Quiz 10/18/14

Question 1

Those mechanisms that depend directly on substrate-enzyme interactions are termed substrate-level regulation.

Answer 1

pH, inhibitors, temp

Question 2

is from a Greek word meaning “another shape (or state)”

Answer 2

allosteric

Question 3

enzymes regulated allostericly exist in ___ different shapes.

Answer 3

2

Question 4

in one form the enzyme has a ____ affinity for substrate….___ reaction rate

Answer 4

high, high

Question 5

in the other form the enzyme has ___ or ___ affinity for the substrate…. now rate.

Answer 5

little, no

Question 6

Which form the enzyme takes on is determined by the presence and binding of appropriate regulatory substances termed _______ ____

Answer 6

allosteric effectors.

Question 7

What size are allosteric effectors usually?

Answer 7

small

Question 8

What do allosteric effectors usually regulate

Answer 8

enzymes for which they are neither a substrate nor an immediate product.

Question 9

what causes a reversible alteration in the enzymes conformation

Answer 9

allosteric effector binding

Question 10

In addition to an active site many enzymes have an ______,

Answer 10

allosteric site

Question 11

where are the allosteric site located ______

Answer 11

allosteric domain

Question 12

______ is where effectors can bind and alter the shape of the enzyme.

Answer 12

allosteric domeains

Question 13

some allosteric effectors increase enzyme function when they bind.

Answer 13

allosteric activator

Question 14

Other effectors inhibit the enzyme’s function when they bind.

Answer 14

allosteric inhibitor

Question 15

What is the first step in the glycolytic pathway

Answer 15

phoshorylation of glucose-6-phosphate (G-6-P)

Question 16

Almost invariably, enzymes at first or early steps of a multi-step pathway are regulated _____

Answer 16

allosterically

Question 17

what reduces the rate of the first step effectively controls the whole pathway

Answer 17

feedback inhibition

Question 18

what includes anabolic and catabolic pathways

Answer 18

feedback inhibition

Question 19

feedback inhibitiors that do not resemble substrate

Answer 19

feedback inhibition

Question 20

Enzymes composed of multiple subunits do not exhibit typical M and M kinetics.

Answer 20

the property of cooperativity

Question 21

multimeric proteins often have multiple substrate binding sites

Answer 21

the property of cooperativity

Question 22

as each site on the enzyme becomes successively occupied, the affinity at remaining sites changes

Answer 22

the property of cooperativity

Question 23

in the property of cooperativity their are _______ sites on _____ subunits, the effect of substrate inding at one site is transmitted to other unfilled sites by enzyme conformational changes.

Answer 23

multiples, separate

Question 24

in the property of cooperativity an M and M plot, an allosteric enzyme exhibiting cooperative interactions shows a _____ curve instead of a usual ______ one

Answer 24

sigmoidal, hyperbolic

Question 25

binding at one site increases the affinity for substrate at other sites

Answer 25

positive cooperativity

Question 26

binding at one site reduces the affinity for the substrate at other sites

Answer 26

negative cooperativity

Question 27

positive cooperativiety binding at one site _____ the affinity for substrate at other sites

Answer 27

increases

Question 28

negative cooperativity binding at one site _____ the affinity for the substrate at other sites

Answer 28

reduces

Question 29

In this form of regulation, the activity of an enzyme is affected by the addition or removal of specific functional groups.

Answer 29

covalent modification

Question 30

what are some of the specific functional groups that can be added or removed using covalent modification

Answer 30

phosphate groups, methyl groups, acetyl groups

Question 31

Can covalent modification can be either _____ or ______. Either way, they act to raise or lower the activity of the enzyme.

Answer 31

reversible or irreversible

Question 32

________ is probably the best unerstood covalent modification.

Answer 32

phosphorylation/dephosphorylation

Question 33

reversible addition of phosphate groups are called

Answer 33

phosphorylation or dephosphorylation

Question 34

phosphorylation or dephosphorylation most often involves the transfer of the phosphate groups from ATP to the hydroxyl group of a _________ in the protein.

Answer 34

serine, threonine, or tyrosine

Question 35

Enzymes that catalyze the phosphorylation of other molecules

Answer 35

kinases aka phosphorylases

Question 36

enzymes that catalyze the process of removing a phosphate, i.e. catalyze dephosphorylation

Answer 36

phosphoprotein phosphotases

Question 37

The breakdown of glycogen in skeletal muscle cells is catalyzed by ___ ____.

Answer 37

Glycogen Phosphorylase

Question 38

how is glycogen phosphorylase kinased?

Answer 38

the conformational change from inactvie b form to active a form is accomplished when the inactive b form itself becomes phosphorylated by the addition of a phosphate group to a particular serine on each of the 2 subunits of the phosphoylase b molecule

Question 39

what is glycogen phosphorylase kinased?

Answer 39

phosphorylase kinase

Question 40

in addition to regulation by its phosphorylation state, glycogen phosphorylase is also ______ regulated

Answer 40

allostericly

Question 41

Glycogen Phosphorylase is inhibited by glucose and ____, but it is activated by ____

Answer 41

ATP, AMP

Question 42

Glycogen Phosphorylase is used in a muscle cell which already has an adequate glucose supply, active phosphorylase a can not function due to _______ allosterically inhibiting the enzyme.

Answer 42

glucose

Question 43

When a cell receives a hormonal signal it may trigger production of an allosteric effector, such as ______

Answer 43

cAMP (cylclic AMP)

Question 44

This messenger molecule cAMP functions as an ______ _____ of a many enzymes, including a cytosolic protein kinase

Answer 44

allosteric activator

Question 45

When phosphorylated, this cytosolic protein kinase catalyzes phosphorylation of many substrates, including _____

Answer 45

Phosphorylase Kinase.

Question 46

Active _____ ___ will phosphorylate the enzyme discussed above, _____ ____ _

Answer 46

phosphorylase kinase, glycogen phosphylase b

Question 47

one of the primary functions of sER was _____ ___

Answer 47

carbohydrate metabolism

Question 48

_____ liberated from glycogen into the cytoplasm of liver cells are quickly isomerized into G6P which is then dephosphorylated by an sER specific membrane bound enzyme.

Answer 48

Glucose monomers (GIP)

Question 49

In contrast, the enzyme _____ ___ which adds glucose units onto glycogen, responds in the opposite manner: inactive in the phosphorylated form and activated by dephosphorylation.

Answer 49

Glycogen Synthase

Question 50

In addition to regulation by phosphorylation Glycogen Phosphorylase is also an _____ ____

Answer 50

allosteric enzyme

Question 51

Glycogen Synthase is inhibited by _____ and ___, but it is activated by AMP.

Answer 51

glucose, ATP

Question 52

So many enzymes are regulated by ______ _____ mechanisms.

Answer 52

multiple regulatory

Question 53

multiple regulatory mechanisms allow the cell to respond ___ under a variety of _____ situations.

Answer 53

appropriately, different

Question 54

What allows the cell to fine tune its response to multiple signals

Answer 54

multiple regulatory mechanisms

Question 55

This type of activation involves the one-time, irreversible removal of a portion of the polypeptide chain by an appropriate proteolytic (protein-degrading) enzyme.

Answer 55

proteolytic cleavage

Question 56

Proteolytic Cleavage modification is especially well demonstrated in these proteases

Answer 56

pepsin, trypsin, chymotrypsin, carboxypeptidase

Question 57

Each of these is produced in an inactive form termed a ______ or _____. they must have a portion of their polypeptide removed to become active.

Answer 57

zymogen or proenzyme

Question 58

inactive zymogens have modified names...... pro-whatever or whatever-ogen

Answer 58

pepsinogen, trysinogen, chymotrypsinogen, procarboxypeptidase

Question 59

Why is it not prudent to synthesize these enzymes in their functional form?

Answer 59

inactive pepsinogen is secreted into the duodenum of the stomach in response to hormonal signals.

Question 60

The latter are proteolyticly activated initially by an ______ secreted by duodenal cells

Answer 60

enterokinase

Question 61

activated zymogens ____ almost all our ingested proteins into free amino acids, which are absorbed by the intestinal epithelium cells

Answer 61

digest

Question 62

_____ is synthesized in the pancrease as ______. When it reaches the small intestine it is activated by the removal of a hexapeptide from its N-terminus by an enterokinase or by cathepsin B, a lysosomal enzyme present in acinar cells.

Answer 62

Trypsin, trypsinogen

Question 63

What is an indicator of the First Molecular Event during experimental Pancreatitis

Answer 63

TAP (trypsin Activation Protein)