metabolic pathways and cellular respiration

Question 1

explain the concept of coupling reactions

Answer 1

• exergonic drives endergonic

- see notebook for example

Question 2

be able to tell what the letters ‘ATP’ stand for

Answer 2

Adenosine Tri-Phosphate

Question 3

why is ATP a high energy compound?

Answer 3

it has very unstable bonds between each phosphate group, which are also high energy

Question 4

explain how ATP transfers energy

Answer 4

hydrolysis (phosphorylation) of ATP releases energy because it relieves repulsion of negative charges and it increases energy

Question 5

define oxidation and reduction

Answer 5

LEO goes GER

oxidation: the loss of electrons (or H ions)
reduction: the gain of electrons (or H ions)

Question 6

describe the role NAD+ plays in cellular respiration, and be able to tell what NAD stands for

Answer 6

NAD: Nicotinamide Adenine Di-nucleotide

NAD+ is an electron carrier in cellular respiration

Question 7

give a summary/overview of the movement of electrons from food molecules all the way to O2

Answer 7

electron transfer to power ATP production

1. catabolic enzymes pull off electrons from food molecules
2. pass electrons to NAD+/FAD, turn into NADH/FADH2
3. NADH/FADH2 gives electrons to O2 to make H2O and release energy
4. energy used to make ATP

Question 8

recognize the overall chemical reaction of cellular respiration. identify which reactant gets oxidized and which gets reduced. (or which product is in the reduced form, which is in the oxidized form)

Answer 8

C6H12O6 + 6O2 –> 6CO2 + 6H2O + (energy)

the left side is oxidized, and the right side is reduced

Question 9

know the 4 phases of cellular respiration and where they take place

Answer 9

1. glycolysis in cytosol
2. pyruvate oxidation in the mito matrix
3. citric acid cycle in mito matrix
4. oxidative phosphorylation in inner mito memebrane

Question 10

know how much ATP, NADH, and FADH2 are made in each phase

Answer 10

1. glycolysis: 2 ATP and 2 NADH
2. pyruvate oxidation: 2 NADH
3. citric acid cycle: 2 ATP, 10 NADH, and 2 FADH2
4. oxidative phosphorylation: 32 ATP

Question 11

be able to name the final product of glycolysis. how many are produced by putting 1 glucose molecule into glycolysis?

Answer 11

2 pyruvate molecules are made by putting one glucose molecule through glycolysis.

Question 12

be able to describe the 2 stages of glycolysis

Answer 12

the glucose is put in, then:

• energy investment phase: uses 2 ATP, 5 reactions
• energy payoff phase: 4 ATP and 2 NADH are made, 5 reactions

Question 13

net gain of ATP and NADH from one round of glycoysis

Answer 13

ATP: 2
NADH: 2

Question 14

be able to name and recognize the molecule that pyruvate must be converted to before entering the citric acid cycle (and the energy yield from the reaction that produces it)

Answer 14

pyruvate must be converted to acetyl co-enzyme A. see notebook for drawing. the energy yield of pyruvate oxidation is 2 NADH.

Question 15

know the net gain of ATP, NADH, and FADH2 from feeding acetyl Co-As into the citric acid cycle

Answer 15

net yield of citric acid cycle: 2 ATP, 6 NADH, and 2 FADH2

Question 16

be able to tell what 2 molecules carry electrons from glycolysis and the citric acid cycle to the electron transport chain

Answer 16

NAD+ and FAD

Question 17

be able to describe where in the cell the electron transport chain occurs and be able to explain how the transfer of electrons down that chain create a proton (H+) gradient

Answer 17

electron transport chain is a series of proteins embedded in the inner mitochondria membrane. it catalyzes redox reactions.

• electrons release free energy as they step through the proteins, ending on O2
• electron stepping energy released for active transport
• [H+] imbalance across the inner mitochondria membrane = electrochemical gradient, aka the proton motive force. this force possesses high potential energy

Question 18

be able to explain chemiosmosis is (coupling of electron transport to ATP synthesis)

Answer 18

=passive transport of H+ ions back into the matrix, very exergonic
-exergonic movement powering the endergonic reaction of ATP (ADP + Pi –> ATP)

Question 19

be familiar with the structure of the ATP synthase protein and the mechanisms of the subunit

Answer 19

-found in the inner mitochondria membrane
Fo subunit: in membrane, H+ transporter, path for H+ to get into matrix
F1 subunit: in matrix, catalytic subunit
-H+ binds to Fo, it rotates, powers F1

Question 20

know the approximate net gain of ATP from oxidative phosphorylation

Answer 20

each NADH fed into ETC gets approximately 2.5 ATP
10 NADH x 2.5 = about 25 ATP
each FADH2 fed into ETC gets approximately 1.5 ATP
2 FADH2 x 1.5 = 3 ATP
TOTAL: approximately 28 ATP

Question 21

know the maximum yield of ATP’s from one glucose molecule being processed through all 4 steps of cellular respiration

Answer 21

maximum of 32 ATP/glucose molecule

Question 22

predict the consequences of blocking any one of the steps of the ETC with poisons like rotenone or cyanide

Answer 22

poisons like rotenone or cyanide inhibit the electron transport of NADH. this then leaves no electrons to attach to O2 to make water for the body