Biochemistry

Question 1

Amino acids are (L/D) and have (S/R) configuration. The only exception to the rule is BLANK

Answer 1

L, S, cysteine

Question 2

How many non-polar, non-aromatic amino acids are there? What are they?

Answer 2

7. Alanine, Valine, Leucine, Isoleucine, Methionine, Glycine, Proline

Question 3

How many/what are the aromatic side chain amino acids

Answer 3

3. Tryptophan, Phenylalanine (non polar), Tyrosine (polar)

Question 4

How many/what are the non-aromatic polar amino acids?

Answer 4

5. Threonine, Serine, Asparagine, Glutamine, Cysteine.

Question 5

Amino acids with longer alkyl side chains (like isoleucine, alanine, etc) are strongly (hydrophobic/hydrophilic)

Answer 5

Hydrophobic

Question 6

Charged amino acids are (hydrophobic/hydrophilic)

Answer 6

Hydrophilic

Question 7

Outside of charged amino acids or longer alkyl chains, the rest of the amino acids are ((hydrophobic/hydrophilic/somewhere in the middle)

Answer 7

Somewhere in the middle

Question 8

Hydrophobic amino acids are found in the (interior/exterior) of proteins

Answer 8

Interior

Question 9

Amino acids are BLANK species, meaning they can accept or donate a proton. How they react depends on BLANK

Answer 9

amphoteric, pH of environment

Question 10

Ionizable groups (lose/gain) protons under acidic conditions. Opposite is true under basic conditions (true/false)

Answer 10

gain, true

Question 11

if pH is less than pKa, then majority of species will be (protonated/deprotonated)

Answer 11

protonated

Question 12

At very acidic pH values, amino acids tend to be …? Why?

Answer 12

positively charged. pKa > pH for amine group, making NH3 protonated. Carboxyl is protonated bc pKa > pH for carboxyl, making it COOH and thus neutral.

Question 13

Zwitterions

Answer 13

Dipolar ions, two charges neutralize one another

Question 14

pI

Answer 14

Isoelectric point. pH at which molecule is electrically neutral

Question 15

Trypsin cleaves at carboxyl end of BLANK and BLANK

Answer 15

arginine and lysine

Question 16

Chymotrypsin cleaves at carboxyl end of BLANK, BLANK, and BLANK

Answer 16

tryptophan, phenylalanine, and tyrosine

Question 17

How do solutes denature proteins?

Answer 17

They interfere with forces that hold proteins together. They break disulfide bridges reducing cystine back o 2 cysteine residues

Question 18

Oxidoreductase

Answer 18

Enzyme. Catalyzes oxidation-reduction reactions (transfer of electrons between molecules). In rxn’s that use these, electron donor is reductant and electron acceptor is oxidant. Like dehydrogenase, reductase

Question 19

Transferase

Answer 19

Enzyme. Catalyze movement of functional group from one molecule to another. Like aminotransferase. These include kinases (catalyze transfer of phosphate group)

Question 20

Hydrolase

Answer 20

Enzyme. Catalyze breaking of a molecule into two molecules using addition of water. Like phosphatase

Question 21

Lyase

Answer 21

Enzyme. Catalyzes cleavage of single molecule into two products. Common for them to be referred to as synthases.

Question 22

Isomerase

Answer 22

Enzyme. Catalyze rearrangement of bonds within a molecule

Question 23

Ligase

Answer 23

Enzyme. Catalyze addition/synthesis reactions. Most likely to be encountered in nucleic acid synthesis

Question 24

Substrate

Answer 24

Molecule upon which enzyme acts

Question 25

Active site

Answer 25

Location within enzyme where substrate is held during chemical reaction

Question 26

Apoenzymes vs heloenzymes

Answer 26

Apo do not have their cofactors, helo do have their cofactors

Question 27

Cofactor vs coenzyme

Answer 27

Both help enzymes be effective. Different in that cofactors are generally inorganic molecules/metal ions, often ingested as dietary materials. Coenzymes are small organic groups, majority of which are derivatives/vitamins

Question 28

Michaelis Menton equation

Answer 28

Describes how rate of reaction (v) depends on concentration of substrate and enzyme. v = (vmax * [S])/Km + S

Question 29

Km

Answer 29

Michaelis constant. Substrate concentration at which half of enzyme active sites are full

Question 30

Kcat

Answer 30

of substrate molecules converted to product

Question 31

Catalytic Efficiency

Answer 31

Kcat/Km. Higher value means more efficient enzyme

Question 32

Feedback inhibition

Answer 32

regulatory mechanism whereby catalytic activity of enzyme is inhibited by presence of high levels of product later in same pathway

Question 33

Competitive Inhibition

Answer 33

Inhibitor is similar to substrate and binds at active site. Can be overcome by adding more substrate. Vmax is unchanged, Km increases

Question 34

Noncompetitive inhibition

Answer 34

Inhibitor binds with equal affinity to the enzyme and enzyme-substrate complex. Vmax is decreased, Km is unchanged