Lecture 24 Flashcards

1
Q

Is glycolysis alone efficient for extracting energy?

A

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

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2
Q

Where is most of the energy harnessed in glycolysis?

A

the pyruvate molecules

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3
Q

How to get the most energy from glucose

A

fully oxidize glucose with oxygen

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4
Q

How to get more ATP from glucose without oxygen after glycolysis

A

fermentation pathways

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5
Q

The fate of pyruvate depends on what

A

kind of organism
specific cell type
availability of O2

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6
Q

Fermentation can create what molecules

A

Lactate or Ethanol, discarded as waste by cells

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7
Q

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

A

resets it, it oxidizes it back to NAD+

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8
Q

Lactate fermentation involves what electron transfer

A

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

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9
Q

Benefit of fermentation

A

replenishes the supply of NAD+ so glycolysis can continue

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10
Q

What uses the lactate fermentation pathway

A

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

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11
Q

Benefits of lactate in our bodies

A

can be converted back to glucose for energy

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12
Q

Lactate fermentation in our muscles occurs when

A

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

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13
Q

Cancer cells use

A

lactate fermentation

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14
Q

The warburg effect is

A

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

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15
Q

Lactate fermentation steps

A

Glucose -> pyruvate + NADH + LDH -> lactate

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16
Q

LDH in lactate fermentation

A

Lactate dehydrogenase

17
Q

Alcoholic fermentation steps

A

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

18
Q

ADH in ethanol fermentation is

A

alcohol dehydrogenase

19
Q

PDC in ethanol fermentation is

A

Pyruvate decarboxylase

20
Q

Different way to enter glycolysis without glucose

A

polysaccharides like starch (plants) or glycogen (animals)

21
Q

Entering glycolysis by starch or glycogen skips

A

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

22
Q

Can ezyme reactions be reversed?

A

If no energy is required for the reaction

23
Q

Why can some enzymatic reactions not run in reverse

A

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

24
Q

Why would you want to reverse glycolysis?

A

if glucose is running low

25
Gluconeogenesis is
reversed glycolysis to make glucose
26
Gluconeogenesis occurs by
different enzymes than glycolysis
27
Where does gluconeogenesis mainly occur
the liver to support body
28
Are most biosynthetic pathways a simple reverse of catabolism?
No
29
What reaction can run in reverse?
Ethanol fermentation, by oxidizing the ethanol this happens when we drink alcohol bc too much ethanol is toxic
30
Where does pyruvate oxidation occur
cytoplasm into the mitochondrial matrix
31
Pyruvate oxidation substrate
2 pyruvate
32
Pyruvate oxidation products
2 acetyl CoA 2 NADH (6ATP) 2 CO2