Biochem - macronutrients digestions

Question 1

bonds in proteins? in fats?

Answer 1

proteins have peptide bonds

fats have ester bonds

Question 2

class of enzymes that perform hydrolysis?

Answer 2

hydrolases

Question 3

2 main disaccharides in diet?

Answer 3

lactose and sucrose

Question 4

lactose =

Answer 4

galactose + glucose

Question 5

sucrose =

Answer 5

fructose + glucose

Question 6

starch

Answer 6

polysaccharides of glucose; contains amylose and amylopectin

Question 7

amylose

Answer 7

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

Question 8

amylopectin

Answer 8

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

Question 9

what enzyme works in mouth? what does it do?

Answer 9

salivary alpha amylase

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

Question 10

dextrins

Answer 10

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

Question 11

digestion that started in the stomach is continued …

Answer 11

in the intestines by pancreatic alpha amylase

Question 12

salivary and pancreatic alpha amylases are…

Answer 12

both endo-glucosidases found in the brush border

Question 13

intestinal absorption : aa vs fats

Answer 13

aa absorbed by villi and enter portal vein –> liver

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

Question 14

what neutralizes stomach acid in the small intestine

Answer 14

bicarbonate from the pancreas

Question 15

products of pancreatic alpha amylase on glucose

Answer 15

disaccharides maltose and isomaltose, trisaccharides, and small oligosaccharides

Question 16

what is digested at brush border?

Answer 16

sucrose, lactose, and starch products

Question 17

4 brush border enzymes…

Answer 17

hydrolyze di, tri, and oligo saccharides into monosaccharides

glucoamylase
isomaltase
sucrase
lactase

Question 18

glucoamylase

Answer 18

also called alpha glucosidase

cleaves glucose from nonreducing ends of oligosaccharides

Question 19

sucrase

Answer 19

converts sucrose into glucose and fructose

Question 20

lactase

Answer 20

also called beta galactosidase

cleaves lactose into galactose and glucose

Question 21

transport in intestines

Answer 21

glucose and Na+ are transported by secondary active transport

Question 22

B-galactosidase deficiency

Answer 22

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

Question 23

dietary fiber

Answer 23

carbs that cannot be digested

=cellulose, carragennan, raffinose, lignin, hemicelluloses

Question 24

cellulose

Answer 24

dietary fiber

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

Question 25

raffinose =

Answer 25

sucrose + galactose | trisaccharide in beans, cause gas

Question 26

BEANO

Answer 26

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

Question 27

fate of indigestible food...

Answer 27

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

Question 28

protein digestion pathway

Answer 28

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

Question 29

proteolytic enzymes made by pancreas

Answer 29

trypsin, chymotrypsin, elastase, and carboxypeptidases

Question 30

proteolytic enzymes made by intestinal epithelium

Answer 30

aminopeptidases, dipeptidases, and tripeptidases

Question 31

inactive form of enzyme

Answer 31

zymogen

Question 32

how to activate a zymogen?

Answer 32

remove a peptide fragment

Question 33

functions of stomach low pH

Answer 33

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

Question 34

pepsin

Answer 34

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

Question 35

parietal cells make? | chief cells make?

Answer 35

HCl | pepsinogen

Question 36

bicarbonate role in intestines

Answer 36

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

Question 37

endopeptidases vs exopeptidases

Answer 37

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

Question 38

trypsinogen --> trypsin

Answer 38

by enteropeptidase | trypsin can also begin to cleave other trypsinogen and all other zymogens

Question 39

which enzyme can cleave all other zymogens and itself

Answer 39

trypsin

Question 40

chymotrypsinogen and proelastase

Answer 40

cleaved by trypsin into chymotrypsin and elastase

Question 41

procarboxypeptidases

Answer 41

cleaved by trypsin into carboxypeptidase A and B

Question 42

proteases made by epithelial cells in intestines

Answer 42

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

Question 43

sodium-aa carrier system

Answer 43

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

Question 44

passive (facilitative )absorption of monosaccharides and aa

Answer 44

GLUT transporters do not use ATP | glucose needs transporter because it is water soluble and cannot cross lipid bilayer

Question 45

GLUT

Answer 45

passive transporters; dont use ATP

Question 46

SGLT1 and 2

Answer 46

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

Question 47

SGLT1 transports--- GLUT 5 transports... GLUT2 transports...

Answer 47

sglt1 = glucose and galactose glut5 = fructose INTO enterocytes glut2 transports glucose, fructose, and galactose from enterocyte into blood

Question 48

enzyme to break down fat?

Answer 48

pancreatic lipase

Question 49

fat digestion

Answer 49

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

Question 50

gallbladder role in fat metabolism

Answer 50

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

Question 51

bile

Answer 51

made by liver and stored by gallbladder | used to emulsify fats

Question 52

bile salts are..

Answer 52

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

Question 53

cmc

Answer 53

critical micelle concentration | minimum concentration at which a micelle will form

Question 54

lechitin is a

Answer 54

phospholipid (phosphatidylcholine) | used with bile salts to emulsify