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Biochemistry > Module 11: Amino Acid Metabolism (Part 02) > Flashcards

Module 11: Amino Acid Metabolism (Part 02) Flashcards

1
Q

Protein digestion (denaturation and hydrolysis) starts where?

A

Stomach
(1) Denatured by HCl in gastric juice (pH of 1.5-2.0)
(2) Enzyme pepsin hydrolyzes about 10% peptide bonds

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2
Q

What is the pH of the small intestine that helps neutralize the acidified gastric content?

A

7.0 - 8.0

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3
Q

These are released into the small intestine help hydrolyze . proteins to smaller peptides

A

Trypsin, chymotrypsin and carboxypeptidase in pancreatic juice

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4
Q

This secreted by intestinal mucosal membrane further hydrolyze the small peptides to amino acids

A

Aminopeptidase

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5
Q

Amino acids liberated are transported into the blood stream via what?

A

Active Transport

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6
Q

In infants the transport of polypeptides allows the passage of what?

A

proteins such as antibodies in colostral milk from a mother to a nursing infant to build up immunologic protection in the infant.

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6
Q

Enzymes (Trypsin, chymotrypsin carboxypeptidase , and aminopeptidase) are produced in inactive forms called ____________that are activated at their site of action.

A

zymogens

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7
Q

This is the total supply of free amino acids available for use in the human body.

A

Amino Acid Pool

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8
Q

Amino acid pool is derived from three sources namely?

A

(1) Dietary protein
(2) Protein turnover: A repetitive process in which the body proteins are degraded and resynthesized
(3) Biosynthesis of amino acids in the liver

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9
Q

This is the repetitive process in which the body proteins are degraded and resynthesized

A

Protein Turnover

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10
Q

Explain the cycle of protein digestion and absorption based on site.

A

(1) Mouth
(2) Stomach
(3) Small Intestine
(4) Intestinal Lining
(5) Release of amino acids in the blood stream

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11
Q

The state that results when the amount of nitrogen taken into the human body as protein equals the amount of nitrogen excreted from the body in waste materials

A

Nitrogen Balance

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12
Q

In this form of nitrogen balance, protein degradation exceeds protein synthesis. The amount of N in urine exceeds nitrogen consumed. It results in tissue wasting

A

Negative Nitrogen Imbalance

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13
Q

In this form of nitrogen imbalance, the rate of protein synthesis (anabolism) is more than protein degradation (catabolism). This results in large amounts of tissue synthesis. It occurs during growth, pregnancy, etc.

A

Positive Nitrogen Imbalance

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14
Q

How are amino acids from the amino acid pool used?

A

(1) Protein Synthesis, where about 75% of amino acids are needed for tissue replacement and tissue growth
(2) Synthesis of non protein nitrogen containing compounds
(3) Synthesis of non essential amino acids
(4) Product of energy

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15
Q

These are synthesized for nucleic acid synthesis/

A

Purines and pyrimidines

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16
Q

This is synthesized for hemoglobin, neurotransmitters and hormones.

A

Heme

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17
Q

What happens to the nitrogen ion in degradation pathways

A

The amino nitrogen atom is removed and converted to ammonium ion, which ultimately is excreted from the body as urea.

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18
Q

What happens to the remaining c skeleton in degradation pathways?

A

The remaining carbon skeleton is then converted to pyruvate, acetyl CoA, or a citric acid cycle intermediate, depending on its makeup, with the resulting energy production or energy storage.

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19
Q

Degradation of amino acid takes places in 2 stages?

A

(1) The removal of the -amino group and
(2) The degradation of the remaining carbon skeleton

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20
Q

This is a biochemical process in which the amino group of an alpha-amino acid is transferred to an alpha-keto acid.

A

Transamination

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21
Q

What does transamination involve?

A

Involves transfer of the amino group of an alpha- amino acid to an alpha keto acid

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21
Q

This is when an amino acid is converted into the corresponding keto acid by the removal of the amine functional group as ammonia and the ammonia eventually goes into the urea cycle.

A

Oxidative Deamination

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22
Q

What kind of reaction is transamination?

A

Enzyme catalyzed reaction

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23
Q

There are at least _____transaminase enzymes associated with transamination reactions

A

50

24
Q

What is the initial effect of transamination?

A

Collect the amino groups from a variety of amino acids into just two amino acids—glutamate (most cells) and alanine (muscle cells)

25
Q

What is the net effect of transamination?

A

Collection of the amino groups from a variety of amino acids into a single compound—the amino acid glutamate

26
Q

What is the goal of transamination?

A

To regenerated pyruvate and oxaloacetate for further transamination reactions

27
Q

This is liberated from the glutamate amino acid formed from transamination

A

Ammonium ion (NH4+)

28
Q

This is a biochemical reaction catalyzed by glutamate dehydrogenase in which glutamate is converted into alpha-keto glutarate with the release of an ammonium ion

A

Oxidative Deamination

29
Q

Where does Oxidative Deamination occur?

A

(1) liver
(2) kidney

30
Q

What happens to the ammonium ion produced by oxidative deamination?

A

The ammonium ion produced by oxidative deamination is a toxic substance, so it is quickly converted carbonyl phosphate and then to urea via the urea cycle in mammals

31
Q

These two amino acids undergo direct deamination by dehydration-hydration process rather than oxidative deamination

A

(1) Serine
(2) Threonine

32
Q

This is a series of biochemical reactions in which urea is produced from ammonium ions and carbon dioxide.

A

Urea cycle

33
Q

This is transported via the blood from liver to the kidneys and eliminated from the body via urine. This is a white solid substances that is very soluble in water and is odorless as well as colorless and has a salty taste.

A

Urea

34
Q

This is the fuel for the urea cycle. It contains a high energy phosphate bond and takes place in the mitochondrial matrix.

A

Carbamoyl Phosphate

34
Q

what is the melting point of urea?

A

133

35
Q

How many ATP molecules are expended in the formation of one carbamoyl phosphate molecule

A

Two

36
Q

What happens in step 1 of the urea cycle?

A

The carbamoyl group of carbamoyl phosphate is transferred to ornithine to form citrulline

37
Q

What happens in step 2 of the urea cycle?

A

Citrulline is transported into the cytosol, citrulline reacts with aspartate to produce argininosuccinate utilizing ATP

38
Q

In step 02 where are the nitrogen atoms from?

A

In this reaction the second of two nitrogen atoms of urea is introduced into the cycle (One nitrogen comes from carbamoyl phosphate and the other from aspartate – original source of both is glutamate)

39
Q

What happens in step 03 of the urea cycle?

A

Argininosuccinate is cleaved to arginine and fumarate by the enzyme argininosuccinate lyase

40
Q

What happens in step 4 in urea cycle?

A

Hydrolysis of arginine produces urea and regenerates ornithine - one of the cycle’s starting materials. The oxygen atom present in the urea comes from water. Orthinine is transported back to mitochondria to be used in the urea cycle

41
Q

This is produced is used in citric acid cycle

A

Fumarate

42
Q

This is produced through transamination is used in the urea cycle at step 2

A

Aspartate

43
Q

Transamination and oxidative deamination produces an

A

alpha-keto acid that contains the carbon skeleton from the amino acid

44
Q

What are the degraded products?

A

Degraded products are pyruvate, acetyl CoA, acetoacetyl CoA, alpha-ketoglutarate, succinyl CoA, fumarate, and oxaloacetate

45
Q

Non essential amino acids are synthesized in __________

A

1-3 steps

46
Q

Essential amino acids are synthesized in _______

A

7-10 steps

47
Q

These are highly specialized cells whose primary function is to deliver oxygen to cells and remove carbon dioxide from body tissues

A

Red blood cells

48
Q

Do mature red blood cells have nucleus or DNA

A

NO

49
Q

Where are red blood cells formed and how many are formed daily?

A

Bone marrow, 200 billion

50
Q

How much is the life span of red blood cells

A

4 months

51
Q

What are the two parts of hemoglobin

A

Protein portion is globin
Prosthetic group is heme

52
Q

This interacts with oxygen forming a reversible complex (oxygen can come on and off) with it

A

Iron atom

53
Q

How is hemoglobin degraded?

A

(1) Globin protein part is converted to amino acids and are put in amino acid pool
(2) Fe atom becomes part of ferritin – an iron storage protein – saves the iron for use in biosynthesis of new hemoglobin molecules
(3) The heme (tetrapyrrole) is degraded to bile pigments and eliminated in feces or urine

54
Q

This is green in color

A

Biliverdin

55
Q

This is reddish orange in color.

A

Bilirubin

56
Q

This is brownish in color (gives feces their characteristic brown color).

A

Stercobilin

57
Q

This is yellow in color and present in urine (gives characteristic yellow color to urine

A

Urobilin

58
Q

Daily normal excretion of bile pigments: _______ in urine and _________ in feces.

A

1–2 mg; 250–350 mg

59
Q

This condition results from liver, spleen and gallbladder malfunction. Also forms in higher than normal bilirubin levels in the blood and gives the skin and white of the eye yellow tint.

A

Jaundice

Biochemistry (16 decks)

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