Biochem - macronutrients digestions Flashcards Preview

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Flashcards in Biochem - macronutrients digestions Deck (54)
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1

bonds in proteins? in fats?

proteins have peptide bonds
fats have ester bonds

2

class of enzymes that perform hydrolysis?

hydrolases

3

2 main disaccharides in diet?

lactose and sucrose

4

lactose =

galactose + glucose

5

sucrose =

fructose + glucose

6

starch

polysaccharides of glucose; contains amylose and amylopectin

7

amylose

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

8

amylopectin

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

9

what enzyme works in mouth? what does it do?

salivary alpha amylase
cleaves starch by breaking the 1,4 linkages between glucose --> this creates dextrins

10

dextrins

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

11

digestion that started in the stomach is continued ...

in the intestines by pancreatic alpha amylase

12

salivary and pancreatic alpha amylases are...

both endo-glucosidases found in the brush border

13

intestinal absorption : aa vs fats

aa absorbed by villi and enter portal vein --> liver
fats dont go through portal vein - they go into lymph as chylomicrons

14

what neutralizes stomach acid in the small intestine

bicarbonate from the pancreas

15

products of pancreatic alpha amylase on glucose

disaccharides maltose and isomaltose, trisaccharides, and small oligosaccharides

16

what is digested at brush border?

sucrose, lactose, and starch products

17

4 brush border enzymes...

hydrolyze di, tri, and oligo saccharides into monosaccharides

glucoamylase
isomaltase
sucrase
lactase

18

glucoamylase

also called alpha glucosidase
cleaves glucose from nonreducing ends of oligosaccharides

19

sucrase

converts sucrose into glucose and fructose

20

lactase

also called beta galactosidase
cleaves lactose into galactose and glucose

21

transport in intestines

glucose and Na+ are transported by secondary active transport

22

B-galactosidase deficiency

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

dietary fiber

carbs that cannot be digested
=cellulose, carragennan, raffinose, lignin, hemicelluloses

24

cellulose

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

25

raffinose =

sucrose + galactose
trisaccharide in beans, cause gas

26

BEANO

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

27

fate of indigestible food...

fermentation by colon bacteria producing
-lactic acid, short chain FAs, and gases (H2, CO2, and CH4)
-osmotic effect --> watery stool
-malabsorption

28

protein digestion pathway

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

proteolytic enzymes made by pancreas

trypsin, chymotrypsin, elastase, and carboxypeptidases

30

proteolytic enzymes made by intestinal epithelium

aminopeptidases, dipeptidases, and tripeptidases