BIOL 1406 Chapter 05

Question 1

four classes of large biological molecules

Answer 1

carbohydrates, lipids, proteins, and nucleic acids

Question 2

Macromolecules

Answer 2

are large molecules composed of thousands of covalently connected atoms

Question 3

polymer

Answer 3

is a long molecule consisting of many similar building blocks

Question 4

monomers

Answer 4

small building-block molecules

Question 5

condensation / dehydration reaction

Answer 5

occurs when two monomers bond together through the loss of a water molecule

Question 6

enzymes

Answer 6

macromolecules that speed up the dehydration process

Question 7

hydrolysis

Answer 7

Polymers are disassembled to monomers by hydrolysis, a reaction that is essentially the reverse of the dehydration reaction

Question 8

carbohydrates

Answer 8

include sugars and the polymers of sugars

The simplest carbohydrates are monosaccharides, or single sugars

Carbohydrate macromolecules are polysaccharides, polymers composed of many sugar building blocks

Question 9

monosaccharides

Answer 9

have molecular formulas that are usually multiples of CH2O

Glucose (C6H12O6) is the most common monosaccharide

Monosaccharides are classified by the location of the carbonyl group (as aldose or ketose); the number of carbons in the carbon skeleton

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

Question 10

disaccharide

Answer 10

is formed when a dehydration reaction joins two monosaccharides. This covalent bond is called a glycosidic linkage.

Question 11

polysaccharides

Answer 11

the polymers of sugars, have storage and structural roles. The structure and function of a polysaccharide are determined by its sugar monomers and the positions of glycosidic linkages.

Question 12

starch

Answer 12

a storage polysaccharide of plants, consists entirely of glucose monomers

Question 13

glycogen

Answer 13

is a storage polysaccharide in animals. Humans and other vertebrates store glycogen mainly in liver and muscle cells

Question 14

cellulose

Answer 14

a polysaccharide, is a major component of the tough wall of plant cells

is a polymer of glucose, but the glycosidic linkages differ

The difference is based on two ring forms for glucose: alpha and beta

Question 15

chitin

Answer 15

another structural polysaccharide, is found in the exoskeleton of arthropods.

Chitin also provides structural support for the cell walls of many fungi

Question 16

lipids

Answer 16

are the one class of large biological molecules that do not form polymers.

The unifying feature of lipids is having little or no affinity for water.

Lipids are hydrophobic becausethey consist mostly of hydrocarbons, which form nonpolar covalent bonds.

The most biologically important lipids are fats, phospholipids, and steroids.

Question 17

saturated fatty acids

Answer 17

have the maximum number of hydrogen atoms possible and no double bonds

Question 18

unsaturated fatty acids

Answer 18

have one or more double bonds

Question 19

hydrogenation

Answer 19

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

Question 20

phospholipid

Answer 20

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

Question 21

steroids

Answer 21

are lipids characterized by a carbon skeleton consisting of four fused rings

Question 22

cholesterol

Answer 22

an important steroid, is a component in animal cell membranes

Question 23

enzymatic proteins

Answer 23

function: selective acceleration of chemical reactions
example: digestive enzymes

Question 24

structural proteins

Answer 24

function: support
example: silk fibers, collagen and elastin in animal connective tissues; keratin in hair, horns, feathers

Question 25

storage proteins

Answer 25

function: storage of amino acids
example: ovalbumin in egg white; casein, the protein of milk; storage proteins in plant seeds

Question 26

transport proteins

Answer 26

function: transport of other substances
example: hemoglobin, transport proteins

Question 27

hormonal proteins

Answer 27

function: coordination of an organism’s activities
example: insulin, a hormone secreted by the pancreas

Question 28

receptor proteins

Answer 28

function: response of cell to chemical stimuli
example: receptors in nerve cell membranes

Question 29

contractile and motor proteins

Answer 29

function: movement
example: actin and myosin in muscles, protein in cilia and flagella

Question 30

defensive proteins

Answer 30

function: protection against disease
example: antibodies combat bacteria and viruses

Question 31

enzymes

Answer 31

are a type of protein that acts as a catalyst to speed up chemical reactions

Question 32

polypeptides

Answer 32

are polymers built from the same set of 20 amino acids

Question 33

protein

Answer 33

consists of one or more polypeptides

Question 34

amino acids

Answer 34

are organic molecules with carboxyl and amino groups.

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

linked by peptide bonds

Question 35

Four Levels of Protein Structure

Answer 35

The primary structure of a protein is its unique sequence of amino acids.
Secondary structure, found in most proteins, consists of coils and folds in the polypeptide chain.
Tertiary structure is determined by interactions among various side chains (R groups).
Quaternary structure results when a protein consists of multiple polypeptide chains.

Question 36

Primary Structure

Answer 36

the sequence of amino acids in a protein, is like the order of letters in a long word

Primary structure is determined by inherited genetic information

Question 37

Secondary Structure

Answer 37

The coils and folds of secondary structure result from hydrogen bonds between repeating constituents of the polypeptide backbone

Typical secondary structures are a coil called an  helix and a folded structure called a  pleated sheet

Question 38

Tertiary Structure

Answer 38

is determined by interactions between R groups, rather than interactions between backbone constituents

These interactions between R groups include hydrogen bonds, ionic bonds, hydrophobic interactions, and van der Waals interactions

Strong covalent bonds called disulfide bridges may reinforce the protein’s structure

Question 39

Quaternary Structure

Answer 39

results when two or more polypeptide chains form one macromolecule

Collagen is a fibrous protein consisting of three polypeptides coiled like a rope

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

Question 40

denaturation

Answer 40

loss of a protein’s native structure

Question 41

chaperonins

Answer 41

are protein molecules that assist the proper folding of other proteins

Question 42

x-ray crystallography

Answer 42

to determine a protein’s structure

Question 43

nuclear magnetic resonance (NMR) spectroscopy

Answer 43

which does not require protein crystallization

Question 44

bioinformatics

Answer 44

uses computer programs to predict protein structure from amino acid sequences