Ch 5 Microbial Metabolism

Question 1

define metabolism

Answer 1

sum of all chemical reactions in a living organism

Question 2

define catabolism

Answer 2

enzyme regulated breakdown of complex organic compounds into simpler ones, generally hydrolytic (use water to break bonds), and exergonic (release more energy than consumed)

Question 3

define anabolism

Answer 3

enzyme regulated energy-required reactions, building of complex molecules from simpler ones, endergonic (consume more energy than produced)

Question 4

____ reactions provide the building blocks and the energy for ____ reactions (anabolic or catabolic)

Answer 4

catabolic provides for anabolic

Question 5

what determines a cells metabolic pathways

Answer 5

its enzymes

Question 6

define a catalyst

Answer 6

substances that can speed up a chem reaction

Question 7

enzymes (biological catalysts) are specific or non-specific

Answer 7

specific; acts on a specific substance called a substrate (depends on 3-D shape)

Question 8

the region of an enzyme that interacts w its specific substrate

Answer 8

active site

Question 9

what happens when a subrate binds to its enzyme

Answer 9

enables collisions to be more effective and lowers activation energy

Question 10

the crucial function of enzymes

Answer 10

speed up biochem reactions avoiding need to increase temperature of a living system
(speed up boichem reactions at temp compatible with normal functioning cell)

Question 11

what is an enzymes turnover number

Answer 11

max number of substrate molecules an enzyme can convert per sec

Question 12

what makes up an enzyme

Answer 12

an apoenzyme (inactive, protien portion) + a cofactor (nonprotien, activor portion)

Question 13

if the cofactor of an enzyme is an organic molecule it is called

Answer 13

a coenzyme

Question 14

the whole, active, enzyme is called

Answer 14

a holoenzyme

Question 15

examples of coenzymes

Answer 15

NAD, NADP, FAD, CoA

Question 16

what kind of chem reaction does oxidoreductase catalyze

Answer 16

oxidation-reduction reactions (in which oxygen and hydrogen are gained;reduction, or lost;oxidized)

Question 17

what kind of chem reaction transferase catalyzes

Answer 17

transfer of functional groups (amino group, acetyl group, etc.)

Question 18

oxidoreductase enzymes that remove hydrogen from a substrate are called

Answer 18

dehydrogenases

Question 19

oxidoreductases that add O2 to a substrate are called

Answer 19

oxidases

Question 20

what type of chem reaction hydrolase catalyzes

Answer 20

hydrolysis (addition of water)

Question 21

type of chem reaction catalyzed by lyases

Answer 21

removal of atoms without hydrolysis

Question 22

type of chem reaction catalyzed by isomerase

Answer 22

rearrangement of atoms within a molecule

Question 23

type of chem reaction catalyzed by ligase

Answer 23

joining of 2 molecules

Question 24

steps involved in mechanism of enzymatic action

Answer 24

1) substrate contacts active site
2) enzyme-substrate complex forms
3) substrate mlcl transform (rearanged, broken down, or combined w another substrate)
4) released
5) enzyme free for more reactions

Question 25

4 factors that influence enzyme activity

explain the relationships

Answer 25

1) Temp- rate increases as temp increases, reduces drastically beyond optimal point (denatures)
2) pH- above or below optimum ph, rate declines. too high or low denatures
3) Substrate Concentration- when high, maximum rate us attained (when the active site is always occupied/ saturated) once reaches max, more substrate doesn’t increase further
4) Presence of Inhibitors

Question 26

effect of enzyme on a chem reaction

Answer 26

lowers activation energy, more molecules get converted bc more possess activation energy needed

Question 27

how certain poisons (like asenic or cyanide) prevent enzymes from functioning

Answer 27

act as inhibitors

Question 28

competative vs noncompetative inhibitors

Answer 28

competative- fill activation site, compete w normal substrate for the site; shape similar to substrate
noncompetative- undergo allosteric inhibition; inhibitor binds to allosteric site rather than active site. causes active site to change shape

Question 29

define feedback inhibition

Answer 29

allosteric inhibitor stops the cell from making more of a substance it needs
Ex: several steps in making end product, final product allosterically inhibits the activity of an enzyme earlier in pathway (usually first in pathway)

Question 30

define phosphorylation

Answer 30

when a phosphate group is added to a chemical compound (ADP to ATP)

Question 31

define substrate level phosphorylation

Answer 31

substrate w phosphate group (a phosphorylated comound) directly transfers P to ADP. (usually P has energy from earlier oxidation reaction)

Question 32

define oxidative phosphorylation

Answer 32

energy from transferring e- (oxidation) to an e- carrier (nad or fad)
used in electron transport chain (sequence of e- carriers) to make ATP

Question 33

where e- transport chain is in prokaryotes v eukaryotes

Answer 33

eukaryotes- in inner mitochonrial membrane

prokaryotes- in plasma membrane

Question 34

define photophosphorylation

Answer 34

in plant cells; chlorophyl gives up e-, goes into electron transport chain to make ATP (light energy converted to ATP and NADPH)

Question 35

define an oxidation-reduction (redox) reaction

Answer 35

each time one subs is oxidized (loses e-) another is simultaneously reduced (gains e-) (one loses an e-, another gains)