Biochem Test 2

Front 1

When an enzyme is saturated with substrates,

Back 1

it will display zero-order kinetics

Front 2

The reaction,

Back 2

will be nearly doubled

Front 3

The type of bonding labeled 'L' in these figure is:

Back 3

Electrostatic attraction

Front 4

The type of bonding labeled 'O' in these figures is

Back 4

Covalent bonding involving the R-groups

Front 5

Which one shows hydrogen bonding of R-groups?

Back 5

P

Front 6

Which one shows covalent bonding of R-groups?

Back 6

O

Front 7

Which one shows electrostatic attraction of R-groups?

Back 7

L

Front 8

The type of bonding labeled 'N' in these figure is:

Back 8

Hydrogen bonding of the peptide backbone

Front 9

If a protein with the sequence PQRKYPIG is treated with trypsin, which will the products be?

Back 9

PQR K YPIG

Front 10

(Graph) Predict the closes value of Km

Back 10

6.45 mM

Front 11

Compute for Vmax for this experiment.

Back 11

8.33 x 10^-2 mM sec^-1

Front 12

In the SDS-PAGE (sodium dodecylsulfate - polyacrylamide gel electrophoresis) method, separation takes place on the basis of

Back 12

the sieving action of the gel, because all particles have approximately the same charge/mass ration, but different masses

Front 13

For an enzymatically catalyzed reaction in which the measured values for Km and Vmax are, respectively, 15.1 mM and 0.143 mM min^-1, what is the value of the turnover number? The concentration of enzyme used in the reaction is 10 μM turnover number is:

Back 13

0.143 x 10^2 min^-1

Front 14

A mixture of asp, asn, and arg is placed in the bed where the pH is 7, and the current is turned on. From left to right, which best represents the final positions of the individual amino acids?

Back 14

asp asn arg

Front 15

If the amino acid Trp were placed in the bed where the pH is 11, and the current were turned on, it would migrate closet to which of the following positions?

Back 15

pH 6

Front 16

Methods for breaking proteins into smaller peptides include all of the following except:

Back 16

Edman degradtation

Front 17

in isoelectric focusing gel electrophoresis

Back 17

there is a pH gradient that parallels the electric field gradient

Front 18

In the induced-fit model of substrate binding to enzymes

Back 18

there is a conformational change in the enzyme when the substrate binds

Front 19

Catalase breaks down hydrogen peroxide about 10^6 times faster than the uncatalyzed reaction. If the latter required one year to achieve a certain degree of completion, how much time would be needed by the catalase-catalyzed reaction?

Back 19

31.5 sec

Front 20

Incorrect protein folding resulting in exposure of hydrophobic regions can result in

Back 20

aggregation

Front 21

The purity of an enzyme at various stages of purification is best measured by

Back 21

specific activity of the enzyme

Front 22

A sample of a peptide of unknown sequence was treated with trypsin; another sample of the same peptide was treated with chymotrypsin. The sequences (N-terminal to C-terminal) of the smaller peptides produced by trypsin digestion were as follows:

Back 22

(B)

Met-Val-Ser-Thr-Lys-Leu-Phe-Ans-Glu-Ser-Arg-Val-Ile-Trp-Thr-Leu-Met-Ile

Front 23

The location of prosthetic groups is shown in this level of structure:

Back 23

tertiary structure (c)

Front 24

In sickle-cell anemia hemoglobin

Back 24

groups of hemoglobin molecules aggregate with each other

Front 25

In the Bohr effect the binding of oxygen to hemoglobin

Back 25

is decreased by the presence of H+ and CO2

Front 26

Proteins that aid in the correct and timely folding of the proteins are called

Back 26

chaperones

Front 27

Cyanogen bromide (CNBr) cleaves proteins

Back 27

after methionine residues

Front 28

Which of the following best describes a motif?

Back 28

a repetitive super secondary structure

Front 29

what happens when a protein is denatured?

Back 29

its secondary structure is disrupted but its primary structure remains intact

Front 30

when the substrate concentration is low, an enzyme reaction

Back 30

will display first-order kinetics

Front 31

Vitamin C (ascorbic acid) prevents scurvy because

Back 31

it is used to hydroxylate pralines in the primary structure of collagen

Front 32

which of the following best describes the structure of collagen

Back 32

it is a triple helix

Front 33

The typical order for the major steps of enzyme isolation would be (from first to last)

Back 33

homogenization,

self fractionation,

column chromatography,

electrophoresis

Front 34

If a protein with the sequence FEWPRQVDMARINE is treated with chymotrypsin, what will the products be?

Back 34

F EW PRQVMARINE

Front 35

Which of the following amino acid residues would most likely be found in the interior of a globular protein?

Back 35

leucine

Front 36

Other things being equal, what is a potential disadvantage of an enzyme having a very high affinity substrate?

Back 36

tight enzyme-substrate binding will reduce the forward rate constant for the reaction

Front 37

As an animal ages, the amount of cross-linking of collagen in tissue

Back 37

tends to increase

Front 38

how is the turnover number of an enzyme related to Vmax?

Back 38

The turnover number is Vmax divided by the free plus substrate-bound enzyme concentrations

Front 39

The Km expression is equal to

Back 39

(k-1 + k2) / k1

Front 40

If the y-intercept of a Lineweaver-Burk plot = 1.91 (sec/millimole) and the slope = 75.3 L/sec, Km equals:

Back 40

39.4 millimolar (mM)

Front 41

Domains are

Back 41

independently folded regions of proteins

Front 42

Which of the following is most directly related to the speed of a reaction

Back 42

The ΔGº‡ of the reaction

Front 43

The binding of oxygen to hemoglobin differs form the oxygen-binding behavior of myoglobin because

Back 43

oxygen binding to hemoglobin is cooperative

Front 44

In gel filtration chromatography

Back 44

materials are separated based on their size, the larger ones eluting first

Front 45

For the peptide Cys-Ala-Gly-Arg-Gln-Met the overall net ionic charge on this peptide at pH = 7 would be:

Back 45

+1

Front 46

The affinity of fetal hemoglobin for oxygen

Back 46

is higher than that of maternal hemoglobin

Front 47

The following methods are useful for cell homogenization:

Back 47

Sanitation

Freezing and thawing

Detergents

Enzymes

All

Front 48

In a sample consisting of lysine, leucine, and glutamic acid, which will be eluted last form an anion exchange resin at pH 7?

Back 48

glutamic acid

Front 49

In affinity chromatography, a protein

Back 49

which binds to the ligand will remain on the column

Front 50

The typical order of differential centrifugation for organelles is (from slowest speed / lowest g to fastest speed / highest g):

Back 50

whole cells, nuclei, mitochondria & chloroplasts, microsomes, cytosol