Week 15: lipids and amino acids, integration of metabolism Flashcards

1
Q

Where is the site major of amino acid degradation?

A

LIVER

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2
Q

what happens to amino acids that are not used?

A

degraded

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3
Q

What breaks down amino acids in the stomach and intestine for adsorption?

A

proteolytic enzymes

to di and tri peptides

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4
Q

What absorbs amino acids?

A

intestinal cells and released into the blood for absorption by other tissues.

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5
Q

Is there a storage form of amino acids?

A

no

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6
Q

What is another way that the body generates free amino acids that it needs to deal with?

A

protein turnover

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7
Q

What is protein turnover?

A

forms a very important part of the intercellular quality control process

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8
Q

What is protein turnover important for?

A

rapid changed, damaged proteins have to be removed

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9
Q

Amino acids contains a amide side chain but where else can N be found?

A

some amino acids also contain nitrogen in the side chain

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10
Q

What is produced when amino acids are broken down?

A

NH3 (ammonia) & ammonium NH4+

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11
Q

Is NH4+ toxic?

A

YES

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12
Q

What can happen if there is a build up of Nitrogen compounds?

A

Leads to severe problems

needs a safe way of exerting excess Nitrogen

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13
Q

What are you left with after removal of alpha-amino group (N)?

A

carbon skeleton

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14
Q

What is the remaining carbon skeleton converted to after removal of alpha-amino group?

A

major metabolites intermediates

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15
Q

What can the major metabolic intermediates then be converted to?

A

converted to glucose or oxidised in the TCA cycle

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16
Q

What are the 2 categories of amino acids?

A

ketogenic AA

Glucogenic AA

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17
Q

What can ketogenic AA be degraded to?

A
  • Degraded to acetyl-CoA or acetoacetyl-CoA

- Give rise to ketone bodies or fatty acids

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18
Q

What can glucogenic AA be degraded to?

A
  • Degraded to pyruvate or TCA cycle intermediates

- Can be converted into phosphoenolpyruvate and then into glucose

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19
Q

What 3 disorders that effects amino acid degredation?

A

Alcaptonuria
Maple syrup Urine disease
Phenylketonuria

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20
Q

What type of amino acids are phenylalanine and tyrosine?

A

ketogenic and glucogenic AA

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21
Q

What enzymes are degraded and blocked in maple syrup urine disease?

A

degradation of valine, isoleucine

blockage of leucine

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22
Q

What enzymes are accumulates in Phenylketonuria?

A

phenylalanine in body fluids

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23
Q

What enzymes are degraded and blocked in Alcaptonuria?

A

phenylalanine degraded

tyrosine blocked

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24
Q

What is the prevention for maple syrup urine disease?

A

prevented by appropriate diet

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25
Q

What is the therapy for phenylketonuria?

A

Low phenylalanine diet

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26
Q

What happens when you have increased fat intake without appropriate energy expenditure?

A

increased number of adipocytes
more fat in adipocytes
obesity

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27
Q

How do you control energy balance in the body?

A
  • Genetically linked factors (protein messengers regulating appetite
  • Environmental factors (food abundance, fashionable foods)
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28
Q

What are medical complications of being obese?

A
diabetes type 2
coronary heart disease
hypertension
stroke
arthritis
gall bladder disease
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29
Q

What is fat required for?

A
  • As an energy source

- For essential fatty acids (some polyunsaturated fatty acids can not be made by the body)

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30
Q

What can a deficiency in essential fatty acids lead to?

A

membrane disorders, increased skin permeability, mitochondrial damage

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31
Q

What are fat-soluble. vitamins stored in fat?

A

A, D, E , K

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32
Q

What can happen id you don’t have enough fat to store vitamins?

A

a secondary deficiencies can occur

efficiency in the vitamins

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33
Q

What is the building block of steroids?

A

cholesterol

34
Q

Does cholesterol contain fatty acids?

A

Not usually

occur in natural fats

35
Q

What is the chemical structure of cholesterol?

A

rigid structure, multiple rings, in cell membranes

changes membrane properties

36
Q

What hormones is cholesterol an important pre-cursor for?

A

adrenocortical and sex hormones (progesterone, testosterone & oestrogen)

37
Q

What is another form of fats that are needed to try and digest a meal?

A

Triglycerides

triacylglycerols

38
Q

What is the main energy storage form in adipose tissue?

A

triglycerides

39
Q

Why are triglycerides used as storage in the adipose tissue?

A

-Very compact
the acyl groups mean they are hydrophobic and don’t require water so become very compact
leads to a high energy yield per gram

40
Q

What is the features of a fatty acid structure?

A

mainly straight chains
aliphatic (no rings)
usually an even number of c atoms (2-120 or more)
can be… saturated, unsaturated, polyunsaturated

41
Q

Do fatty acids usually have odd branched chains?

A

NO, usually even no. C atoms & no branches

42
Q

What configuration are double bonds normally in?

A

cis/trans

43
Q

What is the main products of fat digestion?

A

glycerol
fatty acids
monoglycerides (1 fatty acid + 1 glycerol)

44
Q

Where is glycerol readily absorbed into?

A

intestinal epithelial cells

45
Q

Where are fatty acids and monoglycerides absorbed into?

A

mucosal cells of intestine

46
Q

Where do short and medium length fatty acids enter after being absorbed into mucosal cells?

A

enter portal blood

47
Q

Where do long chain fatty acids and monoglycerides enter after being absorbed into mucosal cells?

A

Are re-synthesised to triacyglycerides in the mucosal cell

48
Q

What are the monoglycerides and fatty acids coated with to form?

A

layer of protein, phospholipid, cholesterol to form

Chylomicrons (now can facilitate transport)

49
Q

Where does the chylomicrons enter after synthesis

A

the lymph system then blood stream

50
Q

What happens to chylomicrons when it reaches muscle and adipose tissue?

A
  • Attacked and cleaved by lipoprotein lipases

- Release free fatty acids

51
Q

What are the free fatty acids re-synthesised to in adipose tissue, for storage?

A

triacyglycerols

52
Q

What does the stored triacyglycerols get oxidised to to provide?

A

ENERGY

outcome depends on energy needs

53
Q

What is lipopolysis?

A

breakdown of lipids

54
Q

Can fatty acids be straight oxidised to generate energy?

A

NO, have to be converted to CoA derivatives.

55
Q

What is CoA role on fatty acid?

A

Forms as an activator, makes chains more active

56
Q

Does the fatty acid+ CoA–> acyl CoA require energy?

A

YES 2 ATP

57
Q

What does fatty acid bind to and what does it produce in order to be oxidised?

A

fatty acid+ CoA –> acyl-CoA

58
Q

Where does the fatty acid pick up the CoA?

A

cytoplasm
must go to the mitochondria via carrier mechanism for it to be oxidised
need to get to the matrix

59
Q

In the cytoplasm, fatty acids are transferred from acyl-CoA to what?

A

carnitine

60
Q

When Acyl-CoA transfers its fatty acids to carnitine, what does carnitine become?

A

Acyl-carnitine and enters the matrix

61
Q

When the acyl-carantine enters the mitochondrial matrix what can now occur?

A

beta oxidation

62
Q

What is produced in the the beta-oxidation (cycle)?

A

1 acetyl-CoA
1FADH2
1NADH+ H+
1 fatty acyl-CoA, shortened by 2 carbon atoms

63
Q

When does a free (second) CoA enter the beta oxidation (cycle)?

A

The last step added to 3-ketoacyl CoA

64
Q

whhat are the 2 end products of the beta oxidation cycle?

A

acyl coA & acetyl CoA

65
Q

What is the fate of acetyl-coA after beta oxidation?

A

TCA cycle

66
Q

What produces more ATP, fatty acids or glucose?

A

FATTY ACIDS! 120ATP

67
Q

Give and example of what a triglyceride is?

A

e.g 3 stearic acids bonded to a glycerol

68
Q

What is glycerol?

A

the connector of the 3 fatty acids

69
Q

How do you breakdown glycerol?

A

glycerol kinase activates the glycerol-3-phosphate

70
Q

Where is the glycerol kinase present?

A

liver and kidney but not adipose tissue, skeletal and heart muscle

71
Q

What is glycerol-3-phosphate dehydrogenated to?

A

dihydroxyacetone phosphate

DHAP

72
Q

What can the DHAP be converted to (isomerism)?

A

G3P and enter glycolysis

73
Q

What is the process of making fatty acids?

A

lipogenesis

when more energy is taken in than needed

74
Q

Where does lipogenesis occur?

A

liver, kidney, mammary glands, adipose tissue & brain

75
Q

What is the excess of carbohydrate converted to?

A

fatty acids and triglycerides in the liver

76
Q

What are fatty acids then bound to in plasma? (excess of carbohydrate)

A

albumin

77
Q

Where do triglycerides go after carbohydrate is converted to triglycerides?

A

triglycerides formed in the liver are transported to adipose tissue by VLDL for storage

78
Q

What is VLDL?

A

very low density protein

transport triglycerides from liver to adipose tissue

79
Q

Is lipogenesis reductive or an oxidative process?

A

reductive

electrons are required

80
Q

What are the three states of your body in metabolism?

A
  • Post prandial (after food)
  • Post absorptive (after digestion is complete)
  • Fast state (prolonged period of fasting)