Metabolism of macromolecules Flashcards

1
Q

What is the minimal carbon number for carbs

A

3

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2
Q

What is the bond existing in cellulose, glycogen, amylose and amylopectin respectively

A

beta-1,4-glycosidic; alpha-1,4-glycosidic& alpha-1,6-glycosidic; alpha-1,4-glycosidic; alpha-1,4-glycosidic & alpha-1,6-glycosidic

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3
Q

What is the product of Amylose degradation and amylopectin degradation

A

glucose, Maltose and maltotriose; alpha-limiting dextrins (polysachharide then into maltose)

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4
Q

What does the pancreatic and salivary alpha-amylose break

A

Alpha 1,4-glycosidic bonds

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5
Q

Which protein is responsible for the cleavage of most carbs

A

glycosidases

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6
Q

Where are glycosidase located

A

On the brush border of enterocytes

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7
Q

How is glucose uptaken into enterocytes

A

It is uptaken via Na/Glucose transporter 1(SGLT1) against conc gradient by coupling it’s transport to that of Na+, then into blood at basolateral plane via GLUT2

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8
Q

Why fructose uptake is less effective

A

It is because the uptake of fructose is via GLUT5 hence it has no coupling effect of Na+ uptake.

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9
Q

Suggest, what are the 2 phases in Glycolysis

A

Energy investment phase and energy generation phase

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10
Q

Name the intermediates for glycolysis

A

Glucose 6-P, Fructose 6-P, Fructose-1,6-bisP, Pyruvate

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11
Q

Name the antagonist reaction for glycolysis

A

Gluconegenesis

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12
Q

When will anaerobic glycolysis take place

A

When there is insufficient oxygen

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13
Q

How is lactate transported out of the cell

A

Via monocarboxylate transporter (MCT)

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14
Q

How to let lactate re enter respiration

A

Lactate +NAD+ –> Pyruvate + NADH +H+

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15
Q

Is there any carbohydrate that the body cannot synthesis but is necessary

A

No (All can be derived from glycogen)

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16
Q

Name a compound that can be synthesized by glucose that has reducing power

A

NADPH

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17
Q

Name a compound that is synthezied from glucose that involves in RNA production

A

ribose-5-phosphate

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18
Q

What is the test usually done in Hospital that requires appointment to assess body’s response towards Glucose challenge. Suggest the 3 procedures

A

OGTT, Oral Glucose Tolerance Test

  1. Fast for 8h and withdraw blood
  2. Patient drink a glucose solution with glucose amount= (17.4g/kg of body mass)
  3. Withdraw blood In regular interval (30min) until 2h past the drinking of solution
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19
Q

Suggest should be avoided 3 days before OGTT

A

Alcohol, unnecessary drugs, Too much/Too little bed rest, salicylates, diuretics, anticonvulsants, fever (??)

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20
Q

Suggest how BGL can be determined by blood sample

A
  1. Glucose is oxidized by glucose oxidase to form gluconic acid and Hydrogen peroxide
  2. Hydrogen peroxide is split into water and oxygen by peroxidase
  3. Oxygen oxidizes o-dianisidine from colourless to brown
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21
Q

Suggest the term that describes being freezed and dried

A

lyophilized

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22
Q

What are the 7 types of fat

A

Bile salt,
Eicosanoids (Arachidonic Acid derivates, prostaglandins, thromboxanes, leukotrienes, lipoxins)
Steroids
Triacylglycerol
Phospholipids
Vitamins (ADEK)
Cholesterol

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23
Q

Why cis unsaturated fatty acids are good

A

They have C=C ,which can make it kink

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24
Q

Name the first site of fat digestion, the enzyme and the product

A

Stomach, Lingual Lipase and Human Gastric Lipase, diacylglycerol

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25
Q

Name the 2 hormone that involves in lipid digestion and their function

A

Cholecytostokinin: stimulate the gall bladder and pancreas to squeeze to release bile and pancreatic juice respectively

Secretin stimulates to release of NaHCO3 by pancreas and inhibits the secretion of gastric juice to raise intestinal pH

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26
Q

What is the main site of lipid digestion and the names

A

intestine. Colipase, pancreatic lipase, etc

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27
Q

What is the product of TAG hydrolysis

A

2FFA (Free Fatty acid) and 2-monoacylglycerol

28
Q

What are the differences in pathway between short/medium FFA and long ones

A

Short/Medium
1. Forming michelle/directly pass the water layer overlying microvilli
2. Enter blood directly and bind to albumin

Long
1. Form michelle to pass the water film
2. Enter enterocytes to be packed into TAG, bind to chylemicron to reach lacteal, entering the thoracic duct, entering lymphatic system and return to blood at the left subclavian vein

29
Q

How can lipid exist in lymph

A

In chylemicrons (a lipoprotein),

30
Q

How can lipid exist in blood

A

Binding to albumin

31
Q

What is the compostional difference between michelle and lipoprotein

A

Michelle is usually made of phospholipid forming a sphere, or a bile acid at centre in intestinal lumen.

Lipoprotein is the combination of protein (apolipoprotein) and lipid, with a hydrophobic cholesterol +triacylglycerol core and a outershell formed by phospholipid and non-esterified cholesterol

32
Q

What is the structural and functional difference between the 2 types of adipose tissue

A

Brown adipose tissue is to generate heat without shivering, hence contains a lot of mitochondrion that contributes to it’s brown colour to release heat by respiration

White adipose tissue is for storing TAG inside the cell

33
Q

What is the minor storage site for TAG

A

Liver and skeletal muscles

34
Q

What does Lipoprotein Lipase do

A

It hydrolyses TAG in chylemicron and IDL (derives from VLDL)

35
Q

What is the fate of the FFA produced from above reaction

A

it becomes Fatty Acyl Co-A (FA Co-A)

36
Q

What is the action of insulin on adipocytes

A

It stimulate the expression of GLUT 4 on the cell membrane to uptake more glucose

37
Q

What is the fate of glucose in adipocyte

A

It becomes dihydroxylacetone glucose (DHAP) then glycerol 3-phosphate (G3P)

38
Q

Write the equation for formation of TAG in the adipose tissue

A

FA Co-A + G3P –> TAG

39
Q

Under what circumstances will TAG be used for lipolysis. What are the procedures

A

Under high glucagon or low insulin. It activates hormone sensitive lipase to cleave TAG

40
Q

What is the fate of FFA and glycerol released in loiver respectively

A

FFA: For beta-oxidation to release a lot of energy and Acetyl Co-A

Glycerol: Used for gluconegenesis to make Glucose

41
Q

WHat is the fate of Acetyl CO-A formed in beta-oxidation

A

To feed into TCA cycle or to make ketone bodies (Under prolonged fasting)

42
Q

Name a compound that is from TCA to make FA

A

Citrate (to Acetyl Co-A then malonyl Co-A via Acetyl Co-A carboxylase then to palmitate (via Fatty Acid Synthase) then FA CoA

43
Q

Where is the conversion take place

A

Cytosol

44
Q

Name the enzyme that cleaves protein in stomach and it’s way to activate

A

Pepsin. It is activated by self-cleaving of pepsinogen under low pH

45
Q

Name 4 zymogens secreted by pancreas

A

trpsinogen, chymotrysinogen, proelastase, procarboxypeptidases

46
Q

What is the difference between endopeptidase and exopeptidase

A

One cut the peptide bond at the middle, one cut at the linear end

47
Q

Name an exopeptidase

A

aminopeptidase (on brush border of enterocytes and inside)

48
Q

What drives the uptake of amino acids,dipeptides and tripeptides

A

By the energy generated by SOdium-Potassium ATPase pump. THen by faciliated transporter to enter blood

49
Q

Explain how polypeptide can enter blood

A

They may slip between cells that lines the gut wall
Pinocytosis

50
Q

Name 1 source of endogenous source of amino acid

A

Protein turnover

51
Q

What is transamination

A

It involves transfering the amino group of an amino acid to a Alpha-keto acid to make it an amino acid

52
Q

How can body utilize amino acid as energy source via transamination

A

By transamination to form alpha KG which is a intermediate of TCA cycle

53
Q

What is the fate of the carbon skeleton of amino acid

A

Into Triacylglycerol (secreted in liver in VLDL) or glucose

54
Q

Name 2 amino acids that has their amino groups removed in deamination to make urea

A

Glutamate, Asparate

55
Q

Name 3 possible fate for the amino group of glutamate

A

Transfered to a keto acid, as ammonia or as ammonium ion

56
Q

What;s the name of hvign too mucb ammonia and ammonium ion respectively. What’s the associated problem

A

Hyperammonia/ Hyperammonemia
It causes neurotoxic conditions to brain cells

57
Q

What is the source for the 2 nitrogen atom of urea from

A

Ammonia and Asparate

58
Q

Name 2 nitrogen carrier in human body

A

Alanine, glutamine

59
Q

Where is alanine formed in the transport of urea. Whats the raw material

A

Skeletal muscles from pyruvate

60
Q

What is the fate of the carbon of alanine

A

It becomes pyruvate then glucose by gluconeogenesis

61
Q

What is the fate of the Nitrogen of Alanine

A

For urea synthesis

62
Q

At liver, what does ketoglutarate form

A

Glutamate

63
Q

What is the involved enzyme

A

alanine aminotransferase

64
Q

What is the fate of Glutamate formed

A

It can be used to form a-ketoglutarate by losing 2 ammonium to form urea forming 1 NADH, or undergoes transamination with oxaloacetate to form a-ketoglutarate and asparate which forms urea

65
Q

How is glutamate made in muscle

A

a-ketoglutarate –> (GDH) Glutamate –> (glutamate syntherase) Glutamine