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GI > Biochemistry > Flashcards

Biochemistry Flashcards

1
Q

What is lipogenesis?

A

The formation of FAs from glucose sources (the opposite cannot happen)

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2
Q

Name the major sites for lipogenesis

A

Lipogenesis happens in a lot of cells (liver, kidneys, mammary glands, brain and adipose tissue) - only converted into triglycerides in liver and adipose tissue

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3
Q

What are the actions of insulin and glucagon on lipogenesis?

A 
Insulin = increases lipogenesis
Glucagon = inhibits lipogenesis
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4
Q

In normal physiology what is starch broken down into?

A

Acteyl-CoA

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5
Q

What is the function of citrate in lipogenesis?

A

To transport acteyl groups into cytoplasm

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6
Q

Explain the function of ACP

A

ACP is an acyl-carrier protein which binds to a starter chain to begin a FA

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7
Q

State and explain the 4 steps of FA synthesis

A

Condensation (release H20)
Reduction (gain e - more stable)
Dehydration (release H20)
Reduction and release

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8
Q

Which molecules acts as an electron donor in lipogenesis?

A

NADPH

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9
Q

What 2 molecules are used to carry C atoms in lipogenesis?

A

Malonyl-CoA

Acetyl-CoA

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10
Q

What 2 molecules are joined together to form triglycerides?

A

G-3-P (glycerol-3-phosphate)

+ 3x FAs

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11
Q

What other similar products are produced in the liver?

A

Cholesterol
Phospholipids
Lipoproteins

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12
Q

What are the 2 parts of glycogen?

A

Glycogenin and multiple glucose molecules

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13
Q

Name the bonds found in glycogen molecules

A

alpha 1-4 glycosidic - straight

alpha 1-6 glycosidic = branches

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14
Q

Where in the body are the largest quantitites of glycogen found?

A

Liver - to maintain blood sugars

Muscle - provide energy during exercise

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15
Q

What is the name of the basic process that produces glycogen from a starter molecule and monomer units?

A

Glyogenesis

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16
Q

UDP-glucose serves what role in producing glycogen?

A

Acts as an activated form of glucose that gets attached to glycogen chains

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17
Q

Glycogen synthase and transglycosylase differ largely in 1 way; what is it?

A

Glycogen synthase attaches straight chains

Transglycosylase attaches branches

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18
Q

What is the rate limiting enzyme of glycogen production?

A

Hexokinase

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19
Q

Gluconeogenesis can produce glucose from what 3 major classes of molecule?

A

Amino acids
Lactate
Glycerol

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20
Q

What is the cori cycle?

A

The reverse of anaerobic respiration

Turns lactate -> glucose

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21
Q

Where does the cori cycle take place?

A

Liver mitochondria

22
Q

What is the “energy cost” of the cori cycle?

A

Cori cycle requires more energy than anaerobic respiration releases - not energy efficent

23
Q

What is the name of the process that breaks glycogen to monomer subunits?

A

Glycolysis

24
Q

What 2 fates befall the monomer subunits of glycogen break down?

A

Muscles -Further glycolysis

Liver - Converted into glucose

25
Q

What transport molecule is involved in the fate of monomers in the liver?

A

GLUT2

26
Q

What are the 3 types of lipid, and how do they differ?

A

Simple
Compound
Steroids
Increasingly complex with added groups

27
Q

What are lipids soluble in?

A

Non-polar compounds

like dissolve like

28
Q

What are the 2 components in triglycerides?

A

Glycerol (G-3-P) and 3 FAs

29
Q

Where are triglycerides the major energy storage?

A

Adipose tissue

30
Q

Where is acyl CoA transported into?

A

Cytoplasm

31
Q

Draw the mechanism of acyl CoA transport

A

Sketch of carnitine shuffle

32
Q

How is acyl carnitine formed?

A

acyl-CoA
+
carnitine

33
Q

List the products of B-oxidation per cycle

A 
FADH 
Acetyl-CoA
Acyl-CoA
NADH + H
(FAAN)

PLUS
1x acetyl-CoA

34
Q

A 14C fatty acid would produce what after B-oxidation

A 
C/2 - 1 = 7 - 1 = 6
6x FADH
7x Acteyl-CoA
6x Acyl-CoA
6x NADH + H
35
Q

Where does B-oxidation occur?

A

Mitochondria

36
Q

Are ketones physiologically present?

A

Yes - in small amounts

37
Q

Which states are ketones dangerous?

A

Starvation and diabetes - oxcalatone is used up in gluconeogenesis so can’t break down acteyl-CoA

38
Q

How do ketones cause damage?

A

They are slightly acidic so when in high amounts causes metabolic acidosis -> organ damage

39
Q

Which body locations are ketones used ?

A

Kidneys and heart

40
Q

What atom/molecule do AA contain that mean they need to be excreted?

A

Nitrogen

41
Q

The dangerous components of AA are excreted as which molecules? Which is most common?

A

Urea, uric acid, creatinine, NH4 (ammonium)

Urea = most common

42
Q

What enzymes act on proteins to form AA?

A

Proteolytic

43
Q

Where are AA absorbed?

A

Intestinal cells - small bowel

44
Q

What is transanimation?

A

Moving amino group from AA to alpha keto acid

45
Q

Where does transanimation occur?

A

In all body cells

46
Q

What 2 molecules are used to transport molecule products of transanimation to the liver?

A

Glutamine and alanine

gluty alan

47
Q

What is deanimation?

A

Conversion of amino groups to free ammonium ions in liver

48
Q

Where is urea synthesised?

A

Mitochondrial matrix

49
Q

What is the purpose of synthesising urea? (not to get rid of urea)

A

Less soluble than other forms of nitrogen compunds so less water is needed to be excreted alongside urea

50
Q

What is the fate of carbon skeletons left after AA metabolism?

A

Converted to glucose

Oxidised in TCA cycle

GI (26 decks)

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