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Biochemistry > Lab 4 - Exam. of E of digestion > Flashcards

Lab 4 - Exam. of E of digestion Flashcards

1
Q

Degradation of N-compounds

A

Begins in stomach.
-Ru: forestomach by symbiotic microbes. Urease splits urea into NH3, which is a N-source for microbial protein synthesis.

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2
Q

Proteases

A 
Protein-degrading E.
1.Endopeptidases: split proteins inside the chain
2.Exopeptidases: 
-aminopeptidases: split N-term.
-carboxypeptidases: split C-term.
Not S-specific.
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3
Q

Degradation of protein

A

1.Stomach. Ru: forestomach. Pepsin.
Calfs: Rennin prod. in abomasum.
2.Pancreas: Trypsin
3.Exopeptidases

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4
Q

Rennin

  • Also called?
  • Criterias to function as E
  • Function
A
  • Chymosin.
  • Presence of Ca2+ in slightly acidic pH.
  • Low degree hydrolysis. Degrade casein(milk)->paracasein. Clotting of milk.
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5
Q

Pepsine

  • Prod?
  • Function?
A
  • HCl in stomach turn inactive pepsinogen to active pepsin.

- Provide optimal pH for E. Split peptide bonds in Phe and Leu.

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6
Q

Trypsin

  • Prod.?
  • Function?
  • Opt.pH?
A
  • Enteropeptidase prod. in small intestines, turn inactive trypsinogen prod. in pancreas, to active trypsin.
  • Split peptide bonds in Arg and Lys.
  • 7-9
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7
Q

Degradation of carbohydrates

A
  • Some sp, eg. pig: Begins in mouth by amylase from saliva.
  • In stomach low pH (HCl)-inhibits starch hydrolysis.
  • Amylase from pancreas and small intestines finish starch hydrolysis.
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8
Q

Degradation of fats and oils

  • By?
  • Absorption?
  • What increases their degradability?
A
  • By lipase prod. in pancreas and intestinal wall.
  • Simple fats absorbed as 2-monoacyl glycerol, or as fatty acids and glycerol.
  • Bile salts increase water solubility of fats and thus their degradability by enzymes.
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9
Q

Lipase

  • Function?
  • Opt.pH?
  • What can promote it´s function?
A
  • Splits glycerol in fatty acids.
  • 7.8
  • Ca2+ ions
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10
Q

Which E is prod. by…

  1. Oral cavity
  2. Stomach
  3. Rumen
  4. Abomasum(calf)
  5. Pancreas
  6. Small intestines
A
  1. Salivary amylase
  2. Pepsin
  3. Urease
  4. Rennin(chymosin)
  5. Pancreatic amylase and lipase, trypsin, chymotrypsin
  6. Lipase, enteropeptidase
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11
Q

Materials used in “detection of labferment (rennin, chymosin)”?

A
  • Milk
  • Rennin sol.
  • Ammonium oxalata
  • CaCl2
  • Water bath at 37 degrees
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12
Q

Materials used in “measuring the pepsin activity, dependence of the velocity of the R on the actual pH”?

A
  • Diluted blood plasma
  • Pepsin sol.
  • HCl
  • Na2CO3
  • Trichloroacetic acid
  • Spectrophotometer
  • Water bath at 37 degrees
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13
Q

Role of tubes in “Measuring the pepsin activity, dependence of the velocity of the R on the actual pH”?

A 
1.Dist. water and pepsin: Blank for spectrophotometry
All others have blood plasma and pepsin
2.HCl: pH≈1.5
3.Dist.water: pH≈7
4.Na2CO3: pH≈10
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14
Q

How do we measure the pepsin activity?

A

Measuring amount of tyrosine and thryptophan - by Folin´s method - pos.

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15
Q

How does TCA react in “Measuring the pepsin activity, dependence of the velocity of the R on the actual pH”?

A

It ppt. the undigested proteins and polypeptides. But oligopeptides and A.a. prod. by enzymatic hydrolysis of proteins are soluble in TCA.

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16
Q

Materials used in “Digestion of milk fat by lipase from pancreas”?

A
  • Pancreas extract (drug)
  • Boiled milk
  • 0.2M phospate buffer, pH=7.8
  • 0.21M ammonium oxalate sol.
  • Bile or cholic acid (replaced by detergent)
  • Phenolphtalein
  • NaOH
  • Water bath at 37 degrees
17
Q

Background of “Measuring the pepsin activity, dependence of the velocity of the R on the actual pH”?

A

The liberated fatty acids (splitted from glycerol by Lipase) causes acidic pH of the medium. This can be titrated by alkaline and the amount can be estemated by a calibration curve.

18
Q

Materials used in “Measuring the trypsin activity”?

A
  • Pancreatic extract (drug)
  • Dilated blood plasma
  • TCA
  • Folin´s 1+2
  • Phosphate buffer (0.2M, pH7.8)
  • Spectrophotometer
  • Water bath at 37 degrees
19
Q

Background of “Measuring the trypsin activity”?

How will the activity be measured?

A

TCA ppt. undigested proteins and polypeptides. But oligopeptides and A.a. prod. by the E hydrolysis of proteins, are soluble in TCA.
Activity measured by amount of tyrosine and tryptophan-Folin´s method-pos.

20
Q

All labtests

A
  1. Detection of labferment (rennin, chymosin)
  2. Digestion of milk fat by lipase from pancreas
  3. Measuring the pepsin activity, dependence of the velocity of the R on the actual pH
  4. Measuring the trypsin activity

Biochemistry (16 decks)

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