s2m1 biochem – digestion Flashcard

what does a-amylase do?

cleaves a-1,4 glycosidic bonds in starch & glycogen

forms maltose, maltotriose, a-limit dextrins

what does lysosyme do?

what specifically does it target?

cleaves B-1,4 glycosidic bonds in bacterial cell wall

kills gram-postive bacteria (gram-neg are protected by outer cell wall)

3 functions of hydrochloric acid?



denature proteins

create right pH for pepsin

3 problems with total gastrectomy


1. mild digestive problems

2. incr risk of intestinal infections

3. VitB12 supplements needed

what are the 3 serine proteases? where do they cleave?

where are they found?

trypsin: carboxy side of Lys & Arg

chymotrypsin: carboxy side of hydrophobic aa

elastase: carboxy side of small aa

they’re in the pancreas

what are the two carboxypeptidases?

what do they contain?

where are they synthesized?

carboxypeptidase A: cleaves off hydrophobic aa

carboxypeptidase B: cleaves of basic aa (lys, arg)

they contain zinc

they’re made in the pancreas

what does lipase cut up?

what two things are also required?

where is lipase synthesized?

digestion of fat (triglyceride)

also need Co-lipase – achors lipase to surface of fat droplets

bile salts – decrease droplet size

lipase is made in the pancreas

what to phospholipases & nucleases cleave?

where are these synthesized?


nucleic acids

made in the pacreas

what can pancreatic failure cause?

steatorrhea (fatty poop stool)

generalized lipid malabsorption

deficiency in fat-soluble vitamins


where found?

what digest?

found in the intestinal brush border

complete digestion of proteins

endo- and carboxypeptidases digest what?

where found?

digest oligopeptides

found in the intestinal brush border

sucrase – what cleave?

lactase – what cleave?


where found?

sucrase – cleave sucrose to glucose + fructose

lactase – cleave lactose to glucose + galactose

found in the intestinal brush border

glycoamylase – what does it do?

where is it found?

removes glucose from non-reducing end of starch

found in the intestinal brush border

what does iso-maltase digest?

where is it found?

it cleaves a-1,6 bonds in isomaltose & a-limit dextrins

found in the intestinal brush border

what does trehalase do?

where is it found?

cleaves trehelose

found in the intestinal brush border

give examples of undigestable material

what happens to this stuff?


plant cell walls, cellulose, lignin, pectin 


fermented by colon bacteria

forms lactic, acetic, propionic acid & farts


3 causes of lactose intolerance


1. congenital hypolactasia

2. pirmary hypolactasia – decreased lactose activity after weaning

3. secondary – after damage to intestinal mucosa


undigested lactose -> farts, abdominal pain, diarrhea

what are zymogens?

what are two proteases that are not made as zymogens?

what are they all activated by?

what activates that compound?

what’s the safety mech in the pancreas?

they’re precursors (inactive) proteases

glycosidase & lipase


which is activated by enteropeptidase

a small pancreatic peptide molecule that binds trypsin with high affinity

what’s the zymogen of pepsin?

how is it activated?

when does this happen?

what’s the inhibitory mech?

it’s derived from pepsinogen

an amino acid peptide is cleaved from the amino end

it can happen automatically in low pH

the cleaved peptide acts as an inhibitor at neutral pH

how does acute pancreatitis occur?


if the enzymes in the pancreas spill out into the abdominal cavity

start digesting everything including the pancreas itself (cuz of amylase ; lipase)

where do fatty acids, mono- ; diacylglyderol go to?

what are they bound here?

what happens then?

where do they go from here?

they’re absorbed into a enterocyte with the fat soluble vitamins

inside the enterocyte they’re bound to Intestinal FA binding protein.

re-synthesis of triacylglycerol

packed into lipoproteins (chylomicrons) -; released to lymphatics

where and how are chylomicrons made?

where does it travel?

what does it loose in the periphary? via what enzyme?

what do the remnants do?

made of dietary fat, phospholipid, cholesterol in the intestines

-; lymphatics -; bloodstream

LPL (lipoprotein lipase) on adipose tissue etc. cut out the FA’s & monoacylglycerol

Chylomicron remnant back in blood to deliver cholesterol to liver


ethanol detox pathway?

where are the two enzymes located?

what’s the metabolic gain from alcohol?

what’s the drawback of it’s products?

ethanol -; (alcohol dehydrogenase in cytosol) ethanal -; (aldehyde dehydrogenase in mitochondria) acetic acid

no metabolic gain, however ATP ; NADPH, acetyl-CoA are produced

these inhibit glycolysis (PFK), B-oxidation, Krebs Cycle



in alcohol metabolism you get excess ATP, NADH ; acetyl-CoA

what are the neg consequences to these products?

long term problems?

ATP inhibit glycolysis, krebs cycle

NADH inhibit gluconeogenesis -; result in acidosis, hypoglycemia

Acetyl-CoA is converted to triglycerides -; lead to lipidemia, fatty liver

long term:

hepatocytes get replaced by cirrhosis

mitochondrial damage

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