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GI First half > Biochem - macronutrients digestions > Flashcards

Biochem - macronutrients digestions Flashcards

1
Q

bonds in proteins? in fats?

A

proteins have peptide bonds

fats have ester bonds

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2
Q

class of enzymes that perform hydrolysis?

A

hydrolases

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3
Q

2 main disaccharides in diet?

A

lactose and sucrose

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4
Q

lactose =

A

galactose + glucose

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5
Q

sucrose =

A

fructose + glucose

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6
Q

starch

A

polysaccharides of glucose; contains amylose and amylopectin

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7
Q

amylose

A

spiral chain, unbranched, alpha 1,4 linked starch components

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8
Q

amylopectin

A

branched polymer of starch with alpha 1,4 chains and 1,6 branches; similar to glycogen

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9
Q

what enzyme works in mouth? what does it do?

A

salivary alpha amylase

cleaves starch by breaking the 1,4 linkages between glucose –> this creates dextrins

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10
Q

dextrins

A

linear and branched oligosaccharides that enter stomach after salivary amylase cleaves starch

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11
Q

digestion that started in the stomach is continued …

A

in the intestines by pancreatic alpha amylase

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12
Q

salivary and pancreatic alpha amylases are…

A

both endo-glucosidases found in the brush border

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13
Q

intestinal absorption : aa vs fats

A

aa absorbed by villi and enter portal vein –> liver

fats dont go through portal vein - they go into lymph as chylomicrons

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14
Q

what neutralizes stomach acid in the small intestine

A

bicarbonate from the pancreas

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15
Q

products of pancreatic alpha amylase on glucose

A

disaccharides maltose and isomaltose, trisaccharides, and small oligosaccharides

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16
Q

what is digested at brush border?

A

sucrose, lactose, and starch products

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17
Q

4 brush border enzymes…

A

hydrolyze di, tri, and oligo saccharides into monosaccharides

glucoamylase
isomaltase
sucrase
lactase

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18
Q

glucoamylase

A

also called alpha glucosidase

cleaves glucose from nonreducing ends of oligosaccharides

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19
Q

sucrase

A

converts sucrose into glucose and fructose

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20
Q

lactase

A

also called beta galactosidase

cleaves lactose into galactose and glucose

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21
Q

transport in intestines

A

glucose and Na+ are transported by secondary active transport

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22
Q

B-galactosidase deficiency

A

lactase deficiency
lactose cannot be digested and is oxidized instead by gut bacteria which produces gas and causes bloating and watery diarrhea due to increased osmotic pressure
-common in asians

23
Q

dietary fiber

A

carbs that cannot be digested

=cellulose, carragennan, raffinose, lignin, hemicelluloses

24
Q

cellulose

A

dietary fiber

B 1,4 linked glucose - cannot be cleaved by human enzymes

25
Q

raffinose =

A

sucrose + galactose

trisaccharide in beans, cause gas

26
Q

BEANO

A

alpha glucosidase breaks the B1,4 linkage in raffinose/trisaccharide in beans

27
Q

fate of indigestible food…

A

fermentation by colon bacteria producing

  • lactic acid, short chain FAs, and gases (H2, CO2, and CH4)
  • osmotic effect –> watery stool
  • malabsorption
28
Q

protein digestion pathway

A

starts in stomach – pepsin converts proteins to smaller polypeptides – in small intestine proteolytic enzymes from the pancreas cleave polypeptides into oligopeptides and AA – intestinal enzymes cleave the oligopeptides into AA –finally AA are absorbed by epithelium into blood

29
Q

proteolytic enzymes made by pancreas

A

trypsin, chymotrypsin, elastase, and carboxypeptidases

30
Q

proteolytic enzymes made by intestinal epithelium

A

aminopeptidases, dipeptidases, and tripeptidases

31
Q

inactive form of enzyme

A

zymogen

32
Q

how to activate a zymogen?

A

remove a peptide fragment

33
Q

functions of stomach low pH

A

kills bacteria and denatures proteins so that pepsin can cleave them into oligopeptides

34
Q

pepsin

A

made by chief cells as the inactive pepsinogen
HCL in stomach is secreted by parietal cells
HCl cleaves pepsinogen to pepsin

35
Q

parietal cells make?

chief cells make?

A

HCl

pepsinogen

36
Q

bicarbonate role in intestines

A

secreted by pancreas to neutralizes stomach pH so that enzymes can act

37
Q

endopeptidases vs exopeptidases

A

endo (trypsin, chymotrypsin, and elastase) cleaves peptide bonds in the middle of a chain
exo (carboxypeptidase A and B) cleave one at a time, peptide bonds at the ends of chain

38
Q

trypsinogen –> trypsin

A

by enteropeptidase

trypsin can also begin to cleave other trypsinogen and all other zymogens

39
Q

which enzyme can cleave all other zymogens and itself

A

trypsin

40
Q

chymotrypsinogen and proelastase

A

cleaved by trypsin into chymotrypsin and elastase

41
Q

procarboxypeptidases

A

cleaved by trypsin into carboxypeptidase A and B

42
Q

proteases made by epithelial cells in intestines

A 
finish conversion of proteins into aa
amino peptidases (one at a time) and di and tri peptidases
43
Q

sodium-aa carrier system

A

secondary active transport via atp hydrolysis of Na up its gradient into blood and aa travels down its gradient into blood

44
Q

passive (facilitative )absorption of monosaccharides and aa

A

GLUT transporters do not use ATP

glucose needs transporter because it is water soluble and cannot cross lipid bilayer

45
Q

GLUT

A

passive transporters; dont use ATP

46
Q

SGLT1 and 2

A

sodium-glucose linked transporters – active transport
secondary active NA-KATPase
1 is in intestines and kidney
2 is in kidney

47
Q

SGLT1 transports—
GLUT 5 transports…
GLUT2 transports…

A

sglt1 = glucose and galactose
glut5 = fructose
INTO enterocytes

glut2 transports glucose, fructose, and galactose from enterocyte into blood

48
Q

enzyme to break down fat?

A

pancreatic lipase

49
Q

fat digestion

A

begins in small intestine by pancreatic lipase which turns triacylglyceral into 2-monoacylglycerols and free FA –> packages into micelles

50
Q

gallbladder role in fat metabolism

A

gallbladder releases bile (bile salts and acids) to emulsify fats

51
Q

bile

A

made by liver and stored by gallbladder

used to emulsify fats

52
Q

bile salts are..

A

recycled; only 5% are excreted in poop which is the only way to get rid of cholesterols

53
Q

cmc

A

critical micelle concentration

minimum concentration at which a micelle will form

54
Q

lechitin is a

A

phospholipid (phosphatidylcholine)

used with bile salts to emulsify

GI First half (8 decks)

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