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Word Association for Biochem test 1 > Important Enzymes and Intermediates > Flashcards

Important Enzymes and Intermediates Flashcards

1
Q

Hexokinase

A 
Glucose to Glucose 6-P in Glycolysis 
Slow 
Low Vmax and Km
In all cells 
Uses ATP
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2
Q

Glucokinase

A 
Glucose to Glucose 6-P in Glycolysis 
Fast
Only in liver and kidney 
High Vmax and Km
Uses ATP
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3
Q

Glut 4 tansporter

A

Insulin Sensitive

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4
Q

Glut 2 Transporter

A

NON-insulin sensitive
Only in brain, liver and pancreas
(Brain and liver need to be able to take up glucose all of the time. And the pancreas needs to be able to “sense” glucose even without insulin so it does its freaking job)

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5
Q

Phosphofructokinase-1

A

Enzyme for Fructose 6-p to Fructose 1,6 PB
RATE LIMITING STEP FOR GLYCOLYSIS
Consumes ATP
Allosterically regulated
Ex: High glucose/High insulin&raquo_space; decreased cAMP&raquo_space; decreased protein kinase A&raquo_space; activated PFK2&raquo_space; increases Fructose 2,6 PB&raquo_space; stimulates PFK1!!!!

PFK1 is downregulated by ATP and citrate (both from TCA cycle) and upregulated by AMP, F2,6BP

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6
Q

Pyruvate kinase

A

Enzyme for PEP to Pyruvate.

Creates 2 ATP (4 per glucose molecule)

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7
Q

Lactate dehydrogenase

A

Enzyme for Pyruvate to Lactate.

Uses NADH to create NAD+, which can be used in glycolysis

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8
Q

Pyruvate dyhydrogenase

A

Enzyme for Pyruvate to Acetyl CoA

Relies on Thiamine as a cofactor (people who only consume alcohol don’t have this enzyme – difficulties creating acetyl CoA and all the stuff that follows)

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9
Q

What are the steps you need to know in Glycolysis (intermediates)?

A

Glucose&raquo_space; Glucose6-P&raquo_space; Fructose 6-P&raquo_space; Fructose 1,6-P&raquo_space;&raquo_space; PEP&raquo_space; Pyruvate&raquo_space; Acetyl CoA OR Lactate

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10
Q

Glucagon

A

Think of it like “hungry insulin”… released during fasting.
PHOSPHORYLATES
Promotes gluconeogenesis

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11
Q

Insulin

A

Released in presence of glucose (fed state)
Promotes glycolysis
DE-phosphorylates

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12
Q

What are the steps (intermediates) of the TCA cycle

A

Pyruvate&raquo_space; Acetyl CoA&raquo_space; Citrate&raquo_space; alpha ketogutarate&raquo_space; Succinate&raquo_space; Fumarate&raquo_space; L-malate&raquo_space; Oxaloacetate

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13
Q

Products of TCA cycle

A

NADH
FADH
GTP
CO2

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14
Q

Where do amino acids enter the TCA cycle?

A

alpha-ketoglutarate

Succinate

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15
Q

Pyruvate carboxylase

A

Enzyme for Pyruvate to Oxaloacetate in gluconeogenesis

Uses 2 ATP

Activated by high Acetyl CoA

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16
Q

PEPCK

A

Enzyme for Oxaloacetate to PEP in gluconeogenesis

Uses 2 GTP

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17
Q

Fructose 1,6 bisphosphatase

A

Enzyme for Fructose 1,6 BP to Fructose 6-P in gluconeogenesis

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18
Q

Glucose 6 phosphatase

A

Enzyme for Glucose 6-P to Glucose in gluconegenesis

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19
Q

What are the main steps (intermediates) in gluconeogenesis?

A

Pyruvate&raquo_space; Oxaloacetate&raquo_space; PEP&raquo_space;&raquo_space;Fructose 1,6PB&raquo_space; Fructose 6P&raquo_space; Glucose 6 P&raquo_space; Glucose

20
Q

Precursors for Gluconeogenesis

A

Lactate: generated in skeletal muscle. Lactate can be converted to pyruvate

Amino Acids: provide carbon skeletons to the TCA, which results in the production of glucose via oxaloacetate

Glycerol: Released during hydrolysis of trigylcerides in adipose. Bypasses PEP and continues from there. Enters cycle as Glyceraldehyde 3-P

21
Q

Where in the cell, and in which organs, does gluconeogenesis take place?

A

Cytosol of liver (and kidneys)

22
Q

Glycogen

A

A storage form of glucose, mainly in muscle and liver

Glycogenesis (Synthesis): Occurs in well-fed state. Key enzyme in glycogen synthase. Branching enzyme. Insulin dephosporylates glycogen synthase (activating it) which inhibits glycogen breakdown.

Glycogenolysis (Breakdown): Occurs in fasting state. Key enzyme is glycogen phosphorylase. De-branching enzyme. Activated by glucagon in liver or epinephrine. Phosphorylates glycogen phosphorylase.

23
Q

Fatty acid synthase

A

Enzyme in fatty acid synthesis that converts Malonyl CoA to Fatty acid

24
Q

Acetyl CoA carboxylase

A

Enzyme in fatty acid synthesis that converts Acetyl CoA to Malonyl CoA. Is the RATE LIMITING STEP

25
Q

Malonyl CoA

A

What finally “becomes” fatty acid during synthesis. Is and INHIBITOR of the carnitine shuttle, used in fatty acid breakdown (B-oxidation)

26
Q

Citrate Shuttle

A

In the mitochondrial membrane
Fatty acid synthesis
Acetyle CoA in the mitochondria to OUT into the cytoplasm

27
Q

Basic steps of fatty acid synthesis

A

Acetyle CoA (in mitochondria)&raquo_space; Citrate Shuttle&raquo_space; Acetyl CoA in cytoplasm&raquo_space; Malonyl CoA&raquo_space; Fatty acid

28
Q

Fatty acid elongation and desaturation

A

Elongation takes place in the ER and the mitochondria

Desaturation takes place in the ER

29
Q

Fatty acid CoA synthase

A

Enzyme that converts Fatty Acid CoA to Aycl CoA in Fatty Acid breakdown (beta oxidation)

30
Q

Acyl CoA Dehydrogenase

A

Enzymes that converts Acyl CoA to Acetyl CoA in fatty acid breakdown (beta oxidation)

31
Q

Basic steps in Fatty Acid breakdown (Beta oxidation)

A

Fatty acid in cytoplasm&raquo_space; Acyl CoA&raquo_space; Carnitine Shuttle&raquo_space; Acyl CoA in mitochondria&raquo_space; Acetyl CoA

32
Q

What are ketone bodies and how do they get into your blood?

A

In Diabetes (hyperglycemia) all of the oxaloactetate is being used in gluconeogensis (hence the hyperglycemia). With OAA to help run the TCA cycle, Acetyl CoA will be used to make ketone bodies to help “feed” the muscles and brain

Also, if you are reallllly hungry, your liver will start breaking down the fatty acids. During this time, your body is probably also still trying to do gluconeogenesis. Regardless, ketones are made via fatty acid breakdown in order to got the brain and muscles for fuel, where ketones will be reconfigured into the much-desired Acetyl CoA

33
Q

HMG CoA reductase

A

RATE LIMITING STEP in cholesterol synthesis

Stimulated by insulin

34
Q

HMG CoA

A

Cholesterol synthesis

35
Q

Mevalonate

A

Cholesterol synthesis

36
Q

Squalene

A

Cholesterol synthesis

37
Q

What is consumed in Cholesterol synthesis

A

NADPH&raquo_space; NAD

38
Q

Lipoproteins

A

Apolipoprotein + (Cholesteol or Triglycerides or Phospolipids)

VLDL, IDL, LDL, HDL

39
Q

Pancreatic Lipase

A

In intestine, degrades triglycerides into Free Fatty Acids

40
Q

Lipoprotein Lipase (LPL)

A

Found in vascular epithelium in adipose and muscle cells. Tryglycerides&raquo_space;> free fatty acids

41
Q

Hepatic Triglyceride Lipase

A

Degrades IDLs into LSL

42
Q

Hormone Sensitive Lipase

A

Intracellular; Degrades TGs in adipose cells

43
Q

Apolipoprotein E

A

Mediates remant uptake in liver

Chylomicron, Chylomicron remnant, VLDL, HDL

44
Q

What amino acid can modestly increase dTMP levels in the setting of folate deficiency

A

Thymidine

45
Q

De novo synthesis of pyrimidines requires what amino acid(s)?

A

Aspartate

46
Q

De novo synthesis of purines requires what amino acid(s)?

A

Aspartate, glycine, glutamine,

And THF

Word Association for Biochem test 1 (3 decks)

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