u3: glycolysis, pyruvate oxidation, krebs cycle

Question 1

in glycolysis, how much of the free energy in glucose is converted into ATP

Answer 1

• 2.2%
• 62 kJ in two moles of ATP/2870 kJ in glucose

Question 2

in glycolysis, how much of the free energy in glucose is converted into pyruvate

Answer 2

75%

Question 3

how does pyruvate go from the cytoplasm to the mitochondrial matrix?

Answer 3

• diffuses through outer membrane via large pores
• pyruvate-specific membrane carrier for inner membrane

Question 4

steps of pyruvate oxidation

Answer 4

1. decarboxylation: carboxyl (COO-) is removed to form CO2 waste prod’t
2. remaining 2 carbon molecules are oxidized to make acetyl group
3. dehydrogenation: turns NAD+ into NADH, releases one H+
4. acetyl group reacts w/ coenzyme A = acetyl-CoA

Question 5

how many turns of the citric acid cycle does each glucose cause?

Answer 5

• two turns
• 1 glucose = 2 pyruvate = 2 acetylCoA in the cycle

Question 6

what happens to the original glucose by the end of the krebs cycle?

Answer 6

• original carbon/oxygen atoms are in the form of CO2 and get released as waste
• original hydrogens are carried by NADH and FADH2

Question 7

autotrophs

Answer 7

• make complex organic compounds from simple organic compounds
• use external energy source; sunlight

Question 8

heterotrophs

Answer 8

consume external organic compounds to produce energy

Question 9

aerobes vs anaerobes

Answer 9

• aerobes utilize O2 to oxidize substances in order to obtain energy
• anaerobes do not utilize O2 for energy

Question 10

types of aerobes

Answer 10

• obligate aerobes
• facultative aerobes

Question 11

types of anaerobes

Answer 11

• obligate anaerobes
• facultative anaerobes

Question 12

facultative aerobes vs facultative anaerobes

Answer 12

• facultative aerobes: use O2 but have anaerobic methods, yeast/some human cells
• facultative anaerobes: can be exposed to O2, staphylococcus, streptococcus

Question 13

phosphorylation + its types

Answer 13

• transfer of a phosphate group
• substrate-level
• oxidative

Question 14

first step of glycolysis

Answer 14

glucose is phosphorylated so it cant diffuse out of the cell

Question 15

how many reactions does glycolysis consist of

Answer 15

10

Question 16

wht happens to acetyl-CoA in the krebs cycle

Answer 16

acetyl-CoA (2C compound) is oxidized into CO2

Question 17

steps of krebs cycle

Answer 17

1. acetyl group transferred to oxaloacetate = citrate
2. citrate rearragned into isocitrate
3. isocitrate oxidized. NAD+ in, NADH + CO2 out
4. ketoglutarate oxidized. NAD+ in, NADH + CO2 out
5. GDP + Pi becomes GTP (carries energy like ATP)
6. FAD in, FADH2 out
7. NAD+ in, NADH out
8. 4 carbon oxaloacetate regenerated

Question 18

glycolysis net reaction

Answer 18

Glucose + 2 ADP + 2 Pi + 2 (NAD+) 🡪
2 pyruvate + 2 ATP + 2 NADH + 2 (H+)

Question 19

pyruvate oxidation net reaction

Answer 19

2 pyruvate + 2 (NAD+) + 2CoA
🡪
2 acetyl-CoA + 2 NADH + 2(H+) + 2 CO2

Question 20

citric acid/kreb’s cycle net reaction

Answer 20

2 acetyl-CoA + 6 NAD + 2 FAD + 2 ADP + 2 Pi
🡪
6 NADH + 6 (H+) + 2 FADH2 + 4 CO2 + 2ATP + 2CoA