrogen- Ester linkages b/w hydrocarbon FA chain tails and glycerol head

Types of Bonds: - Covalent (b/w sugar/ phosphates and sugar/bases)- Hydrogen (b/w base pairs)

Types of Bonds: - PEPTIDE (b/w a.a.)

PRIMARY- Hydrogen (b/w R

groups of a.a) –SECONDARY

- disulfide bridges/ionic/ H bonds, hydrophobic interactions (b/w R groups of a.a) _TERT

Class: Elements made from:

Example: Functions: (SUBUNITS) Monomer and Basic Structural Diagrams

Carbohy-drate

C,H,O1:2:1

GLUCOSEC6H12O6

Mono-FructoseGlucoseGalactose

Di-LactoseSucrose

Poly-Starch GlycogenCellulose

1.Stores Short Term Energy

- Animals ONLY=

- Plants ONLY=

2. Structural

support within cells:-

-

MONOSACCHARIDE =

Mono + mono =

Mono + mono ++mono (X 100) =

Lipids Mostly

C, H

Verylittle

O

1. Stores LONG TERM Energy

2. Form cellmembranes

3. Waterproof coverings

4. Chemical messengers

5. Insulation6. Protection

1 glycerol3 fatty acids

Saturated-

Unsaturated-

GLYCOGEN

STARCH

PLANT CELL WALLS (CELLULOSE)

CHITIN (“KITE-IN”)

(INSECT EXOSKELETON; Fungi cell walls)

SINGLE SUGAR

POLYSACCHARIDE

FATSOILSWAXESSTEROIDSTestosteroneEstrogenCholesterol

NO DOUBLE BONDS IN FATTY ACID

(SINGLE bonds=Straight lines = solids)

@ LEAST 1 DOUBLE BOND (double = kink in the leg; can’t fit closely= liquids)

DISACCHARIDES

Saturated fat!

Nucleic acids

C HO P N

Stores and transmits hereditary information

Help in reproduction of cells

NUCLEOTIDES =

1.

2.

3.

ProteiNs CH O N*S

Shape of protein’s determine their functions:1. HELPS CONTROL

RATE OF REACTIONS (ENZYMES)

2. pump small molecules in and out of the cell

3. Aids in cell movement

4. Structural support-muscles (ACTIN/MYOSIN)5. Antibodies of immune system

AMINO ACIDS =

CLASS: Elements made of:

Examples: Functions: Monomer and Structural diagrams:

DNA/RNA

5-C SUGAR

PHOSPHATE

GROUP

NITROGENOUS

BASE

20 DIFFERENT

KINDS

HELD

TOGETHER BY

PEPTIDE BONDS!

*R GROUP- variable

that identifies each

of the 20 a.a.

Hemoglobin

Insulin

Collagen

Lactase

Trypsin

Pepsin

Carbohydrates (“-ose”)

• Serve as fuel and building material in cell walls

• Carbohydrates- include sugars and polymers of sugars

• Monosaccharides- single sugars; simplest carbohydrates

• Disaccharides – 2 monosaccharides held together by glycosidic bond

• Polysaccharides- macromolecules composed of hundreds of monosaccharide building blocks


Monosaccharides

• Usually have molecular formulas that are multiples of CH2O (1 C: 2 H: 1 O)

• Glucose (C6H12O6)- most common


Figure 5.3c

Aldose (Aldehyde Sugar) Ketose (Ketone Sugar)

Hexoses: 6-carbon sugars (C6H12O6)

Glucose Galactose Fructose

• FUNCTION: Monosaccharides serve as a major fuel for cells and as raw material for building molecules


Figure 5.4

(a) Linear and ring forms

(b) Abbreviated ring structure

1

2

3

4

5

6

6

5

4

32

1 1

23

4

5

6

1

23

4

5

6

Disaccharides

• Formed when a CONDENSATION reaction

• Joins 2 monosaccharides = covalent bond called a glycosidic linkage


Figure 5.5

(a) Dehydration reaction in the synthesis of maltose

(b) Dehydration reaction in the synthesis of sucrose

Alpha Glucose Alpha Glucose

Alpha Glucose

Maltose

Beta Fructose Sucrose

1–4glycosidic

linkage

1–2glycosidic

linkage

1 4

1 2


Animation: DisaccharideRight-click slide / select “Play”

Polysaccharides

• Polymers of sugars

• storage and structural roles

• Structure and function determined by sugar monomers AND the positions of glycosidiclinkages


Polysaccharides: Storage in PLANTS

• Starch- storage polysaccharide of PLANTS, consists entirely of glucose monomers

• store starch as granules within chloroplasts and other plastids or in roots (i.e. carrots, potatoes…)

• NEVER FOUND IN ANIMALS!

• Combination of AMYLOSE and AMYLOPECTIN• Amylose = Alpha glucose = Unbranching chain

(“STRAIGHT”) = Carbons #1, 4 bonding• Amylopectin = Alpha glucose = branching chain =

• 1, 4 AND Carbons #1, 6 bonding


Figure 5.6

(a) Starch:a plant polysaccharide

(b) Glycogen:an animal polysaccharide

Chloroplast Starch granules

Mitochondria Glycogen granules

Amylopectin

Amylose

Glycogen

1 m

0.5 m

Polysaccharides: Storage in ANIMALS

•Glycogen - storage polysaccharide in animals

• Stores mainly in liver and muscle cells

• Like Amylopectin = Alpha glucose = branchingchain= Carbons #1, 4 and 1, 6 bonding

• Difference = more branching chains


Figure 5.6

(a) Starch:a plant polysaccharide

(b) Glycogen:an animal polysaccharide

Chloroplast Starch granules

Mitochondria Glycogen granules

Amylopectin

Amylose

Glycogen

1 m

0.5 m

• Cellulose - major component of the tough cell wall in plant. (ie celery, corn)

• Like starch, cellulose is a polymer of glucose, but the glycosidic linkages differ!

• The difference is based on two ring forms for

glucose: alpha () and beta () 1, 4 bonds!


Polysaccharides: Structural in PLANTS

Figure 5.7

(a) and glucosering structures

(b) Starch: 1–4 linkage of glucose monomers (c) Cellulose: 1–4 linkage of glucose monomers

Glucose Glucose

4 1 4 1

4141

= OH BELOW the ring on C1; same side = OH ABOVE the O; alternation of sides

C1 = the carbon to the right of the O

• Chitin- major component of the tough exoskeletons of invertebrates (ie cockroaches, crabs) AND cell walls of many fungi

• Like cellulose (1, 4 BETA bonds); ALSO HAS NITROGEN!

Polysaccharides: Structural in ANIMALS * not in Cambridge book!

Figure 5.9

Chitin is used to make a strong and flexiblesurgical thread that decomposes after thewound or incision heals.


Polymers with glucose are helical• Starch (amylose/amylopectin)• Glycogen

Polymers with glucose are straight• Cellulose- parallel strands of long cellulose

molecules group into microfibrils (strongbuilding structure for plants)

• Chitin

Glycosidic Linkages and Shape

Cell wall

Microfibril

Cellulosemicrofibrils in aplant cell wall

Cellulosemolecules

Glucosemonomer

10 m

0.5 m

Figure 5.8

Starch and

Cellulose

Animation

http://www.sinauer.com/cooper5e/animation1401.html

http://www.uwfox.uwc.edu/users/joyperry/bot130/Chapter04/Animations_videos/4_4_2_struct_funct.swf

Hydrolysis of Cellulose• NOT EASY for animals to break bonds of

cellulose!

• Enzymes that digest starch by hydrolyzing linkages; can’t hydrolyze linkages in cellulose!

• Cellulose in human food passes through the digestive tract as insoluble fiber (ie celery, corn)

*Many herbivores, from cows to termites, have symbiotic relationships with these microbes to help break down the bonds in plant cell walls.


Which polysaccharide has the greatest number of branches?

a) cellulose

b) starch

c) amylose

d) glycogen

a) proteinsb) starchc) nucleic acidsd) fatty acids

If actively growing cells are fed 14C-labeled

glucose, what macromolecules will become

radioactive first?

Why are human enzymes that digest starch unable to digest cellulose?

a) Cellulose is made of amino-containing sugars that cannot be metabolized.

b) Cellulose is only in plants, therefore humans do not have enzymes to break plant polysaccharides.

c) Cellulose has beta-glycosidic linkages; starch-digesting enzymes break only alpha-glycosidic linkages.

d) Cellulose has alpha-glycosidic linkages that only bacterial enzymes can break.

Carbohydrate Lab Tests –POTENTIAL Practical Q!

1. Reducing/Non- Reducing Sugar test

2. Starch test

• Read p. 32-36 in sugar and starch lab tests Cambridge chapter

• Predict the results of the various test you will be doing of unknowns

(write in left margin of data table)

Carbohydrate Tests – Reducing and Non-Reducing Sugars

• Reducing sugar –Benedicts test (Most mono, disaccharides)

• Non-reducing sugar – no reaction to reducing; Acid/ base needed; neutral for Benedicts to work (SUCROSE)

Carbohydrate Tests – Presence of Starch test

• Potassium-Iodide (K2I) Solution= Strong + only for plant tissues (Storage carbohydrate in starchy plants- carrots, potatoes, etc)

LIPIDS

Lipids*Sometimes considered the class of macromolecules NOT formed of polymers

• Diverse group of hydrophobic molecules• having little or no affinity for water

• consist mostly of hydrocarbons

(formed of nonpolar covalent bonds)

• The most biologically important lipids:• Fats (Triglycerides)

• Phospholipids – cell membranes

• Steroids – hormones; cholesterol in cell membranes


Fats (TRIGLYCERIDES)

• Made from smaller molecules: • 1 glycerol head and 3 fatty acids tails

• A fatty acid consists of a carboxyl (-COOH) group attached to a long carbon skeleton


Figure 5.10

(a) One of three dehydration reactions in the synthesis of a fat

(b) Fat molecule (triacylglycerol)

Fatty acid(in this case, palmitic acid)

Glycerol

Ester linkage – cov. bond in fats holding glycerol head to tails

• Saturated fatty acids have the maximum number of hydrogen atoms possible and no double bonds

- SATURATED = SINGLE bonds= Straight lines of hydrocarbon chains = Solids at room temp (can pack together tightly)

• Lard, butter

• Unsaturated fatty acids have one or more double bonds

- Double bonds= kink in the hydrocarbon chains liquids at room temp (can’t pack together tightly)

-olive, vegetable, fish oils


SATURATED VS. UNSATURATED FATS


Animation: FatsRight-click slide / select “Play”

Figure 5.11

(a) Saturated fat(b) Unsaturated fat

Structuralformula of asaturated fatmolecule

Space-fillingmodel of stearicacid, a saturatedfatty acid

Structuralformula of anunsaturated fatmolecule

Space-filling modelof oleic acid, anunsaturated fattyacid

Cis double bondcauses bending.

A diet rich in saturated fats may contribute to cardiovascular disease through plaque deposits

Hydrogenation is the process of converting unsaturated fats to saturated fats by adding hydrogen

Functions of Lipids

• Long –term energy storage in adipose cells

• Structure of cell membranes

• Cushions vital organs

• Insulates the body

• Chemical messengers- Hormones


Phospholipids

• In a phospholipid, two fatty acids and a phosphate group are attached to glycerol

• The two fatty acid tails are hydrophobic, but the phosphate group and its attachments form a hydrophilic head


Figure 5.12

Choline

Phosphate

Glycerol

Fatty acids

Hydrophilichead

Hydrophobictails

(c) Phospholipid symbol(b) Space-filling model(a) Structural formula

Hyd

rop

hil

ic h

ea

dH

yd

rop

ho

bic

ta

ils

Figure 5.13

Hydrophilichead

Hydrophobictail

WATER

WATER

Fluid mosaic model

Phospholipids are the component of all cell membranes

http://www.susanahalpine.com/anim/Life/memb.htm

Steroids

• Steroids are lipids characterized by a carbon skeleton consisting of 4 fused carbon rings

• Sex hormones – estrogen and testosterone

• Cholesterol- important component in animal cell membranes; helps maintain structure and shape of cell


Figure 5.14

PROTEINS

Proteins• Proteins account for more than 50% of the dry mass

of most cells

• Many functions include : 1. Structural support (hair/fingernails, skeletal muscle)2. Storage (albumin in eggs, seeds,milk)3. Transport (channels in cell membranes, hemoglobin)4. Cellular communications (hormones- insulin,

enzymes)5. Movement (skeletal muscle, flagella, centrioles) 6. Defense against foreign substances (ie. Enzymes and

antibodies)


Figure 5.15-a

Enzymatic proteins Defensive proteins

Storage proteins Transport proteins

Enzyme Virus

Antibodies

Bacterium

Ovalbumin Amino acidsfor embryo

Transportprotein

Cell membrane

Function: Selective acceleration of chemical reactions

Example: Digestive enzymes catalyze the hydrolysis

of bonds in food molecules.

Function: Protection against disease

Example: Antibodies inactivate and help destroy

viruses and bacteria.

Function: Storage of amino acids Function: Transport of substances

Examples: Casein, the protein of milk, is the major

source of amino acids for baby mammals. Plants have

storage proteins in their seeds. Ovalbumin is the

protein of egg white, used as an amino acid source

for the developing embryo.

Examples: Hemoglobin, the iron-containing protein of

vertebrate blood, transports oxygen from the lungs to

other parts of the body. Other proteins transport

molecules across cell membranes.

Figure 5.15-b

Hormonal proteins

Function: Coordination of an organism’s activities

Example: Insulin, a hormone secreted by the

pancreas, causes other tissues to take up glucose,

thus regulating blood sugar concentration

Highblood sugar

Normalblood sugar

Insulinsecreted

Signalingmolecules

Receptorprotein

Muscle tissue

Actin Myosin

100 m 60 m

Collagen

Connectivetissue

Receptor proteins

Function: Response of cell to chemical stimuli

Example: Receptors built into the membrane of a

nerve cell detect signaling molecules released by

other nerve cells.

Contractile and motor proteins

Function: Movement

Examples: Motor proteins are responsible for the

undulations of cilia and flagella. Actin and myosin

proteins are responsible for the contraction of

muscles.

Structural proteins

Function: Support

Examples: Keratin is the protein of hair, horns,

feathers, and other skin appendages. Insects and

spiders use silk fibers to make their cocoons and webs,

respectively. Collagen and elastin proteins provide a

fibrous framework in animal connective tissues.


Animation: Structural ProteinsRight-click slide / select “Play”


Animation: Storage ProteinsRight-click slide / select “Play”


Animation: Transport ProteinsRight-click slide / select “Play”


Animation: Receptor ProteinsRight-click slide / select “Play”


Animation: Contractile ProteinsRight-click slide / select “Play”


Animation: Defensive ProteinsRight-click slide / select “Play”


Animation: Hormonal ProteinsRight-click slide / select “Play”


Animation: Sensory ProteinsRight-click slide / select “Play”


Animation: Gene Regulatory ProteinsRight-click slide / select “Play”

• Enzymes are a type of protein that acts as a catalystto speed up chemical reactions

• Enzymes function as workhorses that carry out the processes of life



Animation: EnzymesRight-click slide / select “Play”

Structure of Proteins

Monomers = Amino acids • organic molecules with carboxyl and amino

groups

• differ in their properties due to differing side chains, called R groups

• Amino acids are linked by peptide bonds

• Polypeptides are unbranched polymers built from the same set of 20 amino acids


Side chain (R group)

Aminogroup

Carboxylgroup

carbon

Figure 5.16

Nonpolar side chains; hydrophobic

Side chain(R group)

Glycine(Gly or G)

Alanine(Ala or A)

Valine(Val or V)

Leucine(Leu or L)

Isoleucine(Ile or I)

Methionine(Met or M)

Phenylalanine(Phe or F)

Tryptophan(Trp or W)

Proline(Pro or P)

Polar side chains; hydrophilic

Serine(Ser or S)

Threonine(Thr or T)

Cysteine(Cys or C)

Tyrosine(Tyr or Y)

Asparagine(Asn or N)

Glutamine(Gln or Q)

Electrically charged side chains; hydrophilic

Acidic (negatively charged)

Basic (positively charged)

Aspartic acid(Asp or D)

Glutamic acid(Glu or E)

Lysine(Lys or K)

Arginine(Arg or R)

Histidine(His or H)

20 Different Amino Acids separated by their R

groups; properties of each are indicative of R group

BASIC RULES TO KNOW: Charges or OH attached

= hydrophilic(+ bases, - acids)

• Rings, CH3 or H = nonpolar, hydrophobic

NONPOLAR and POLAR (water!) DON’T MIX well!!

Figure 5.17

Peptide bond

New peptidebond forming

Sidechains

Back-bone

Amino end(N-terminus)

Peptidebond

Carboxyl end(C-terminus)

Protein Shape and Function

• A functional protein consists of one or more polypeptides precisely twisted, folded, and coiled into a unique shape

• The sequence of amino acids determines a protein’s 3-D structure; structure determines its function


Figure 5.18

(a) A ribbon model (b) A space-filling model

Groove

Groove

Figure 5.19

Antibody protein Protein from flu virus

4 Levels of Protein Structure

1. Primary structure- the protein’s unique sequence of amino acids (met-leu-gly-…..)

2. Secondary structure- consists of coils and folds in the polypeptide chain (H-bonds to form alpha helix and beta pleated sheets)

3. Tertiary structure- interactions among various side chains (R groups- hydrogen, disulfide bonds, ionic bonds, etc.)

4. Quaternary structure- when a protein consists of multiple polypeptide chains (fibrous or globular structure)



Animation: Protein Structure IntroductionRight-click slide / select “Play”

Figure 5.20aPrimary structure

Aminoacids

Amino end

Carboxyl end

Primary structure of transthyretin


Animation: Primary Protein StructureRight-click slide / select “Play”

Figure 5.20b

Secondarystructure

Tertiarystructure

Quaternarystructure

Hydrogen bond

helix

pleated sheet

strand

Hydrogenbond

Transthyretinpolypeptide

Transthyretinprotein


Animation: Secondary Protein StructureRight-click slide / select “Play”

Secondary structure

Hydrogen bond

helix

pleated sheet

strand, shown as a flatarrow pointing towardthe carboxyl end

Hydrogen bond

Figure 5.20c


Animation: Tertiary Protein StructureRight-click slide / select “Play”

Figure 5.20f

Hydrogenbond

Disulfidebridge

Polypeptidebackbone

Ionic bond

Hydrophobic

interactions and

van der Waals

interactions

Figure 5.20g

Quaternary structure

Transthyretinprotein

(four identicalpolypeptides)

Figure 5.20h

Collagen

Hemoglobin

Heme

Iron

subunit

subunit

subunit

subunit

Figure 5.20i

Quaternary structure • Collagen is a fibrous protein consisting of three

polypeptides coiled like a rope

• Hemoglobin is a globular protein consisting of four polypeptides: 2 alpha and 2 beta chains

• Globular vs. fibrous proteins*CAMBRIDGE LIKES TO ASK ABOUT HOW YOU WOULD IDENTIFY EACH! (DIFFERENCES)



Animation: Quaternary Protein StructureRight-click slide / select “Play”

Sickle-Cell Disease: A Change in Primary Structure

• A slight change in primary structure can affect a protein’s structure and ability to function

• Sickle-cell disease, an inherited blood disorder, results from a single amino acid substitution in the protein hemoglobin


Figure 5.21

PrimaryStructure

Secondaryand TertiaryStructures

QuaternaryStructure

FunctionRed BloodCell Shape

subunit

subunit

Exposedhydrophobicregion

Molecules do notassociate with oneanother; each carriesoxygen.

Molecules crystallizeinto a fiber; capacityto carry oxygen isreduced.

Sickle-cellhemoglobin

Normalhemoglobin

10 m

10 m

Sic

kle

-cell h

em

og

lob

inN

orm

al

hem

og

lob

in

1

2

3

4

5

6

7

1

2

3

4

5

6

7

Denaturation of Proteins

• This loss of a protein’s native structure is called denaturation; becomes biologically inactive

• Alterations in • pH

• salt concentration

• temperature

• other environmental factors can cause a protein to unravel


Figure 5.22

Normal protein Denatured protein

tu

Nucleic Acids

Functions of Nucleic acids:

• store, transmit, and help express hereditaryinformation

• DNA and RNA• programmed unit of inheritance called a gene =

a.a. sequence for protein synthesis

Monomers = nucleotides


Figure 5.25-1

Synthesis ofmRNA

mRNA

DNA

NUCLEUS

CYTOPLASM

1

Figure 5.25-2

Synthesis ofmRNA

mRNA

DNA

NUCLEUS

CYTOPLASM

mRNA

Movement ofmRNA intocytoplasm

1

2

Figure 5.25-3

Synthesis ofmRNA

mRNA

DNA

NUCLEUS

CYTOPLASM

mRNA

Ribosome

AminoacidsPolypeptide

Movement ofmRNA intocytoplasm

Synthesisof protein

1

2

3

Figure 5.26

Sugar-phosphate backbone5 end

5C

3C

5C

3C

3 end

(a) Polynucleotide, or nucleic acid

(b) Nucleotide

Phosphategroup Sugar

(pentose)

Nucleoside

Nitrogenousbase

5C

3C

1C

Nitrogenous bases

Cytosine (C) Thymine (T, in DNA) Uracil (U, in RNA)

Adenine (A) Guanine (G)

Sugars

Deoxyribose (in DNA) Ribose (in RNA)

(c) Nucleoside components

Pyrimidines

Purines

EACH nucleotide= 1) a nitrogenous

base2) a pentose sugar, 3) one or more

phosphate groups

2 Group of nitrogenous bases:

1. Pyrimidines (cytosine, thymine, and uracil) have a single ring (SMALLER)

2. Purines (adenine and guanine) ring fused to a another ring (BIGGER!)

• In DNA, the sugar is deoxyribose; in RNA, the sugar is ribose


The Structures of DNA and RNA Molecules

• RNA molecules - single polypeptide chains

• DNA molecules - double helix

• One DNA molecule includes many genes


• The nitrogenous bases in DNA pair up and form hydrogen bonds: adenine (A) always with thymine (T), and guanine (G) always with cytosine (C)

• Called complementary base pairing

• Complementary pairing can also occur between two RNA molecules or between parts of the same molecule

• In RNA, thymine is replaced by uracil (U) so A and U pair


Figure 5.27

Sugar-phosphatebackbones

Hydrogen bonds

Base pair joinedby hydrogen bonding

Base pair joinedby hydrogen

bonding

(b) Transfer RNA(a) DNA

5 3

53

*Be able to COMPARE/CONTRAST

The structures of DNA and RNA!

REVIEW QUESTIONS!

Lipids

a) are made from glycerol and fatty acids.

b) contain nitrogen.

c) have low energy content.

d) are acidic when mixed with water.

e) do not dissolve well in water.

All lipids

Compared to tropical fish, arctic fish oils have

a) more unsaturated fatty acids.

b) more cholesterol.

c) fewer unsaturated fatty acids.

d) more trans-unsaturated fatty acids.

e) more hydrogenated fatty acids.

Lipids

Subunits and Metabolic Labeling

a) 35S-labeled sulfate

b) 32P-labeled phosphate

c) 14C-labeled leucine

d) 3H-labeled thymidine

e) 14C-labeled guanine

If you want to selectively label nucleic acids being

synthesized by cells, what radioactive compound

would you add to the medium?

Protein Structure and Amino Acids

a) on the exterior surface of the protein

b) in the interior of the protein, away from water

c) at the active site, binding oxygen

d) at the heme-binding site

Sickle-cell disease is caused by a mutation in the beta-

hemoglobin gene that changes a charged amino acid,

glutamic acid, to valine, a hydrophobic amino acid.

Where in the protein would you expect to find glutamic

acid?

Protein Structure

a) primaryb) tertiaryc) quarternaryd) all of the abovee) primary and tertiary

structures only

The sickle-cell hemoglobin

mutation alters what level(s)

of protein structure?

Macromolecular Structures and Bonds

a) Acidic pH denatures (unfolds and inactivates) proteins by disrupting their hydrogen bonds.

b) Citrus juice denatures proteins by disrupting their ionic bonds.

c) Citrus juice contains enzymes that hydrolyze peptide bonds to break apart proteins.

d) Citrus juice dissolves cell membranes by disrupting hydrophobic interactions.

Ceviche is prepared by marinating fresh raw fish in citrus juice for several hours, until the flesh becomes opaque and firm, as if cooked. How does citrus juice render the seafood safe to eat?

RNA and DNA

a) DNA encodes hereditary information; RNA does not.

b) DNA forms duplexes; RNA does not.

c) DNA contains thymine; RNA contains uracil.

d) all of the above

How does RNA differ from DNA?

Ch. 2 continued…. - MS. RAGO'S CLASS WEBSITE - …INSECT EXOSKELETON; Fungi cell walls) SINGLE...

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