LECTURE 31

Question 1

enzymes are considered _____?

Answer 1

catalysts

Question 2

enzymes do this to spontaneous reactions?

Answer 2

accelerate

Question 3

what do enzymes do to the transitional state so that the reaction can occur?

Answer 3

lowering the energy state

Question 4

how do spontaneous reactions occur more rapidly?

Answer 4

increase substrate

decrease product energy

Question 5

how do enzymes accelerate the reactions?

Answer 5

by stabilizing the transitional state with van der waals, electrostatic and hydrogen bonds decreasing the activation energy

bring substrate molecules into close proximity with each other

Question 6

what is total activity in reference to enzyme activity?

Answer 6

specific activity x amt

Question 7

how is the specific activity of enzymes measured?

Answer 7

international units

Question 8

how does activity get changed for an enzyme?

Answer 8

change amount of enzyme present

change specific activity of existing enzyme molecules via feedback inhibition, regulatory proteins, enzyme phosphorylation, proteolytic activation

Question 9

what is a common example of regulatory proteins?

Answer 9

calmodulin

Question 10

name the two examples of enzyme phosphorylation?

Answer 10

kinases

phosphorylation

Question 11

what is the significance of K1? K2 and K3?

Answer 11

KI is a measure of the rate of formation of ES

causes ES to disappear

Question 12

what is the measure of affinity? what is this known as?

Answer 12

the rate of disappearance of ES (K2+K3) and divided by the rate of formation of ES (K1)

michaelis constant

Question 13

what does low Km mean?

Answer 13

low Km means high affinity

Question 14

high affinity means what kind of Km?

Answer 14

low Km

Question 15

low affinity means what kind of Km?

Answer 15

high km

Question 16

Km is the substrate concentration that produces what type of velocity?

Answer 16

half maximal velocity

Question 17

how is enzyme kinematics graphed?

Answer 17

double reciprocal or lineweaver burke plot

Question 18

how do high and low affinity enzymes look on a double reciprocal plot?

Answer 18

Vmax is the same for each, high affinity enzyme has a lower Km so -1/km will be a larger negative number

Question 19

this type of inhibitor competes for binding at the active site?

how is affinity and Km affected?

Answer 19

competitive inhibitor

affinity is decreased and km is increased

Question 20

this type of inhibitor binds at sites other than the active site, so they don’t change affinity for substrate, what happens to the rate of the reaction of Vmax?

Answer 20

decrease Vmax

Question 21

what is needed to help facilitate enzyme catalyzed reactions?

Answer 21

cofactors or coenzymes, i.e. vitamins

Question 22

what is the job of the cells?

Answer 22

sense
survive
respond
reproduce

Question 23

any response by a cell is a change in what?

Answer 23

total activity

total activity=specific activity x amount

Question 24

what does signaling mean for a cell? what are the examples?

Answer 24

information is being transferred from one place to another and that it brings about a response

direct electrical communication
chemical signals

Question 25

t/f, chemical signals are faster than electrical signals?

Answer 25

f, slower than electrical

Question 26

what are the three examples of chemical signals, name any subclasses?

Answer 26

neurotransmitters
hormones like polypeptides (insulin, somatotropin, IGF-1, FSH) and steroids (cortisol, estradiol, aldosterone)
local signals like paracrine (NGF, histamine, PGs, Kinins) and autocrine (adenosine)

Question 27

what is the response like for the polypeptides and steroids?

Answer 27

faster onset
short acting

slow onset
long acting

Question 28

these hormones alter the specific activity primarily, faster onset, shorter duration response

Answer 28

polypeptides (insulin, somatotropin, IGF-1, FSH)

Question 29

these hormones alter gene expressions primarily, so slower onset and longer duration response

Answer 29

steroids (cortisol, estradiol, aldosterone)

Question 30

these local signals are released by one cell and affect neighboring cells. Onset and duration varies

Answer 30

paracrine (NGF, histamine, PGs, Kinins)

Question 31

these local signals affect the behavior of the cell that released them; fast onset and duration varies

Answer 31

autocrine (adenosine)

Question 32

what type of hormone are the hydrophilic signals?

Answer 32

polypeptide hormones

Question 33

T/F, lipophilic signals are polypeptide hormones? how are these signals associated with total activity?

Answer 33

steroid hormones

total activity=specific activity (hydrophilic signals) x amount (lipophilic signals)

Question 34

what are examples of paracrine?

Answer 34

histamine

PGs
Thromboxanes
Leukotrienes
aka “eicosanoids”

Question 35

which of the eicosanoids are being constantly released? what are the eicosanoids made from?

Answer 35

PGs

arachidonic acid cleaved from membrane phospholipids by phospholipase A2 stimulated by:

epinephrine
bradykinin
thrombin
angiotensin II

Question 36

so we know eicosanoids come from arachidonate, what are the enzymes used to make them?

Answer 36

lipooxygenase to produce HPETE to produce LTs

cyclooxygenase to produce PGG then peroxidase to produce PGH, both activities fall under the same enyzme (PG synthase) then on to PGs and TBs (via thromboxane synthase)

Question 37

what is cyclooxgenase inhibited by?

Answer 37

aspirin, ibuprofen and indomethacin

Question 38

what do thromboxanes promote?

Answer 38

vasoconstriction and platelet aggregation

Question 39

what do prostaglandins promote?

Answer 39

platelet aggregation

Question 40

what do leukotrienes promote?

Answer 40

bronchoconstriction and vascular permeability

Question 41

what inactivates PGs responses?

Answer 41

15-hydroxyprostaglandin DHase (metabolizes eicosanoids) and cyclo oxygenase (destroys self)