Chapter 3 - Nucleic Acids, Proteins, and Enzymes

Question 1

if you were given a diagram of a nucleotide what you expect to find as its components

Answer 1

phosphate, sugar, and a base

Question 2

how is DNA different than RNA

Answer 2

it contains deoxyribose

Question 3

the observations that DNA with a higher G + C content is more stable at high temperatures than DNA with a high A+ T content because of what?

Answer 3

because each G and C pair forms three hydrogen bonds between antiparallel strands, whereas each A and T pair forms just two

Question 4

replication is the synthesis of ____ and transcription is the synthesis of _____

Answer 4

an identical copy of DNA; an RNA template based on the DNA template

Question 5

Quaternary structure of proteins refers to ____?

Answer 5

the number and kind of protein subunits the protein has

Question 6

the binding of a substrate to an enzyme

Answer 6

may involve hydrogen bonds and van der waals interactions

Question 7

in a reaction catalyzed by an enzyme

Answer 7

the enzyme does not affect the equilibrium constant for the reaction

Question 8

a competitive inhibitor of an enzyme-catalyzed reaction

Answer 8

is usually similar to the substrate

Question 9

the rate of a reaction catalyzed by an enzyme that has a single polypeptide chain

Answer 9

may be increase or decreased by temperature

Question 10

enzymes

Answer 10

may be subject to feedback inhibition

Question 11

what are nucleic acids

Answer 11

palmers that store, transmit, and express hereditary information

Question 12

two things proteins are essential for

Answer 12

metabolism and structure

Question 13

pyrimidine

Answer 13

six membered single ring structure

Question 14

purine

Answer 14

fused double-ring structure

Question 15

DNA sugar groups

Answer 15

Adenine
Cytosine
Guanine
Thymine

Question 16

RNA sugar groups

Answer 16

Adenine
Cytosine
Guanine
Uracil

Question 17

what makes the DNA structure less flexible than that of RNA

Answer 17

lack of a hydroxyl group at the 2’ position of the deoxyribose sugar

Question 18

complementary base pairing

Answer 18

In DNA 
A-T
C-G
In RNA
A-U
C-G
held together primarily by hydrogen bonds

Question 19

RNA characteristics

Answer 19

single stranded
can fold back on itself to form a double stranded helix
this folding occurs by complementary base pairing

Question 20

DNA characteristics

Answer 20

double stranded
consists of two polynucleotide strands of the same length
strands are antiparallel: 5’ ends are at opposite ends of the double-stranded molecule
remarkably uniform
sugar-phosphate groups form the sides of the ladder and the bases with their hydrogen bonds form the rungs on the inside

Question 21

genome

Answer 21

complete set of DNA in a living organism

Question 22

Enzymes

Answer 22

catalytic molecules that speed up biochemical reactions. most enzymes are proteins (some are RNA molecules)

Question 23

Defensive proteins

Answer 23

such as antibodies recognize and respond to substances or particles that invade the organism from the environment

Question 24

peptide bonds

Answer 24

in the “backbone” of a protein are formed as covalent “peptide bonds” between adjacent amino acids.

Question 25

hormonal and regulatory proteins

Answer 25

such as insulin control physiological processes

Question 26

receptor proteins

Answer 26

receive and respond to molecular signals from inside and outside the organism

Question 27

storage proteins

Answer 27

store chemical building blocks-- amino acids -- for later use.

Question 28

Structural proteins

Answer 28

such as collagen provide physical stability and enable movement

Question 29

transport proteins

Answer 29

such as hemoglobin carry substances within the organism

Question 30

Genetic regulatory proteins

Answer 30

regulate when, how, and to what extent a gene is expressed

Question 31

functions of proteins

Answer 31

``` enzymes structure defense signaling receptor membrane transport storage bulk transport gene regulation ```

Question 32

what are the building blocks of proteins

Answer 32

amino acids

Question 33

how can amino acids be classified

Answer 33

on the amino acids they posses

Question 34

labels amino acids can receive

Answer 34

``` polar charged (hydrophilic) polar uncharged (hydrophilic) nonpolar (hydrophobic) ```

Question 35

what functional groups do amino acids contain?

Answer 35

nitrogen containing amin group and the (acidic) carboxyl group

Question 36

3 amino acids that are hydrophobic

Answer 36

glycine, proline, and cysteine

Question 37

primary structure of a protein

Answer 37

is established by covalent bonds

Question 38

____ of proteins are folded into 3D shapes

Answer 38

the polypeptide chains

Question 39

secondary structure of a protein

Answer 39

consists of regular, repeated, spatial patterns in different regions of a polypeptide chain. alpha helix beta pleated sheet

Question 40

tertiary structure of a protein

Answer 40

the polypeptide chain is bent at specific sites and then folded back and forth results in the polypeptides definitive three-dimensional shape

Question 41

secondary and tertiary structures derive from ___

Answer 41

primary structure

Question 42

quaternary structure of a protein

Answer 42

results from ways in which these subunits bind together and interact. Hemoglobin is an example of a protein with multiple subunits

Question 43

catalyst

Answer 43

used to speed up a reaction without itself being permanently altered proteins that are enzymes speed up biochemical reactions, acting as biological catalysts that are highly specific for their substrates

Question 44

substrate

Answer 44

name for reactants in a enzyme-catalyzed reaction

Question 45

an enzymes active site determines its ____

Answer 45

specificity

Question 46

active site

Answer 46

where the substrate molecule binds to the enzyme

Question 47

irreversible inhibition

Answer 47

if an inhibitor covalently binds to an amino acid side chain at the active site of an enzyme, the enzyme if permanently inactivated because it cannot interact with its substrate. EX: DIPF (diisoprpyl phosphorofluoridate)

Question 48

reversible inhibition

Answer 48

an inhibitor is similar enough to a particular enzyme's natural substrate that is can bind noncovalently to the active site, yet different enough that no chemical reaction occurs analogus to a key that inserts into a lock but does not turn it

Question 49

competitive inhibitor

Answer 49

when a molecule competes with the natural substrate for the active site

Question 50

noncompetitive inhibitor

Answer 50

binds to an enzyme at a site distance from the active site. this binding causes a change in the shape of the enzyme, altering its activity.

Question 51

allosteric regulation

Answer 51

occurs when a non-substrate molecule binds or modifies a site other than the active site of an enzyme

Question 52

the activity of allosteric enzyme complexes results from what

Answer 52

the activity of both positive and negative regulators

Question 53

what effects enzyme activity

Answer 53

temperature and ph

Question 54

feedback inhibition

Answer 54

when the end product is present at a high concentration, some of it binds to a site on the commitment step enzyme, thereby causing it to become inactive