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Biochemistry > Lecture 20 - Glycolysis (Exam 2) > Flashcards

Lecture 20 - Glycolysis (Exam 2) Flashcards

1
Q

During a sprint, are you utilizing oxygen for glycolysis?

A

No, oxygen is used for longer endurance in the transport chain.

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2
Q

Glycolysis involves a sequence of reactions that metabolizes 1 molecules of _______ to 2 molecules of _______ and generates 2 _______.

A

Glucose
Pyruvate
ATP

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3
Q

(AEROBIC/ANAEROBIC) is the process without oxygen and used in glycolysis.

A

Anaerobic

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4
Q

Pyruvate can be completely oxidized under aerobic conditions, which generates much more ______.

A

ATP

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5
Q

Is glycolysis useful for short bursts or long runs? What about the transport chain?

A

Glycolysis is good for short bursts of energy.

Transport chain is good for longer runs/endurance.

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6
Q

After glycolysis is done and we have pyruvate, what are the three fates that can occur to pyruvate?

A

Fermentation
Lactate
Complete oxidation (mitochondria)

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7
Q

_______ is a common and most important fuel.

A

Glucose

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8
Q

In mammals, ________ is the ONLY fuel that the brain uses under conditions of non-starvation.

A

Glucose

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9
Q

In mammals, glucose is the ONLY fuel that ________ can use.

A

RBCs

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10
Q

Pyruvate and lactate can be salvaged an resynthesized to glucose via _________.

A

Gluconeogenesis

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11
Q

What are sources of glucose in the diet?

A

Disaccharides (especially sucrose and lactose)
Starch
Glycogen

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12
Q

The job of the _______ is to make sure all parts of the body gets their favorite type of fuel.

A

Liver

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13
Q

When blood glucose is down (i.e., in times of fasting) _______ is used.

A

Glycogen

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14
Q

Glucose uptake occurs via what type of diffusion?

A

Facilitated diffusion

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15
Q

Glucose uptake occurs via protein transporters called _______.

A

GLUTs (Glucose Transporters)

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16
Q

This type of GLUT is ubiquitous but expressed highly in the brain and RBCs. It has high affinity. (Km 1 mM)

A

GLUT1

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17
Q

This type of GLUT is the main transporter in the liver and pancreas. It has low affinity. (Km 10 mM)

A

GLUT2

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18
Q

This type of GLUT is the main transporter in neurons. It has high affinity. (Km 1 mM)

A

GLUT3

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19
Q

This type of GLUT is present in skeletal muscle, heart, and adipose tissue. It is the only one that is insulin dependent. It’s stored in vesicle right below the plasma membrane. (Km 5 mM)

A

GLUT4

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20
Q

Where does glycolysis occur?

A

In the cytoplasm of eukaryotic cells

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21
Q

Glycolysis is divided into 2 stages, which are…

A

1) Trapping of glucose and its cleavage into 2 interconvertible 3-carbon molecules
2) Generation of ATP

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22
Q

The first stage of glycolysis begins with the phosphorylation of glucose by ________ and ends with the isomerization of _________ ________ to _________ _________.

A

Hexokinase
Dihydroxyacetone phosphate
Glyceraldehyde 3-phosphate

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23
Q

Stage 1 of glycolysis involves 5 steps. The trapping of glucose and preparation phase generates no ATP, but consumes _____ ATP.

A

2

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24
Q

Stage 1 of glycolysis consists of three reactions, which are…

A

Phosphorylation
Isomerization
2nd Phosphorylation

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25
Q

The strategy of stage 1 glycolysis is to trap the glucose in cell and form a compound that can be readily cleaved into…

A

2 phosphorylated three-carbon units

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26
Q

In stage 1 glycolysis, step 1 – Glucose is phosphorylated to __________ using enzyme _________ (in all tissues) and _________ (in liver). _____ is consumed.

A

Glucose-6-phosphate (G6P)
Hexokinase
Glucokinase
ATP

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27
Q

In stage 1 glycolysis, step 2 – G6P is isomerize to __________ using enzyme ___________.

A

Fructose-6-phosphate (F6P)

Phosphoglucoisomerase

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28
Q

In stage 1 glycolysis, step 3 – F6P is phosphorylated to ___________ using enzyme ___________ (rate limiting enzyme). ______ is consumed.

A

Fructose-1,6-bisphosphate
Phosphofructokinase
ATP

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29
Q

In stage 1 glycolysis, step 4 – F1,6BP is broken down to ___________ and ________ _________ using enzyme _________.

A 
Glyceraldehyde-3-phosphate (G3P) 
Dihydroxyacetone phosphate (DHAP)
Aldolase
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30
Q

In stage 1 glycolysis, step 5 – DHAP isomerized to G3P using enzyme ________ _______ ________.

A

Triose phosphate isomerase

31
Q

In the second stage of glycolysis, energy harnessed in G3P is used to form ______.

A

ATP

32
Q

What is the rate limiting enzyme of glycolysis?

A

Phosphofructokinase

33
Q

In stage 2 of glycolysis, step 1 – Oxidative phosphorylation of G3P to form __________ is done by G3P _________. _____ is reduced to ______.

A

1,3-Bisphosphoglycerate (1,3-BPG)
Dehydrogenase
NAD+
NADH

34
Q

1,3-BPG has high _______-_______ potential.

A

Phosphoryl-transfer

35
Q

NADH contains a pair of “high energy” _______. These are sent to the electron transport chain (ETC), play role in oxidative phosphorylation (OXPHOS).

A

Electrons

36
Q

In stage 2 glycolysis, step 2 – ________ _______ converts 1,3-BPG to __________. _____ is phosphorylated to _____ to form this, via substrate transfer.

A

Phosphoglycerate kinase
3-Phosphoglycerate (3-PG)
ADP
ATP

37
Q

In stage 2 glycolysis, step 3 – ________ ________ moves phosphate from 3rd position in 3-PG to the 2nd position to form __________.

A

Phosphoglycerate mutase

2-Phosphoglycerate (2-PG)

38
Q

In stage 2 glycolysis, step 4 – Dehydration of 2-PG by ________ forms _________, an enol with high phosphoryl-transfer potential (unstable).

A

Enolase

Phosphoenolpyruvate (PEP)

39
Q

In stage 2 glycolysis, step 5 – ________ ________ transfers phosphoryl group from PEP to ______ to form ______. PEP is converted from unstable enol to ________, a stable ketone. This step is irreversible.

A

Pyruvate kinase
ADP
ATP
Pyruvate

40
Q

What is required for stage 2 glycolysis to operate correctly?

A

It must go through the steps 2 times

41
Q

Pyruvate can be reduced to lactate, with the regeneration of ______ (low oxygen).

A

NAD+

42
Q

Pyruvate can be oxidized aerobically via the citric acid cycle after first undergoing an oxidative decarboxylation to form ______ ______.

A

Acetyl CoA

43
Q

_______ is a disaccharide of glucose and fructose.

A

Sucrose

44
Q

_______ is a disaccharide of glucose and galactose.

A

Lactose

45
Q

Fructose and galactose are converted into ________ ________.

A

Glycolytic intermediates

46
Q

Fructose is quickly turned to ______ in times of high energy.

A

Fat

47
Q

What is the net generation of ATP in glycolysis?

A

2 ATP (2 consumed, 4 made)

48
Q

In fructose metabolism, fructose turns to fructose 1-phosphate with the help of _________ and ATP.

A

Fructokinase

49
Q

In the fructose 1-phosphate step of fructose metabolism, it turns to glyceraldehyde and dihydroxyacetone phosphate with the help of what enzyme?

A

Fructose 1-phosphate aldolase

***Remember dihydroxyacetone phosphate can be used in glycolysis

50
Q

In fructose metabolism, once glyceraldehyde is reached, the enzyme triose kinase and ATP create…

A

Glyceraldehyde 3-phosphate

***Used in glycolysis

51
Q

What are the major regulatory enzymes of glycolysis?

A

Hexokinase (trapping glucose)
Phosphofructokinase (rate-limiting step)
Pyruvate kinase (generates ATP)

52
Q

What is the goal of glycolysis in muscle?

A

To generate ATP during activity

53
Q

What is the goal of glycolysis in liver?

A

To maintain blood glucose levels

To provide building blocks for other pathways

54
Q

This is a side product of glycolysis that is only present in the liver.

A

F-2,6-BP

55
Q

In the liver, what does F-2,6-BP activate?

A

Phosphofructokinase

56
Q

In the liver, phosphofructokinase can be inhibited by what?

A

Citrate

57
Q

In the liver there is no hexokinase, there is ________. This is not inhibited by glucose 6-phosphate (glucose permanently trapped).

A

Glucokinase

58
Q

Lactose intolerance is an inability to metabolize lactose. Drinking milk causes disturbances in GI function. It is caused by a deficiency in the enzyme _______ (which breaks down lactose to glucose and galactose).

A

Lactase

59
Q

Lactose intolerance is an inability to metabolize lactose. Drinking milk causes disturbances in GI function. It is caused by a deficiency in the enzyme _______ (which breaks down lactose to glucose and galactose).

A

Lactase

60
Q

________, a commonly used sweetener, is a component of sucrose and high fructose corn syrup. Excessive levels of this are linked to fatty liver, insulin sensitivity, obesity, and type 2 diabetes.

A

Fructose

61
Q

Actions of fructokinase and triose kinase bypass the most important regulatory step in glycolysis, the ____________-catalyzed reaction.

A

Phosphofructokinase

62
Q

Fructose-derived G3P and DHAP are processed by glycolysis to ________ and ________ in an unregulated fashion.

A

Pyruvate

Acetyl CoA

63
Q

Excess acetyl CoA converted to fatty acids, which can be transported to adipose tissue to form __________, resulting in obesity. Liver also begins to accumulate fatty acids, resulting in fatty liver.

A

Triacylglycerols

64
Q

Activity of the fructokinase and triose kinase can deplete the liver of ______ and inorganic phosphate, compromising liver function.

A

ATP

65
Q

Disruption of galactose metabolism is called…

A

Galactosemia

66
Q

Classic galactosemia (most common form) is an inherited deficiency in…

A

Galactose 1-phosphate uridyl transferase

67
Q

In classic galactosemia, afflicted ________ fail to thrive.

A

Infants

68
Q

The diagnostic criterion of galactosemia is the absence of the ________ in red blood cells. The treatment is to remove _________ (and lactose) from diet.

A

Transferase

Galactose

69
Q

In galactosemia, although elimination of ________ from diet prevents liver disease and cataract development, majority of patients still suffer from central nervous system malfunction, most commonly a delayed acquisition of language skills.

A

Galactose

70
Q

Cataract is the clouding of the normally clear lens of the eye. If the transferase is not active in the lens of the eye, the presence of _______ ______ causes the accumulating galactose to be reduced to ________.

A

Aldose reductase

Galactitol

71
Q

_______ display enhanced rates of glucose uptake and glycolysis.

A

Tumors

72
Q

Rapidly growing tumor cells metabolize glucose to lactate even in the presence of oxygen, a process called…

A

Aerobic glycolysis (Warburg effect)

73
Q

Tumors with a high _______ uptake are particularly aggressive, and the cancer is likely to have a poor prognosis.

A

Glucose

Biochemistry (10 decks)

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