Protein Digestion

Question 1

sources of amino acids

Answer 1

• body protein (major source)
• dietary protein
• digestive enzymes

Question 2

uses for amino acids

Answer 2

• synth of nitrogen containing compounds
• degradation for energy to make glucose
• protein synth
• poop production

Question 3

what concentration are amino acids maintained at in the blood

Answer 3

-high for use all over the body

Question 4

two sources of blood protein

Answer 4

• 3/4 body breakdown

- 1/4 dietary

Question 5

dietary protein digestion

Answer 5

• glands of the stomach secrete acid and pepsinogen
• acid denatures proteins and pepsin produces peptides
• peptides eneter the small intestine, pancreas secretes bicarb and zymogens
• activated enzymes in the duodenum digest long peptides into short ones
• enzymes of intestinal lumen and villi produce mostly amino acid for absorption

Question 6

pepsinogen

Answer 6

• is not active at neutral ph
• at higher ph, a pro-peptide is blocking the active site
• at lower ph, autoactivtion happen and the site is exposed

Question 7

regulation of digestion in the small intestine

Answer 7

• acid chyme passes to duodenum
• mucosal cells release of secretin and CCK into the blood
• gall bladder contracts and pancreas releases juices

Question 8

what does the pancreas secrete

Answer 8

• bicarb

- inactive zymogens (these are activated by enzymes from the duodenum)

Question 9

trypsinogen

Answer 9

• activated by enteropeptidase which starts off the process of digestion. made into trypsin
• trypsin acts on trypsinogen to turn it into trypsin
• activates chymotrypsinogen, proelastase, and procarboxypeptidase

Question 10

degradation of digestive enzymes

Answer 10

• they degrade themselves as they run out of dietary amino acids to work on
• degradation = production (70g/day)

Question 11

uninhibited trypsin in pancreatic cells

Answer 11

-leads to pancreatitis
-could be from a mutation
-

Question 12

carboxypeptidase produces

Answer 12

mostly amino acids

Question 13

aminopeptidases and dipeptidases produce

Answer 13

amino acids

Question 14

absorption uptake in and out of cells occurs via

Answer 14

• transporters
• there is a high aa concentration in cells so you must use energy to move amino acids in,
• you can just use facilitated transport to move amino acids out

Question 15

where does amino acid transport occur

Answer 15

• intestines from the lumen
• refiltered from urine in the kidney for reuse
• across mitochondrial membranes
• solute carrier transporters are a diverse group

Question 16

characterization of amino acid transporters

Answer 16

• often sodium linked transporters that use energy to pump sodium out of the cell in order to establish a sodium gradient that is used to pump the amino acids in (NA/K ATPase)
• one transporter will carry many aa’s that have similar characteristics

Question 17

where is the first place amino acids go

Answer 17

-liver via portal vein

Question 18

defective kidney transport for cystine

Answer 18

• can cause cystinuria
• carrier rate of 1:50
• resorption rate rises
• results in high cystein in urin and it is of limiited solubility so it results in stones
• also high lysine

Question 19

niacin (VB3)

• pellagra
• hartnip

Answer 19

• made from tryptophan
• deficiency disease, pllagra causes its victims to experience dermatitis, dirrhea, and dementia
• clinical features of hartnup disease are nearly identical to thos of pellagra, although more intermittent and slightly less than pellagra

Question 20

hartnup disease

Answer 20

• abnormal excretion of tryptophan into the urine and deficient in absorption in the intestine
• patient is characterized by intermittent attacks of dermatitis, diarrhea, and dementia
• tryptophan can be converted into niacin, a precursor to NAD
• affects occur in the brin and skin

Question 21

cathepsins

Answer 21

• lysosomal proteases

- effective for degrading extracellular proteins

Question 22

sources for amino acids from protein degradation oustide of dietary proteins

Answer 22

• lysosomal system (cathesins)
• digestive enzyme turnover
• the ubiquitin/proteasome pathway (UPP): major pathway for degradation of intracellular proteins (muscle)

Question 23

degradation rate of proteins

Answer 23

• varies

- proteins that shouldnt be around for a long time such as cell cycle proteins will degrade more quickly

Question 24

what happens to proteins that are destine for the ubiquitin pathway

Answer 24

• enzymes E1,2, and 3 add ubiquitin to the target which tags it for degradation
• final product is polyubiquitinated

Question 25

the proteasome

Answer 25

- present in the cytoplasm - composed of two regulatory particles and a core particle an - end product is amino acids - processing is upregulated when needed

Question 26

regulatory particle

Answer 26

- selects substrates - remoives Ub for recycling - edits wrongly tagged proteins

Question 27

core particle

Answer 27

-this is where proteins are digested into peptides of 7 to 10 aa's

Question 28

ubiquitin signals in the protein sequence and not variable

Answer 28

- N end rule: methionine is the slowest - PEST sequence - destruction boxes

Question 29

ubitquitin signals that are external and variable

Answer 29

- phosphoryltaion - denaturation/damage - facilitators/chaperons

Question 30

HPV E6

Answer 30

- faciliates the degradation of p53 - this protein forma complex with its target and makes it more likely to be ubiquinylated - this is a viral protein which upregulates the cell cycle by degrading p53, a powerful tumor supressor - certain forms of the virus are assoicated with cervical cancer

Question 31

parkinsons

Answer 31

- lewy bodies (protein deposits in the brain) - causes a loss of neurons, dopamine - L dopa is the most common treatment

Question 32

parkin and E6AP

Answer 32

-examples od E3 type ubitquitin ligases that are associated with parkinsons and HPV induced disease

Question 33

plasma

Answer 33

- this is how proteins are transported in the blood | - alanine and glutamine are in the highest concentration due to the way they are metabolized

Question 34

free amino acids

Answer 34

levels are low compared to that of polymerized aa's | -95% is turned over every ten mins

Question 35

essential amino acids

Answer 35

-must be obtained from the fiet -if something is too hard to make, we eat it -

Question 36

list the essential amino acids

Answer 36

- arg - val - phe - his - thr - met - iso - lys - leu - tryp - are valuable phor his thriving metabolism in lyfes leunatic tryp

Question 37

inadequate protein in the diet

Answer 37

- kwashiorkor - marasmus - bloated stomachs due to loss of plasma protein and fatty liver

Question 38

quality sources of protein

Answer 38

- animal proteins is of much higher percentage and is broken down much easier - animal has complete amino acid sources - chemical score for animal is high