amino acids

Question 1

The unique cyclic structure of which of the following amino acids plays a central role in the formation of alpha helices and beta sheets?

Answer 1

proline.

Proline plays a central role in the FORMATION of alpha helices and beta sheets. While proline’s unique structure may also disrupt both alpha helixes and beta sheets, it’s ability to make sharp turns facilitates the FORMATION of both structures, with proline commonly being found at the beginning of alpha helices or at the turns in beta sheets.

Question 2

Electrophoretic separation of leucine from a protein sample would be least effective at which of the following pH values?

Answer 2

7.4

At physiological pH, leucine exists as a zwitterion.

Question 3

DNA and RNA are made up of _____. Proteins are made up of _____.

Answer 3

nucleotides/nucleic acids.

amino acids

Question 4

what is epigenetics?

Answer 4

epigenetics is the study of heritable phenotype changes that do not involve alterations in the DNA sequence.

Question 5

physiological pH of histidine

Answer 5

side chain = 6.5 so exists in both protonated and deprotonated since it about the same as physiological pH of 7

Question 6

proline has a _____ amino group

Answer 6

secondary

Question 7

glycine does not have a ____

Answer 7

chiral carbon

Question 8

proline and glycine are known as _____

Answer 8

alpha helix breakers

Question 9

cysteine has a ____ group

Answer 9

thiol

Question 10

thiols in cysteine are in a ____ environment

Answer 10

reducing

Question 11

a disulfide bridge occurs between cysteines in the _____ environment

Answer 11

extracellular; oxidized environment

Question 12

antioxidants keep the intracellular space a _____ environment

Answer 12

reducing (so nothing becomes oxidized)

Question 13

cysteine turns into ____ when it is oxidized

Answer 13

cystine

Question 14

amino acids are chiral and can rotate light (optical activity) except the amino acid _____

Answer 14

glycine

Question 15

what is a zwitterion?

Answer 15

has both negative and positive charges

Question 16

name the alkyl amino acids

Answer 16

glycine, alanine, valine, methionine, leucine, isoleucine, proline

Question 17

aromatic amino acids

Answer 17

phenylalanine, tryptophan

Question 18

polar neutral amino acids

Answer 18

serine, threonine, asparagine, glutamine, cysteine, tyrosine

Question 19

acidic amino acids

Answer 19

aspartic acid and glutamic acid

Question 20

basic amino acids

Answer 20

arginine, lysine and histidine

Question 21

primary protein structure is the ____

Answer 21

peptide bonds

Question 22

secondary protein structure are the ____

Answer 22

H-bonds, alpha helix, and B-pleated sheets

Question 23

tertiary structure are the ____

Answer 23

V.d waals forces, disulfide bridges and hydrophobic interactions

Question 24

quaternary structure are the ____

Answer 24

subunit interactions

Question 25

increased temperature affects the _____ structures

Answer 25

2, 3 and 4 not the primary!

Question 26

pH disrupts the ____bonds

Answer 26

ionic, which affects the tertiary and quaternary structure

Question 27

chemicals affect the _____ structures

Answer 27

2, 3 and 4

Question 28

enzymes affect the ____

Answer 28

peptide bonds

Question 29

what are the 4 catalytic strategies that enzymes use to make reactions go faster?

Answer 29

1. acid/base 2. covalent 3. electrostatic 4. proximity/orientation

Question 30

what are coenzymes?

Answer 30

organic carrier molecules ex. NADH is an electron carrier

Question 31

cofactors _____ in catalysis

Answer 31

participate

Question 32

what is vitamin B3?

Answer 32

niacin which is a precursor for NAD

Question 33

minerals are ____

Answer 33

inorganic cofactors ex. magnesium

Question 34

amylase is found in the ____ and pepsin is found in the _____

Answer 34

mouth (functions at pH=7); stomach (functions at low pH)

Question 35

A ____ catalyzes the formation of a single bond between two substrates through the elimination of water.

Answer 35

ligase

Question 36

_______ catalyzes the first committed step of glycolysis

Answer 36

Phosphofructokinase 1

Question 37

_____ are inactive enzymes that require covalent modification to become active

Answer 37

zymogens

Question 38

covalent modifications for enzymes

Answer 38

1. small post translational 2. zymogens 3. suicide inhibitors

Question 39

deoxyribose is missing an ____

Answer 39

oxygen

Question 40

purines have ___ rings

Answer 40

2

Question 41

pyrimidines have ___ ring(s)

Answer 41

1

Question 42

what does telomerase do

Answer 42

lengthens telomeres

Question 43

you can only had nucleotides going from the ____ direction

Answer 43

5' to 3'

Question 44

helices breaks the ____

Answer 44

hydrogen bonds between nitrogenous bases