Lecture 19 - Digestion and Absorption of Protein Flashcards Preview

Fuel Metabolism - 2016 > Lecture 19 - Digestion and Absorption of Protein > Flashcards

Flashcards in Lecture 19 - Digestion and Absorption of Protein Deck (23):
1

_________ are enzymes that need to be cleaved at one or more sites in order to become active/functioning.

A. Proenzymes
B. Endopeptidases
C. Exopeptidases

A

2

__________ cleave proteins by hydrolyzing peptide bonds within the polypeptide chain.

A. Proenzymes
B. Endopeptidases
C. Exopeptidases

B

3

_________ cleave AA from either N or C terminal ends of peptides or proteins.

C

4

Pepsin is produced by what organ?

stomach

5

Trypsin and chymotrypsin are produced by what organ?

pancreas

6

Peptidases are produced by what organ?

small intestine

7

What are two non-enzymatic components of gastric juice?

1. Gastin
2. HCl

8

Gastrin acts on the _______ cells to secrete HCl.

parietal

9

Gastrin acts on the ________ cells to secrete pepsinogen.

chief

10

HCl decreases pH to denature protein and provide a proper environment for _______.

pepsin

11

Secretin and CCK are secreted in response to what?

Chyme moving through duodenum

12

Secretin stimulates the release of _________.

pancreatic juice

13

CCK stimulates the release of ___________ into the lumen of the small intestine.

pancreatic zymogens

14

Enteropeptidase catalyzes what reaction?

Conversion of trypsinogen to trypsin

15

What are the (2) products of protein digestion within the lumen of the small intestine?

35% neutral and basic AA
65% oligopeptides

16

In the pathway of AA transport from the lumen of the SI to the portal blood, AA first go through the brush border where they are further hydrolyzed by _____.

oligopeptidases

17

Dipeptides and tripeptides are taken up by AA transporters using a _________ and then hydrolyzed by peptidases in intestinal cells.

proton gradient

18

Transport proteins (most are Na+ dependent) take AA through the _______ membrane, from the intestinal cell to the portal blood.

basolateral

19

Enteropeptidases are found where?

Brush border of intestinal cells

20

If an AA can't be absorbed in the intestine, it also can't be absorbed in the ________ and is excreted.

kidney

21

Long-term use of proton pump inhibitors can result in _________________.

vitamin B12 deficiency

22

What are two enzymes that require B12 as a cofactor?

1. Methylmalonyl-CoA mutase (synthesizes succinyl-CoA in TCA cycle)
2. Methionine synthase

23

Succinyl-CoA is required for _________ synthesis, so a B12 deficiency results in megaloblastic anemia.

heme