Flashcards in EXAM #1: BIOCHEMISTRY OF THE GI TRACT Deck (66)
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1
What enzymes are contained in the mouth that begin the breakdown of food?
1) Alpha-amylase
2) Lingual lipase
2
What is the function of alpha-amylase?
Breakdown of starch in the mouth
3
What is the function of lingual lipase?
Breakdown of TAGs in the mouth
4
What macronutrient is NOT brokendown in the mouth?
Protein
5
What are the components of gastric juice that breakdown food?
1) HCl
2) Pepsin
6
What is the inactive zymogen form of pepsin?
Pepsinogen
7
What converts pepsinogen into its active form?
Secretion of HCl that lowers the pH of the gastric juice
8
What are the three functions of HCl in the stomach?
1) Initial breakdown of protein
2) Activation of pepsinogen to pepsin
3) Kill microorganisms
9
What enzymes are produced by the pancreas?
Amylase
Lipase
Peptidase
10
In addition to enzymes, what else does the pancreas secrete?
NaCl
NaHCO3
11
What pancreatic enzyme is secreted in its active form?
Pancreatic alpha-amylase
12
What is the function of bile acids?
Emulsificaiton of aggregated lipids to make them more accessible for lipid digestion enzymes
13
What form must carbohydrates be absorbed in in the small intestine?
Monosaccharide
14
What are the common sources of glucose?
Honey
Fruit
Corn syrup
15
What are the common sources of fructose?
Honey
Fruit
16
What is the common source of sucrose?
Table sugar
17
What is amylose?
Plant carbohydrate/ starch with alpha 1,4 glycosidic bonds
18
What is amylopectin?
Plant carbohydrate/starch with alpha 1,4 glycosidic bonds AND alpha 1,6 branches
19
What is the specific molecular function of alpha-amylase?
Hydrolysis of non-terminal alpha-1,4 linkages
20
What is the function of pancreatic alpha-amylase?
Conversion of branched polysaccharides into oligosaccharide units in the small intestine
21
What are the end products of pancreatic alpha-amylase digestion?
1) Maltose
2) Maltotriose
3) alpha-limit dextrins
22
What is cellulose? Why can't humans breakdown cellulose?
Polysaccharide plant cell wall component with BETA 1,4 GLYCOSIDIC BONDS
****Humans don't have BETA 1,4 ENDOGLYOCSIDASES to breakdown cellulose
23
What is Chitin? Why can't humans breakdown Chitin?
Polymer of N-acetyl-glucosamine with Beta 1,4 Glycosidic bonds that we do not have the enzymes to breakdown
****Comes from fungi and arthropods*****
24
How are the oligosaccharides made by alpha-amylase broken down into monosaccharides?
Membrane bound glycosidases on the luminal side of small intestine enterocytes
25
What is lactose hydrolyzed into via lactase?
1) Glucose
2) Galactose
26
What is maltose hydrolyzed into via maltase?
2x Glucose
27
What is sucrose hydrolyzed to via sucrase/isomaltase?
1) Glucose
2) Fructose
28
What transporter transports glucose across the membrane of the enterocyte for absorption?
Na+/Glucose cotransporter SGLT1
29
What transporter transports fructose across the enterocyte membrane for absorption?
Facilitated diffusion transporter, GLUT5
30
