Midterm 1 pt. 3

Question 1

What is metabolism?

Answer 1

The totality of an organism’s chemical reactions, consisting of catabolic and anabolic pathways

Question 2

Catabolism vs. Anabolism?

Answer 2

Catabolism: release energy by breaking down complex molecules to simpler molecules.
Anabolism: consume energy to synthesize complex molecules from simpler molecules.

Question 3

1st and second law of thermodynamics?

Answer 3

1st law of thermodynamics: the energy of the universe is constant. Energy can be transferred and transformed, but it cannot be created or destroyed
2nd law of thermodynamics: Every energy transfer or transformation increases the entropy (disorder) of the universe

Question 4

How much energy is lost up trophic levels?

Answer 4

90%

Question 5

Spontaneous vs non-spontaneous reactions?

Answer 5

Spontaneous reactions are exergonic: they release energy (∆G <0)
Non-spontaneous reactions are endergonic: they require energy (∆G >0)

Question 6

Living cells are what kind of system?

Answer 6

Open, receive energy from outside and put out old energy

Question 7

What is ATP?

Answer 7

Adenosine triphosphate
1 adenosine (nitrogenous base) + 1 ribose (sugar) + 3 phosphate groups
The bonds “store” potential energy that can be released and used by many other reactions.

Question 8

Examples of chemical, transport, and mechanical work?

Answer 8

chemical: glutamine w/ ATP hydrolysis
mechanical: muscle contraction
transport: Na/ K pump

Question 9

How is ATP regenerated?

Answer 9

energy liberated from exergonic reactions during catabolism can be used to regenerate ATP through the phosphorylation of ADP
The phosphorylation of ADP into ATP is endergonic

Question 10

what is an enzyme?

Answer 10

enzyme: organic version of catalyst: it increases the rate of a very specific reaction without being consumed by the reaction.

Question 11

Example on non-protein enzyme?

Answer 11

ribosome

Question 12

Cofactor vs coenzyme?

Answer 12

Cofactor: inorganic molecule that helps the enzyme’s catalytic function (e.g. zinc, iron, copper, magnesium…)
Coenzyme: organic molecule that helps the enzyme’s catalytic function (e.g. ATP, NADH, most vitamins…)

Question 13

Competitive vs non-competitive inhibitors?

Answer 13

Competitive: same as substrate, blocks substrate from binding
Non-competitive inhibitors: enzyme binds at alternative site, changes shape to decrease effeicncy

Question 14

How does penicillin inhibit enzymes?

Answer 14

blocks binding site between layers of peptidoglycan cell wall, stops bacteria growth

Question 15

What is an allosteric reaction?

Answer 15

Molecules that regulate the enzyme activity by binding to another site on the protein can in fact either inhibit or stimulate the catalytic reaction: allosteric regulation.

Question 16

Allosteric activator v. inhibitor?

Answer 16

Activator: binds in active state, keeps active, stablilizes
inhibitor: binds in inactive state, keeps inactive, stabilizies

Question 17

Allosteric cooperativity?

Answer 17

when activator/ inhib joins, it becomes more stable (no osscilliating), and more are likely to join

Question 18

Feedback inhibition?

Answer 18

a metabolic pathway is halted by the inhibitory binding of its end product to an enzyme (tryptophan cycle, neg feedback)

Question 19

What is aerobic respiration?

Answer 19

is essentially the oxidation of glucose into CO2 and the reduction of O2 into H2O.

Question 20

What is anaerobic respiration?

Answer 20

uses SO4, sometimes NO3 or CO2 instead of O2 as final electron acceptor

Question 21

What is cellular respiration?

Answer 21

Cellular respiration: catabolic pathways of aerobic and anaerobic respiration, which break down organic molecules and use an electron transport chain for the production of ATP.

Question 22

3 kinds of cellular respiration?

Answer 22

glycolysis, oxidation of pyruvate, citric acid cycle, oxidative phosphorylation

Question 23

Facts of cellular respiration?

Answer 23

Uses NAD/ NADH as electron carrier, has high redox potential

Question 24

Chemiosmosis?

Answer 24

mechanism that uses potential energy in H gradient to drive systhesis of ATP

Question 25

The efficiency of cellular respiration?

Answer 25

34%

Question 26

strict/ obligate anaerobe, faculative anaerobe?

Answer 26

strict: no O2, anaerobic or fermentation
facultative: can switch from anaerobic to fermentation

Question 27

Where does photosynthesis occur?

Answer 27

thylakoid membrane in which proteins and pigments
are organized in photosystems.

Question 28

Photosystem?

Answer 28

light-capturing unit located in the thylakoid membrane of the chloroplast or in the membrane of some prokaryotes

Question 29

Photosystem 1 vs 2

Answer 29

Photosystem I (PS I): has 2 molecules of P700 chlorophyll a (700nm max absorption) at its reaction center and intervenes second in the light reaction.
Photosystem II (PS II): has 2 molecules of P680 chlorophyll a (680nm max absorption) at its reaction center and intervenes first in the light reaction.

Question 30

steps of photosystem?

Answer 30

2 electrons form H2O to P680-release O2
2 H creates proton gradient (ETC)
Elecron from p700 tranfered to second ETC
NADP reductase reduced to NADPH