L4 biochem Flashcards

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1
Q

is there any digestion protein in mouth ?

A

no

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2
Q

what are the substances that important for digestion of protein inside the stomach ?

A

-gastric HCl
-pepsin
-rennin

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3
Q

describe functions of gastric HCl ?

A

-it denatures dietary protein (unfolding)/ exposure of peptide bond to digestive enzyme
-activation of pepsinogen to pepsin

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4
Q

pepsin will act at what pH

A

2

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5
Q

What substance which stimulate pepsin activation from pepsinogen

A

-HCl
-auto activation by pepsin

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6
Q

rennin act at what pH

A

4-5

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7
Q

it is endopeptidase
it is only secreted in infant and and child age

A

rennin

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8
Q

what are the function of rennin

A

-digest milk protein in infant
-make milk clot to prevent rapid passage so that allow better digestion and absorption

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9
Q

what happened during digestion

A

large polypeptides from stomach will be further cleaved into oligopeptides and amino acid by pancreatic protease

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10
Q

release of pancreatic protease is mediated by

A

cholecystokinin
secretin

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11
Q

list 2 types of pancreatic protease

A

-endopeptidase
-exopeptidase :
1. carboxypeptidase
2. aminopeptidase

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12
Q

list 5 types of pancreatic proteases

A
  1. trypsin
  2. chemotrypsin
  3. elastase
  4. collagenase
  5. carboxypeptidase
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13
Q

it is the only pancreatic protease which exopeptidase

A

carboxypeptidase

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14
Q

trypsin is activated by

A
  • intestinal enteropeptidase (enterokinase)
  • auto activation by trypsin
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15
Q

trypsin act at what pH

A

8

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16
Q

what are the function of trypsin

A

-acts on peptide bond formed by basic amino acid into polypeptide
-activation of other enzymes as chymotrypsin and carboxypeptidase

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17
Q

enumerate enzymes which activated by trypsin

A

chemotrypsinogen
pro-elastase
pro-collagenase
pro-carboxypeptidase

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18
Q

mention 2 or 3 intestinal enzymes

A

aminopeptidase
tripeptidase
dipeptidase

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19
Q

what are the end product of protein digestion

A

mixture of amino acid, tripeptides and dipeptides

20
Q

describe 3 hormones that help protein digestion

A

gastrin hormone
cholecystokinin
secretin

21
Q

what is action of gastrin hormone

A

secretion of pepsinogen and intrinsic factor

22
Q

what is the function of cholecystokinin

A

secretion of pancreatic enzymes

23
Q

what is the action of secretin

A

secretion of pancreatic enzymes and bicarbonate

24
Q

they are secreted by duodenum and jejunum

A

cholecystokinin
secretin

25
Q

what are the abnormalities in protein digestion

A
  1. deficiency in pancreatic secretion
  2. in acute pancreatitis
26
Q

where is the site of protein absorption

A

jejunum and ileum

27
Q

mention 2 mechanism of protein

A

sodium dependent active transport
glutathione transport system

28
Q

describe sodium dependent active transport

A

-it is main mechanism for AA absorption
-AA has specific carrier, each carrier has specific site for AA and other site for sodium
-it requires ATP
-after absorption AA go to portal circulation by facililated diffusion and sodium detached by exchange with potassium via NaK pump

29
Q

list 5 types of sodium dependent carrier protein

A

-carrier for small neutral AA
-carrier for large neutral AA
-carrier for basic AA
-carrier for acidic AA
-carrier for imino acid

30
Q

glutathione transport system is used for transportation of

A

neutral amino acid

31
Q

what are the elements needed for glutathione transport system

A

glutathione
gamma glutamyl transferase
ATP

32
Q

explain steps of glutathione transport system (regenerate glutathione)

A
  1. glutathione binds to AA form gamma glutamyl-AA and cysteinyl-glycine (by gamma-glutamyl transpeptidase with the presence of Na)
  2. gamma glutamyl AA is cleaved into free AA and 5-oxoproline
  3. 5-oxoproline-> glutamate (by 5-oxoprolinase and ATP)
  4. cysteinyl-glycine is cleaved into cysteine and glycine
  5. glutamate + cysteine -> gamma glutamyl cysteine
  6. gamma glutamyl cysteine + glycine-> glutathione
33
Q

glutathione transport system requires how many ATP

A

3 ATP

34
Q

what are the functions of glutathione transport system

A

-transport of AA
-synthesis of glutathione

35
Q

what are the clinical importance of gamma glutamyl transferase (GGT)

A

provide sensitive index of liver abnormality because it is microsomal enzyme from hepatobiliary system

36
Q

GGT increase in blood in case of

A

cholestases
chronic alcoholism

37
Q

list absorption of intact proteins that dont need digestion

A

-Ig of colostrum (provide passive immunity to the infant)
-vaccine (undigested polypeptide)

38
Q

enumerate disorder associated with defects in AA transport

A
  1. hartnup disease
  2. cystinuria
  3. celiac disease
39
Q

it is inherited autosomal recessive disease.
due to deficiency of transport system of large neutral AA like tryptophan.

A

hartnup disease

40
Q

what are the clinical manifestation and diagnosis of hartnup disease

A

-dermatitis (pellagra like skin rash due to deficiency of niacin)
-cerebral ataxia
-mental retardation
dignosis:
- aminoaciduria
-increased excretion of indol (tryptophan) in urine

41
Q

it is most common inherited genetic disorder.
defect in the carrier system of COAL AA

A

cystinuria

42
Q

what are the COAL amino acids

A

cystine
ornithine
arginine
lysine

43
Q

enumerate clinical manifestation and diagnosis of cystinuria

A

-formation of calculi in urinary tract
-obstruction
-infection
-renal insufficiency
diagnosis:
amino acid appear in urine

44
Q

what is treatment of cystinuria

A

oral hydration

45
Q

what is cause of celiac disease

A

sensitivity to gluten protein in wheat and barley lead to immune mediated damage the wall of small intestine (sympstoms : malabsorption)