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Biochem > Biochem Exam 1: Set 4 (Glycolysis, Fat Metabolism) > Flashcards

Biochem Exam 1: Set 4 (Glycolysis, Fat Metabolism) Flashcards

1
Q

Which cells can not generate ATP from glycolysis?

A

they all can

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2
Q

What proteins are responsible for glucose transport into cardiocytes (heart)?

A

GLUT1 (10%) and GLUT4 (90%)

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3
Q

What are the 4 possible fates of G-6-P?

A

Storage as glycogen, pentose phosphate pathway, stored in liver to regulate blood glucose, glycolysis

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4
Q

Why do red blood cells possess hexokinase instead of glucokinase?

A

hexokinase has a much lower Km, ensuring RBC’s will utilize glucose for ATP synthesis before the liver

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5
Q

What is the first committed step of glycolysis?

A

Conversion of F-6-P to F-1,6-BP via phosphrofructokinase 1

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6
Q

How does the cell trap glucose in the cytoplasm?

A

addition of charged phosphate (glucose–>G-6-P) via hexo/glucokinase prevents diffusion out of the membrane

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7
Q

What are the intermediates of glycolysis?

A 
glucose
G-6-P
F-6-P
F-1,6-BP
G-3-P (and DAP)
1,3-BPG
3-PG
2-PG
PEP
Pyruvate
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8
Q

What are the enzymes of glycolysis?

A 
gluco/hexokinase
phosphoglucose isomerase
phosphofructokinase 
fructosebisphosphate aldolase
(triose phosphate isomerase)
glyceraldehyde-3-phosphate dehydrogenase
phosphoglycerate kinase
phosphoglycerate mutase
enolase
pyruvate kinase
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9
Q

Where does glycolysis occur?

A

in the cytoplasm

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10
Q

How many ATP is obtained per NADH via the glycerol 3-phosphate shuttle?

A

1.5

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11
Q

How many ATP is obtained per NADH via the malate-asparate shuttle?

A

2.5

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12
Q

What are the regulators of glycolysis?

A 
\+AMP
\+ADP
\+fructose-2,6-BP
-ATP
-acidosis
-citrate
-NADH
-acetyl CoA
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13
Q

How does F-1-P inhibit glucokinase activity?

A

F-1-P interferes with the interaction between GK and its regulatory protein (RP), allowing GK to diffuse outside of the nucleus

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14
Q

How does the interaction between epinephrine and PFK2 differ between the heart and the liver?

A

Heart PFK2 isozyme is activated by phosphorylation and induces glycolysis, and liver PFK2 isozyme is inhibited by phosphorylation

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15
Q

What compounds activate glucokinase activity?

A

glucose and F-6-P

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16
Q

How much acetyl-CoA would be obtained from complete beta oxidation of palmitate?

A

palmitate= 16:0 so 8 acetyl-CoA

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17
Q

How many carbons make up a short, medium, and long fatty acid chain?

A

short: 4
medium: 6-12
long: 12-20

18
Q

What percentage of naturally occurring unsaturated fatty acids contain trans double bonds?

A

0%

chemical hydrogenation of polyunsaturated vegetable oil produces trans bonds

19
Q

What drives the reaction of fatty acyl CoA synthetase?

A

removal of pyrophosphate product (hydrolysis to 2Pi)

20
Q

Which phosphate of ATP does the fatty acid attach in the first step of fatty acyl CoA synthesis?

A

the first phosphate

21
Q

What is the net equation for the reaction catalyzed by fatty acyl CoA synthetase?

A

fatty acid + ATP + CoA –> 2Pi + AMP + fatty acyl CoA

22
Q

Where in the cell are the acyl-CoA synthetase isozymes located that are specific for short, medium, long and very long fatty acid chains?

A

Short- cytosol or on the mitochondrial membrane
Medium- transported into mitochondria and activated in the matrix
Long- ER, outer mitochondrial membrane, or peroxisomal membranes
Very Long- Only in peroxisomes

23
Q

What molecule is required for fatty acyl CoA transport into the mitochondria

A

carnitine (via carnitine palmitoyl transferases I and II)

24
Q

Describe the general steps in B-oxidation of saturated fatty acyl-CoA’s

A
  1. trans double bond formed between alpha and beta carbon
  2. double bond reacts with water to form alcohol on beta carbon
  3. alcohol is oxidized to a ketone
  4. CoA-SH attacks beta ketone releasing acetyl-CoA
25
Q

List the enzymes involved in B-oxidation

A

acyl-CoA dehydrogenase, enoyl-CoA hydratase, 3-L-hydroxyacyl-CoA dehydrogenase, B-ketoacyl-CoA thiolase

26
Q

What is the major dietary source of odd number fatty acids?

A

plants

27
Q

What additional product will be produced in the complete B-oxidation of an odd numbered fatty acid

A

propionyl-CoA

28
Q

What is propionyl-CoA used for?

A

converted to succinyl-CoA (intermediate in TCA) via propionyl-CoA carboxylase which requires Biotin

29
Q

What general enzymes are involved in B-oxidation of unsaturated fatty acids?

A
  • trans alkenes- B-oxidation proceeds normally,
  • isomerases convert cis alkenes to trans alkenes
  • adjacent double bonds- dehydrogenases use NAD+ to remove the double bond
30
Q

What harmful byproduct is produced in B-oxidation of very long chain fatty acids?

A

Occurs only in peroxisomes, produces hydrogen peroxide which can then become a reactive oxygen species

31
Q

When and where does alpha-oxidation occur?

A

in peroxisomes, and is used for oxidation of branched fatty acids (CO2 is released)

32
Q

Where does omega-oxidation occur?

A

in the endoplasmic reticulum

33
Q

What product of omega-oxidation is involved with feedback inhibition?

A

NONE OF THEM- omega-oxidation is not feedback regulated

34
Q

What is the product of omega-oxidation?

A

dicarboxylic acids

35
Q

What is the net reaction of B-oxidation of stearic acid?

A

C18-CoA + 8 CoASH + 8NAD+ + 8 FAD + 8 H2O –>

9 acetyl-CoA + 8 NADH + 8 H+ + 8 FADH2

36
Q

How many ATP’s are synthesized from the complete metabolism of an 18-C fatty acid?

A

120

37
Q

What regulates B-oxidation?

A 
\+insulin
\+ADP
-ATP
-Malonyl CoA
-NADH (FADH2)
-glucagon
38
Q

What are the three major ketone bodies?

A

acetoacetate, acetone, B-hydroxy-butyrate

39
Q

Where are ketone bodies synthesized?

A

mitochondria in the liver

40
Q

What are ketone bodies made from?

A

acetyl-CoA

41
Q

What is the significance of the enzyme thiophorase being absent in the liver?

A

the liver can make ketone bodies but can’t use them for energy (can’t convert them back to acetyl-CoA)

Biochem (6 decks)

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