Cellular Respiration

Question 1

-delta G per mole glucose

Answer 1

-686kcal/mol

Question 2

dehydrogenation

Answer 2

high energy H atoms removed from organic molecules

Question 3

aerobic respiration overview

Answer 3

1. glycolysis
2. pyruvate decarbooxylation
3. Kreb/CAC/Tricarboxylic acid cycle
4. ETC = oxidative phosporylation

final products = O2 + H2O

Question 4

glycolysis, products and overview

Answer 4

• decomposition of glucose into pyruvate in CYTOSOL
• NET: 2 ATP + 2 NADH + 2 pyruvate (+ 2 H2O + 2 H2)
• make 4 ATP, but put in 2, so net 2
• substrate level phosphorylation
• hexokinase adds P to glucose, PFK adds 2nd – fructose-1,6-bisphosphate

Question 5

substrate level phosphorylation

Answer 5

direct enzymatic transfer of transfer of P to ADP; no extraneous carriers needed

Question 6

role of hexokinase

Answer 6

in glycolysis, it puts a P onto glucose so that it cannot diffuse out - tricks gradient

Question 7

role of PFK

Answer 7

once hexokinase adds one P to glucose, it adds a second to make fructose-1,6-bisphosphate IRREVERSIBLE! committed to glycolysis

Question 8

pyruvate decarboxylation

Answer 8

• MITOCHONDRIA
• pyruvate –> acetyl CoA + NADH + CO2
• net is 2 of each of those bc 2 pyruvate per glucose
• PDC = catalyst (pyruvate dehydrogenase complex)

Question 9

PDC

Answer 9

pyruvate dehydrogenase complex, catalysts of pyruvate decarboxylation which converts pyruvate –> acetyl CoA + NADH + CO2

Question 10

Krebs/CAC/TCA cycle

Answer 10

acetyl CoA merges with oxaloacetate –> citrate (7 intermediates)
each acetyl CoA produces 3 NADH + 1 FADH2 + 1 ATP (SUBSTRATE PHOS)
-animals exhale the CO2
-Mitochodrial Matrix
-NET = 6 NADH + 2 FADH2 + 2 ATP + 2CO2

Question 11

ETC

Answer 11

electron transport chain in inner membrane/cristae (folds to increase surface area)

• oxidative phosphorylation
• O2 = final e- acceptor, combines with native H+ to form H2O
• NADH and FADH2 = coenzymes, more H+ pumped across per NADH (3:2)
• ATP synthase uses pH/elec gradient to make ATP as it shuttles H+ back into the matrix

Question 12

cristae

Answer 12

folds in the inner membrane of the mitochondria to increase SA for ETC oxidative phosphorylation

Question 13

oxidative phosphorylation

Answer 13

ADP –> ATP from NADH + FADH2 via passing off electrons through various carrier proteins; energy does not accompany the P group but comes from the e- in ETC that establishes the H+ gradient which then supplies energy to ATP synthase

Question 14

CoQ

Answer 14

Coenzyme Q - ubiquinone; soluble carrier dissolved in membrane, can be fully oxidized/reduced

Question 15

CytC

Answer 15

cytochrome C: used for genetic relationships because common to many organisms; non protein parts (Fe) - donate/accept e-
transfers electrons between complexes III and IV

Question 16

total energy of aerobic respiration

Answer 16

1 glucose ~36ATP (38 in prok) but actual yield more like 32 based on mitochondrial efficiency
prokaryotes = no mitochondria to transport pyrute into so they dont lose 2 ATP to active transport because they use cell membrane for respiration

Question 17

chemiosmosis

Answer 17

he movement of ions across a selectively permeable membrane, down their electrochemical gradient. More specifically, it relates to the generation of ATP by the movement of hydrogen ions across a membrane during cellular respiration.

Question 18

ATP synthase

Answer 18

enzyme that makes ATP by chemiosmosis. It allows protons to pass through the membrane and uses the kinetic energy to phosphorylate ADP, making ATP

Question 19

what does Krebs produce and what happens to them

Answer 19

NADH/FADH2 - they are oxidized (lose electrons)

Question 20

anaerobic respiration, overview

Answer 20

• in cytosol
• glycolysis and fermentation
• why? w/o O2, NADH accumulates and no NAD+, so no glycolysis or ATP production
• fermentation = alcohol in plants, fungi, bacteria & lactic acid in human muscle cells, microorgs, etc

Question 21

alcohol fermentation

Answer 21

pyruvate –> acetylaldehyde + CO2
acetylaldehyde + NADH –> ethanol + NAD+
-acetylaldehyde = final e- acceptor (it is reduced) to form ethanol; analogous to O2 being final e- acceptor

Question 22

lactic acid fermentation

Answer 22

pyruvate + NADH –> lactate + NAD+
lactate goes to liver for conversion back to glucose once surplus ATP available
Lactate dehydrogenase catalyzes the interconversion of pyruvate and lactate with concomitant interconversion of NADH and NAD+

Question 23

facultative anaerobes

Answer 23

tolerate O2, but usually don’t use it

Question 24

obligate anaerobes

Answer 24

cannot be in presence of O2

Question 25

priority of energy sources

Answer 25

1. glucose 2. other carbs 3. fats 4. proteins (2,3,4 - first converted to glucose or glucose inetrmediates and then degraded in gylcolysis or CAC)

Question 26

other carbs as energy source

Answer 26

hydrolyzed into monosaccharides, most of which can be converted to glucose or gluucose intermediates; glycogen is source - all cells capable of producing/storing it but muscle and liver haver large amounts

Question 27

PFK = phosphofructokinase

Answer 27

catalyzes commitment step of glycolysis, fructose-6-phosphate to fructose-1,6-bisphosphate

Question 28

insulin, glucagon

Answer 28

insulin - stores glucose as glycogen; glucagon - turns on glycogen --> glucose degredation insulin activates PFK2 and glucagon inhibits it; when glucose is high, insulin -- glycolysis is stimulated and gluconeogenesis is inhibited.

Question 29

fats as alternative energy source

Answer 29

- carbons more reduced state, so more energy (9 kcal/mol vs 4 in carb adn pro) - lipases in adipose tissue are sensitive to glucagon, which is active hormone when glucose levels low - glycerol --> PGAL, enters glycolysis - FA --> 1 acetyl CoA per every 2 C in FA chain - costs 2 ATP to activate FA in cytoplasm, transport into mitochondria - beta-oxidation: for every cut, 1 acetyl CoA-->krebs-->1 NADH + 1 FADH2 - unsaturated FA: 1 fewer FADH2 for each double bond

Question 30

beta oxidation

Answer 30

process by which fatty acid molecules are broken down in the mitochondria to generate acetyl-coA, which enters the citric acid cycle, and NADH and FADH2, which are used by the electron transport chain.

Question 31

protein as alternative energy source

Answer 31

least desirable most aa are deaminated in liver, converted to pyruvate or acetyl CoA or other CAC intermediate and then enter respiration oxidative deamination removes ammonia molecule directly from aa (ammonia = toxic to vertebrates - fish excrete it, birds/insects - uric acid, mammals - urea)