Chapter 5 Reading Quiz1. What does “hydrolysis” literally mean?

2. What element composes the backbone of the 4 macromolecules?

3. What subunits come together to make a protein?

4. List the 3 other macromolecules.

5. What is the main function of DNA?

Splitting water

Carbon!

Amino acids Carbohydrates

Lipids

Nucleic acids

information

1. List the four major classes of biomolecules.

1. Carbohydrates

2. Lipids

3. Proteins

4. Nucleic Acids

2. Explain how organic polymers contribute to biological unity and

diversity.

Unity – there are only 40 – 50 monomers used to make all macromolecules

Diversity – new properties emerge when these monomers are arranged in different ways…leading to the diversity of life

3. Describe how covalent linkages are formed (condensation) and broken (hydrolysis) in organic

polymers. Condensation

Polymerization reaction where monomers are covalently linked, removing a water molecule

Remove H2O molecule

HydrolysisReaction process that

breaks covalent bonds between monomers by adding water molecules

Add H2O molecule

4. Explain how carbohydrates are classified.

Carbohydrates are classified by the number of simple sugars

They are organic molecules made of sugars and their polymers

5. List four characteristics of sugar.

1. An –OH group is attached to each carbon except one, which is =O

2. The size of the carbon skeleton varies from 3-7 carbons

3. Spatial arrangement around asymmetric carbons may vary (ex: enantiomers)

4. In aqueous solutions, many simple sugars form rings. (chemical equilibrium favors ring structures)

6. Identify a glycosidic linkage and describe how it is formed.

Glycosidic linkage – the covalent bond formed by a condensation reaction between 2 sugar monomers

Sugar + Sugar Big Sugar (monosaccharides) (glycosidic (disaccharide)

linkage)

7. Describe the important biological functions of polysaccharides.

1. Energy storage – in the form of starch and glycogen

2. Structural support – in the form of cellulose and chitin

8. Distinguish between the glycosidic linkages found in starch and

cellulose.

StarchGlucose monomers

in α configuration• -OH group is

BELOW ring’s plane

α 1-4 linkage

CelluloseGlucose monomers

in β configuration• -OH group is

ABOVE ring’s plane

β 1-4 linkage

9. Explain what distinguishes lipids from other major classes of

macromolecules.

Lipids – • Are insoluble in water!• Due to nonpolar C-H bonds• Known as fats and oils

10. Describe the unique properties, building block molecules and

biological importance of the three important groups of lipids: fats,

phospholipids and steroids.

Fats – made with glycerol, a 3 carbon alcohol and a fatty acid (carboxylic with a hydrocarbon tail)

Used for:• Energy storage• Compact fuel reserves• Cushioning and insulating

10. Continued….

Phospholipids – made with a glycerol, 2 fatty acids, a phosphate group, and a small chemical group

Characteristics:• Tails are hydrophobic• Will cluster in water • Forms cell membrane bilayers

10. Continued….

Steroids – are lipids that have 4 fused carbon rings with various functional groups attached

Example:• Cholesterol

- precursor to sex hormones and bile acids- common in cell membranes-atheriosclerosis

11. Identify an ester linkage and describe how it is formed.

Ester linkage – • Bond formed between a hydroxyl group

(-OH) and a carboxyl group (-COOH)• Forms fat through condensation

reactions that link glycerol to a fatty acid

-OH + -COOH

12. Distinguish between saturated and

unsaturated fat, and list some unique emergent properties that are a consequence of these

structural differences.

Saturated Fats• No double bonds

between carbons in tail

• Has maximum number of hydrogens

• Solid at room temperature – most animal fats

C-C-C-C

Unsaturated Fats• One or more double

bonds in tail• Tail kinks at C=C so

molecules do not pack closely enough to solidify

• Liquid at room temperature – most plant fats

C=C-C=C

13. Distinguish proteins from the other major classes of

macromolecules and explain the biologically important functions of

this group.

Proteins – a macromolecule that consists of one or more polypeptide chains folded and coiled into specific conformations

• Made up of various 20 amino acids• Vary widely in structure and function• Abundant – about 50% of cellular dry

weight (weight of cell minus water bulk)

13. Continued…important functions

1. Structural support2. Storage of amino acids3. Transport (hemoglobin)4. Signaling (chemical messengers)5. Cellular response to chemical stimuli

(receptor proteins)6. Movement (contractile proteins)7. Defense against foreign substances &

disease-causing organisms (antibodies)8. Catalysis of biochemical reactions

(enzymes)

14. List and recognize four major components of an amino acid, and explain how amino acids may be

grouped according to the physical and chemical properties of the side

chains.Four components:1. Hydrogen atom2. Carboxyl group (-COOH)3. Amino group (-NH2)4. Variable ‘R’ group (specific to each amino

acid)- the properties of the side chain determine the uniqueness of each amino acid

15. Identify a peptide bond and explain how it is formed.

Peptide bond = the covalent bond formed by a condensation reaction that links the carboxyl (-COOH) group of one amino acid to the amino (-NH2) group of another.

16. Explain what determines protein conformation and why it is

important.

• It is the 3D shape of a protein• Enables a protein to recognize & bind

specifically to another molecule (ex: hormone receptor)

• It is the consequence of the specific linear sequence of amino acids in the polypeptide

• Produced when new chains coil & fold spontaneously (due to hydrophobic interactions)

• It is stabilized by chemical bonds & weak interactions between neighboring regions of the folded protein

17. Define primary structure and describe how it may be deduced in

the laboratory.• It is the unique sequence of amino acids in a

protein• Determined by genes – slight changes can

affect function (ex: sickle-cell)In a laboratory…1. Determine amino acid composition by

complete acid hydrolysis of peptide bonds – identify the aa’s and proportions

2. Determine the amino acid sequence by partial hydrolysis with enzymes and break specific peptide bonds – deductively reconstruct from fragments

• Now automated sequencing

18. Describe the two types of secondary protein structure, and explain the role of

hydrogen bonds in maintaining the structure.

• Coiling & folding of polypeptide backbone

• H bonds between peptide linkages in the protein’s backbone help stabilize

1. Alpha helix• Helical coil stabilized by H bond every

4th peptide bond • Found in fibrous protein –

collagen/elastin

18. Continued…Beta pleated sheet

2. Beta pleated sheet• Sheet of antiparallel

chains are folded into accordion pleats

• Held together by H bonds

• Dense core of globular proteins & some fibrous protein

19. Explain how weak interactions and disulfide bridges contribute to

tertiary protein structure.

Weak Interactions• Hydrogen bonding

between polar side chains

• Ionic bonds between charged side chains

• Hydrophobic interactions between nonpolar in interior

Covalent linkage• Disulfide bridges

between 2 cysteine monomers brought together by folding

• Reinforces conformation

20. Using collagen and hemoglobin as examples, describe quaternary

protein structure.

Collagen• Fibrous protein

with 3 helical polypeptides supercoiled into a triple helix

Hemoglobin• Four subunits

grouped together (2 α chains and 2 β chains)

21. Define denaturation and explain how proteins may be denatured.

• Is the process that alters a protein’s native conformation and biological activity

Causes:• Transfer to an organic solvent-hydrophobic

insides go out and vice versa• Chemical agents that disrupt hydrogen,

ionic, and disulfide bonds• Excessive heat – thermal agitation disrupts

the weak interactions

22. Describe the characteristics that distinguish nucleic acids from the

other major groups of macromolecules.

Nucleic acids –• Contain phosphorus• Store and transmit hereditary information• Are polymers of nucleotides• Determine protein structure, function, etc.Examples – • RNA (ribonucleic acid)• DNA (deoxyribonucleic acid)

23. Summarize the functions of nucleic acids.

• To store and transmit hereditary information- directions for replication- information to run all cell activity- make up the genes for protein synthesis (the ‘brain’ for making anything)

24. List the 3 major components of a nucleotide, and describe how these monomers are linked together to

form a nucleic acid.

1. Pentose (5 carbon sugar)- ribose, deoxyribose

2. Phosphate – attached to the 5th carbon of the sugar

3. Nitrogenous base – pyrimidines & purines• Covalent bonds called phosphodiester

linkages bond (between the phosphate of one sugar and the sugar of another)

25. Distinguish between a pyrimidine and a purine.

Pyrimidine- six-membered ring

made up of carbon and nitrogen atoms

Ex: cytosine (C) thymine (T) – DNA uracil (U) – RNA

Purine- five-membered ring

fused to a six-membered ring

Ex: Adenine (A) Guanine (G)

26. List the functions of nucleotides.

• Monomers for nucleic acids• Transfer chemical energy from one

molecule to another (ex: ATP )• Are electron acceptors in enzyme-

controlled redox reactions of the cell (ex: NAD+)

27. Briefly describe the three-dimensional structure of DNA.

• Consists of 2 nucleotide chains wound in a double helix

• Sugar-phosphate backbones on the outside

• 2 strands held together by hydrogen bonds between the paired nitrogenous bases

• Van der waals attraction between stacked bases

• 2 DNA strands are complementary and serve as templates for new strands

• Long – 1000’s or millions of base pairs