Lecture 24

Question 1

Is glycolysis alone efficient for extracting energy?

Answer 1

no, only makes 2 ATP which is only 3% of the total energy in a glucose molecule

Question 2

Where is most of the energy harnessed in glycolysis?

Answer 2

the pyruvate molecules

Question 3

How to get the most energy from glucose

Answer 3

fully oxidize glucose with oxygen

Question 4

How to get more ATP from glucose without oxygen after glycolysis

Answer 4

fermentation pathways

Question 5

The fate of pyruvate depends on what

Answer 5

kind of organism
specific cell type
availability of O2

Question 6

Fermentation can create what molecules

Answer 6

Lactate or Ethanol, discarded as waste by cells

Question 7

What does fermentation do to NADH that’s formed from glycolysis

Answer 7

resets it, it oxidizes it back to NAD+

Question 8

Lactate fermentation involves what electron transfer

Answer 8

involves the direct transfer of electrons from NADH to pyruvate to create lactate

Question 9

Benefit of fermentation

Answer 9

replenishes the supply of NAD+ so glycolysis can continue

Question 10

What uses the lactate fermentation pathway

Answer 10

Anaerobic microbes with glucose or lactose
Dairy products to make cheese and yogurt
Oxygen-deprived muscle cells

Question 11

Benefits of lactate in our bodies

Answer 11

can be converted back to glucose for energy

Question 12

Lactate fermentation in our muscles occurs when

Answer 12

the oxygen is used up too fast causing the hypoxic condition and making the lactate convert into more glucose to make more ATP

Question 13

Cancer cells use

Answer 13

lactate fermentation

Question 14

The warburg effect is

Answer 14

even in presence of O2, cancer cells rely on anaerobic pathways to get ATP called aerobic glycolysis

uses lactate pathway by up-regulation of enzymes causing glucose intake by cancer cells to be increased by the GLUT1 transporter

this allows tumors a growth advantage over normal tissue

Question 15

Lactate fermentation steps

Answer 15

Glucose -> pyruvate + NADH + LDH -> lactate

Question 16

LDH in lactate fermentation

Answer 16

Lactate dehydrogenase

Question 17

Alcoholic fermentation steps

Answer 17

Glucose -> pyruvate + H + PDC ->acetaldehyde + NADH + ADH -> ethanol

Question 18

ADH in ethanol fermentation is

Answer 18

alcohol dehydrogenase

Question 19

PDC in ethanol fermentation is

Answer 19

Pyruvate decarboxylase

Question 20

Different way to enter glycolysis without glucose

Answer 20

polysaccharides like starch (plants) or glycogen (animals)

Question 21

Entering glycolysis by starch or glycogen skips

Answer 21

the first ATP-dependent step (splitting into 2 G3P molecules), but still causes 2 net ATP bc ATP is used when forming starch or glycogen

Question 22

Can ezyme reactions be reversed?

Answer 22

If no energy is required for the reaction

Question 23

Why can some enzymatic reactions not run in reverse

Answer 23

because if the reaction required converting ATP, reversing is unlikely without other enzymes (different from the ones used to go in the forward direction)

Question 24

Why would you want to reverse glycolysis?

Answer 24

if glucose is running low

Question 25

Gluconeogenesis is

Answer 25

reversed glycolysis to make glucose

Question 26

Gluconeogenesis occurs by

Answer 26

different enzymes than glycolysis

Question 27

Where does gluconeogenesis mainly occur

Answer 27

the liver to support body

Question 28

Are most biosynthetic pathways a simple reverse of catabolism?

Answer 28

No

Question 29

What reaction can run in reverse?

Answer 29

Ethanol fermentation, by oxidizing the ethanol

this happens when we drink alcohol bc too much ethanol is toxic

Question 30

Where does pyruvate oxidation occur

Answer 30

cytoplasm into the mitochondrial matrix

Question 31

Pyruvate oxidation substrate

Answer 31

2 pyruvate

Question 32

Pyruvate oxidation products

Answer 32

2 acetyl CoA
2 NADH (6ATP)
2 CO2