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Biochemistry > Exam 2 Lecture 15 Glycolysis > Flashcards

Exam 2 Lecture 15 Glycolysis Flashcards

1
Q

glycolysis occurring in the absence of O2:

A

provides ATP quickly and for short amount of time (more efficient in sprinting)

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2
Q

glycolysis metabolizes: anaerobic

1 molecule of glucose gets:

A

1 molecule of glucose to 2 molecules of pyruvate and generates 2 molecules of ATP

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3
Q

glycolysis metabolizes: aerobic

1 molecule of glucose gets:

A

2 pyruvate, 2 ATPs, 2 NADH; pyruvate enters the mitochondria to enter TCA cycle to generate more ATP

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4
Q

is anaerobic of aerobic glycolysis more efficient?

A

complete oxidation more energy efficient than anaerobic glycolysis

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5
Q

sources of glucose in diet:

A
  1. disaccharides (present in foods we consume): sucrose made from fructose and glucose and lactose made from galactose and glucose
  2. starch (plant)
  3. glycogen (animal)
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6
Q

under conditions of non-starvation, the brain uses _ as fuel

A

glucose

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7
Q

_ is the only fuel that RBCs can use

A

glucose

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8
Q

how does gluconeogenesis occur?

A

pyruvate and lactate are salvaged and re-synthesized to glucose

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9
Q

glucose uptake occurs via protein transporters called _; ECF into cell’s cytoplasm

A

glucose transporters (GLUTs)

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10
Q

Types of GLUTs:

ubiquitous but expressed highly in brain and RBCs. High affinity to glucose and unregulated

A

GLUT1

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11
Q

Types of GLUTs:

main transporter in liver (pancreas); low affinity to glucose and unregulated

A

GLUT2

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12
Q

Types of GLUTs:

main transporter in neurons; high affinity to glucose and unregulated

A

GLUT3

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13
Q

Types of GLUTs:

present in skeletal muscle, heart, adipose tissue; insulin dependent (regulated by insulin)

A

GLUT4

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14
Q

GLUT1 has a Km of _ which is advantageous because?

A

Km = 1 mM (high affinity) advantageous because even if there is very little glucose, will still pick it up because it is sensitive to glucose

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15
Q

RBCs use only glucose because

A

there is no mitochondira ie no oxygen

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16
Q

_ is the center of glycolysis

A

liver

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17
Q

GLUT2 has Km of _ which makes sense because:

A

Km = 10 mM (low affinity) makes sense because liver (pancreas) is a high capacity system for glucose

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18
Q

GLUT3 has Km of _

A

Km = 1 mM (high affinity)

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19
Q

GLUT4 has Km of _

A

Km = 5 mM

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20
Q

exercise enhances which GLUT?

A

GLUT4

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21
Q

stored in vesicles under the plasma membrane (fusion of vesicle to plasma membrane); present in sub-specialized tissues describes which GLUT?

A

GLUT4

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22
Q

GLUT1-3 uses _ which is why they are unregulated

A

gradients

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23
Q

glycolysis happens where?

A

occurs in the cytoplasm of eukaryotic cells

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24
Q

what are the 2 stages of glycolysis?

A
  1. trapping of glucose and its cleavage into 2 inter-convertible 3-carbon molecules
  2. generation of ATP
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25
Q

the 1st stage of glycolysis begins with _ of glucose and ends with _

A

1st stage of glycolysis begins with the PHOSPHORYLATION of glucose and ends with the isomerization of dihydroxyacetone phosphate to GAP IE GLYCERALDEHYDE 3-PHOSPHATE

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26
Q

Trapping of glucose and preparation phase:

what is consumed and generated?

A

2 ATPs consumed and no ATP generated

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27
Q

Trapping of glucose and preparation phase:

consists of 3 reactions:

A
  1. phosphorylation
    2/ isomerization
  2. and a second phosphorylation
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28
Q

Trapping of glucose and preparation phase:

strategy of this phase is to:

A

TRAP THE GLUCOSE in the cell and form a compound that can be readily cleaved into 2 PHOSPHORYLATED 3-CARBON UNITS

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29
Q

Steps 1-5 of stage 1 of glycolysis:

at which step is glucose phosphorylated to G6P, ATP is consumed, and either enzyme hexokinase or glucokinase is responsible?

A

step 1

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30
Q

hexokinase is found where?

A

in all tissues

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31
Q

glucokinase is found where?

A

in liver

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32
Q

which enzymes catalyze irreversible reactions?

A
  1. glucokinase/hexokinase
  2. PFK-1
  3. pyruvate kinase
33
Q

Steps 1-5 of stage 1 of glycolysis:

at which step is G6P isomerized to F6P

A

step 2

34
Q

which enzyme converts glucose into G6P?

A

either hexokinase or glucokinase

35
Q

which enzyme converts G6P into F6P?

A

phosphoglucoisomerase

36
Q

Steps 1-5 of stage 1 of glycolysis:

at which step does F6P phosphorylated to F1,6BP and ATP is consumed?

A

step 3 rate limiting step

37
Q

which enzyme converts F6P into F1,6BP?

A

phosphofructokinase (rate limiting enzyme of glycolysis)

38
Q

Steps 1-5 of stage 1 of glycolysis:

at which step is F1,6BP broken down to glyceraldehyde-3-phosphate (G3P) and dihydroxyacetone phosphate (DHAP)

A

step 4 (reversible)

39
Q

which enzyme breaks F1,6BP into G3P and DHAP?

A

aldolase

40
Q

Steps 1-5 of stage 1 of glycolysis:

at which step is DHAP isomerized to G3P?

A

step 5

41
Q

which enzyme isomerizes DHAP into G3P ?

A

triose phosphate isomerase

42
Q

stage 2 of glycolysis is when:

A

energy is harnessed in GAP used to form ATP

43
Q

Steps 1-5 of stage 2 of glycolysis:

at which step does oxidative phosphorylation of GAP to form 1,3-BPG and NAD+ is reduced to NADH happen?

A

step 1 of stage 2

44
Q

which enzyme coverts GAP into 1,3-BPG

A

GAPDH and reduces NAD+ to NADH

45
Q

NADH contains a pair of “high energy” e-s that are sent to:

A

ETC; play a role in oxidative phosphorylation

46
Q

Steps 1-5 of stage 2 of glycolysis:

at which step is 1,3-BPG is converted into 3-PG and ADP is phosphorylated to form ATP (ATP is synthesized) and 3-PG?

A

step 2 of stage 2

47
Q

what enzyme converts 1,3-BPG into 3-PG?

A

phosphoglycerate kinase

48
Q

Steps 1-5 of stage 2 of glycolysis:

at which step is 3-PG converted to 2-PG?

A

step 3 of stage 2

49
Q

what enzyme converts 3-PG to 2-PG?

A

phosphoglycerate mutase

50
Q

Steps 1-5 of stage 2 of glycolysis:

at which step is 2-PG dehydrated to form PEP and the phosphoryl group is transferred from PEP to ADP to form ATP?

A

step 4 of stage 2

51
Q

PEP:

A

an enol with HIGH PHOSPHORYL-TRANSFER POTENTIAL (unstable)

52
Q

what is the enzyme that dehydrates 2-PG into PEP?

A

enolase

53
Q

Steps 1-5 of stage 2 of glycolysis:

at which step is PEP converted from unstable enol to pyruvate, a stable ketone?

A

step 5 of stage 2

54
Q

what enzyme converts PEP to pyruvate?

A

pyruvate kinase IRREVERSIBLE STEP

55
Q

what is the fate of pyruvate?

A
  1. formation of NAD+ to regenerate glycolysis and form lactate
  2. formed into acetyl-CoA to enter TCA (lipid metabolism)
  3. converted into ethanol (fermentation) for microorganisms
56
Q

glycolysis will stop if _ is not regenerated

A

NAD+

57
Q

sucrose is a disaccharide of:

A

glucose and fructose

58
Q

lactose is a disaccharide of:

A

galactose and glucose

59
Q

fructose and galactose can be converted into _

A

glycolytic intermediates

60
Q

fructose is quickly turned into _ in times of high energy, why?

A

fat; fructose metabolism lacks rate limiting step (designed to bypass rate limiting step) and is making fats disproportionally

61
Q

UDP attached to sugar means:

A

a synthetic pathway; it is indirect

62
Q

the goal of regulation of glycolysis in muscle is:

A

to generate ATP during activity; ATP levels regulate glycolysis

63
Q

the goal of regulation of glycolysis in liver is:

A

to maintain blood glucose levels and provide building blocks for other pathways

64
Q

phosphofructokinase is activated by _ and inhibited by _

A

activated by F-2,6-BP and inhibited by citrate

65
Q

glucokinase is not inhibited by G6P which means:

A

glucose permanently trapped

66
Q

pyruvate kinase is regulated by _

A

allosteric effectors and coavalent modification

67
Q

high blood glucose level want to _ pyruvate kinase which can be achieved by high levels of _ to inhibit glycolysis

A

want PHOSPHORYLATE pyruvate kinase which is achieved by high levels of ATP

68
Q

low blood glucose level want to _ pyruvate kinase which can be achieved by _ which stimulates glycolysis

A

want to DEPHOSPHORYLATE pyruvate kinase which is stimulated by F1,6-BP

69
Q

why is hexokinase Km (very) low?

A

means high affinity for glucose. Hexokinase is present in every cell so needs to be able to detect even the smallest amount of glucose

70
Q

why is glucokinase Km high?

A

mean low affinity for glucose. Glucokinase is present in liver and liver is constantly presented with glucose bc of what we eat and is focuses on distributing glucose

71
Q

How does one result in having obesity and/or a fatty liver?

A
  1. fructokinase and triose kinase bypass the rate limiting step in glycolysis: the phosphofructokinase-catatlyzed rxn
  2. fructose derived G3P and DHAP are processed by glycolysis to pyruvate and acteyl CoA in an UNREGULATED fashion
  3. Excess acetyl CoA is converted into fatty acids which can be transported to adipose tissue to form triacylglycerols resulting in obesity
  4. Liver also begins to accumulate fatty acids resulting in a fatty liver
72
Q

what is lactose intolerance caused by?

A

deficiency in enzyme lactase

73
Q

disruption of galactose metabolism is called _

A

galactosemia

74
Q

CLASSIC GALCTOSEMIA is an inherited deficiency in _ activity

A

galactose 1-phosphate uridyl transferase activity

75
Q

absence of galactose 1-phosphate uridyl transferase in _ is a diagnostic criterion

A

RBCs

76
Q

How does the onset of cataracts occur?

A

Galactose not normally entering glycolysis because its been reduced to GALACTITOL which is not soluble so deposits around the lens of the eye

77
Q

rapidly growing tumor cells metabolize glucose to lactate in a process called

A

aerobic glycolysis or the Warburg effect

78
Q

visualization of tumor effectiveness of treatment is detected via _

A

combination of positron emission tomography (PET) and computer-aided tomography (CAT)

Biochemistry (32 decks)

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