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Bch 201 > Protein Matebolis > Flashcards

Protein Matebolis Flashcards

1
Q

Essential and NON essential amino acids

  • NON-ESSENTIAL: the organism (can or can’t?) synthesize the ____ analog.
  • ESSENTIAL: the organism (can or can’t ?) synthesize their carbon skeletons, so must ______
A

a-keto

Can

Can’t

obtain these amino acids in the diet.

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2
Q

Essential must get in diet Non-essential mammals synthesize

  • __* (children only)
  • ____* (children only)
  • list the rest
A

Arg
His

Ile                                                               
•Leu                               
•Lys                               
•Met                                                                                                  
•Phe                               
•Thr                               
•Trp                               
•Val
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3
Q

•Dietary proteins (can or cannot?) be absorbed directly from the intestine.

A

Cannot

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4
Q

To be absorbed, dietary protein must be digested into small simple molecules (______) which are easily absorbed into the small intestine.

A

amino acids

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5
Q

Protein digesting enzymes are produced in the (active or inactive ?) form (_____) in the gastro-intestinal tract to prevent ________ of _____

They are activated when protein from food is to be digested.

A

Inactive

zymogen

digestion of the tissue.

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6
Q

Steps in Protein digestion

•Protein digestion starts in the _______.

A

stomach

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7
Q

Steps in Protein digestion

The ___ juice produced in the stomach contains _____ and _____

Pepsinogen is activated to pepsin by ____.

  • Further activation of pepsinogen occurs when the pepsin produced cleaves a ____ residue peptide from the _____ terminal end of pepsinogen.
  • Pepsin hydrolyses peptide bonds between ____ amino acids and ____ amino acids in the protein.
  • The partially digested protein moves into the _____
A

Gastric

pepsinogen and HCl.

HCl

forty four ; amino

aromatic; acidic

small intestine.

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8
Q

Steps in Protein digestion contd.

•The pancreatic juice produced by the pancreas contains inactive protein digesting enzymes namely ______,______,_____

A

trypsinogen, chymotrypsinogen and procarboxy-peptidase.

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9
Q

Trypsinogen is activated to trypsin by ______ from ____ cells.

Further activation of trypsinogen occurs as the trypsin already formed cleaves the peptide bond between _____ and ______ in a ____peptide.

•Trypsin hydrolyzes peptide bonds where ___ amino acids (Arg, Lys, His) in the polypeptide chain contribute the ______ group.

A

enteropeptidase; duodenum

lysine and isoleucine; octa

basic; carboxylic

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10
Q

Steps in Protein digestion contd.

•Chymotrypsinogen is activated by ____ to __-chymotrypsin by removing a short peptide from it

A

trypsin; b

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11
Q

Steps in Protein digestion contd

β-chymotrypsin is activated to a-chymotrypsin by _______ by removing another short peptide from it.

α-chymotrypsin cleaves peptide bonds where ______ amino acids contribute the ______ group.

A

chymotrypsin

aromatic; carboxylic

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12
Q

Steps in Protein digestion contd

Procarboxy-peptidase is activated by ____ to carboxypeptidase.

The active enzyme hydrolyses ___ peptide linkage with _______ group.

A

trypsin

end; free carboxylic

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13
Q

Steps in Protein digestion contd

Succus entericus produced by ______ cells contains _________ and _____

A

intestinal mucosa

aminopeptidase and dipeptidase.

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14
Q

Aminopeptidase splits off ____ amino acid with _____ group.

Dipeptidase hydrolyses _____ to _____ which are the end products of protein digestion.

A

terminal

free amino

dipeptides to free amino acid

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15
Q

SPECIFIC ROLES IN PROTEIN DIGESTION

1.Digestion in the stomach
Protein digestion begins in the stomach by gastric juice.

B.Role of gastric HCL
●It causes ______ of proteins
●It converts proteins to _______, which are easily digested.
●It activates pepsinogen to ___.
●It makes ___ in the stomach suitable for the action of pepsin.

A

denaturation

metaproteins

pepsin

pH

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16
Q

Pepsin

  • It is an (endo or exo?) peptidase acting on ____ peptide bond in which amino group belongs to aromatic amino acids e.g phenylalanine, tyrosine and tryptophan.
  • It is secreted in an inactive form called pepsinogen.
  • Its optimum pH is __-___
  • It is activated by ____ then by _____.
A

Endo

central

1.5-2.2.

HCL

autoactivation

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17
Q

Renin
•It is a ____________ enzyme.
•It is present in stomach of _____ and ______
•Its optimum pH is ___.
•It acts on casein converting it to (soluble or insoluble?) ____, which in turn binds ____ ions forming (soluble or insoluble?) ___________ which is then digested by ____

A

milk-clotting

infants and young animals.

4

Soluble; paracasein; calcium

Insoluble

calcium paracaseinate

pepsin

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18
Q

Gelatinase
It is an enzyme that _______ ———

The end products of protein digestion in the stomach are ————,———,——-

A

liquefies gelatin.

proteases, peptones and large polypeptides.

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19
Q

Digestion in the small intestine
Digestion of protein is completed in the small intestine by proteolytic enzymes present in _____ and _____ juices.

A. Trypsin
•It is an (endo or exo?) peptidase that hydrolyzes ____ peptide bond in which the carboxyl group belongs to ___ amino acids. E.g. arginine, lysine and histidine.
•It is secreted in an inactive form called ____.
•Its optimum pH is __
•It is activated by _____ enzyme then by _____.

A

pancreatic and intestinal

Endo

central; basic

trypsinogen

8

enterokinase

autoactivation

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20
Q

Chymotrypsin
•It is an (endo or exo?) peptidase that hydrolyze central peptide bond in which the carboxyl belongs to ____ amino acids.
•It is secreted in an inactive form called _____.
•It is activated by ___.
•Its optimumpH is __

A

Endo; aromatic

chymotrypsinogen

trpsin

8

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21
Q

Elastase
It is an (endo or exo?) peptidase acting on peptide bonds formed by ____,____,____
It is secreted in an inactive form called ____.
It is activated by ____.
It digests _____ and _____
Its optimum pH is ___.

A

Endo

glycine, alanine and serine.

proelatase

Trypsin

elastin and collagen.

8

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22
Q

Carboxypeptidase
•It is an ( endo or exo?) peptidase that hydrolyze terminal ( ______ ) peptide bond at the ___ terminus of the polypeptide chain.
•It is secreted in an inactive form called _____.
•It is activated by ____.
•Its optimumpH is ___.

A

Exo

peripheral

carboxyl

procarboxypeptidase

Trypsin

7.4

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23
Q

Intestinal juice

A. Aminopeptidase
•It is an ( endo or exo?) peptidase that acts on the ______ peptide bond at the ___ terminus of the polypeptide chain.
•It releases a single amino acid.

A

Exo

terminal

amino

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24
Q

Tripeptidase
It acts on ______.
It releases _____ and ____

Dipeptidase
It is acts on ______.
It releases _______

A

tripeptides

a single amino acid and dipeptide.

dipeptides
2 amino acids.

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25
Q

Protein Absorption
•it is an (active or passive?) process that needs energy

  • It occurs in ______
  • Absorption of amino acids is rapid in the ________ but slow in the ______
A

Active

small intestine

duodenum and jejunum

ileum.

26
Q

Mechanism of amino acid absorption

There are two mechanism for amino acids absorption.

  1. _______________ system
  2. __________ transport system
A

Carrier proteins transport

Glutathione

27
Q

Pathways for amino acid degradation

In animals, amino acids undergo _________ in three different metabolic circumstances:

  1. During the normal synthesis and degradation of cellular proteins, some amino acids that are released from protein breakdown and are _____________ undergo oxidative degradation.
  2. When a diet is rich in protein and the ingested amino acids __________, the surplus is catabolized
  3. During _________ or ______, when carbohydrates are either unavailable or not properly utilized, cellular proteins are used as ____.
A

oxidative degradation

not needed for new protein synthesis

exceed the body’s needs for protein synthesis

starvation or in uncontrolled diabetes mellitus

Fuel

28
Q

amino acids (can or cannot?) be stored

A

Cannot

29
Q

Reactions amino acids undergo

  1. Transaminations:
    •catalyzed by ______;
    •they are named according to their ______ substrates (ex: glutamate-aspartate aminotransferase).
    •reaction Requires ______ and a _______ (eg ————)
A

aminotransferases

amino acid

an amino acid and a keto acid

alpha keto glutarate

30
Q

Reactions amino acids undergo

  1. Decarboxylation: ____ of _____
  2. Racemization: interconversion of ____ and ___ forms.
  3. _____ and ———-e deamination
  4. ____lization
  5. Elimination and replacement reaction ___-carbon of amino acid
  6. Elimination and replacement reaction __-carbon of amino acid
A

Removal of carbondioxide

L- and D-

Oxidative and non-oxidative

Dealdo

β

Alpha

31
Q

Excretion
There are 3 nitrogen waste excretion products of animals from amino acid degradation.

  • ______
  • 2) ____
  • 3)_______
A

Ammonia (NH3 or NH4+)

UREA

URIC ACID

32
Q
  • Ammonia (NH3 or NH4+).
  • _______ animals simply release it into the surrounding ____ where it gets diluted to non-toxic concentrations. Animals that do this are called ______.
  • 2) UREA
  • Most ______ (especially _____)
  • —called _____.
  • 3) URIC ACID
  • _______ and ______ (the (black or white?) stuff: not very H2O soluble)
  • —called _______.
A

Aquatic

water

AMMONOTELIC

terrestrial vertebrates; mammals; UREOTELIC

Birds & terrestrial reptiles

White; URICOTELIC

33
Q

Neurotransmitters derived from amino acids include

_______, 5-hydroxytryptamine (serotonin), dopamine, norepinephrine, and epinephrine.

A

γ-aminobutyrate

34
Q

Conversion of ______ to Niacin, tryptamine.

Role of ___,______,____,_____ as precursors for synthesis of folic acid and vitamin B12- one carbon metabolism.

A

Tryptophan

glycine, serine, glutamine, methionine

35
Q

Some deficiencies and diseases associated with amino acids metabolism

These are in-born errors caused by blocks in some biochemical pathways due to an (heritable or inheritable?) enzyme deficiency.

  • The blocked amino acid accumulate and may be directed into other pathways which results in the formation of __________
  • The blocked amino acid appear in (little or large?) amounts in the urine of the person with the error.
A

inheritable

deleterious substances.

Large

36
Q

aminoacidurias.

•Two types exist:_______ and _____ aminoacidurais.

A

overflow and renal

37
Q

In overflow aminoacidurias

the plasma level of the amino acid involved is ______ due in part to _______ and the deficiency of ___________

•There such deficiencies like: _________,________,________,_______disease

A

excessively high

over production

metabolizing enzyme.

phenylketonuria, alkaptonuria, homocystinuria and marple syrup urine

38
Q

In renal aminoacidurias

the renal tubules are unable to ________
•
•The amino acids are thus lost in ____.

•The two major deficiency states are _____ and ______ disease.

A

reabsorb some amino acids.

urine

cystinuria and hartnup

39
Q

Phenylketonuria (PKU)
•Here the enzyme __________ is lacking as a result phenylalanine is directed to the production of deleterious acidic substances such as _________

  • Occurs in one of every _____ birth.
  • Clinical manifestation include severe ________,________, and _______
A

phenyl alanine hydroxylase

phenyl lactic acid.

10,000

mental retardation, convulsion and depigmentation (Albinism).

40
Q

the most prevalent of the aminoaciduria is ????

A

Phenylketonuria

41
Q

_____ leads to melanin pigments

A

DOPA

42
Q

Clinical features of PKU

Baby goes from a normal infant to an idiot in _____ - very striking.

Epilepsy and seizures,__-__ months. Stops before ____.

EEG: abnormal pattern; injury in hypothalamus.
Behaviour:
Uncontrollable ___.
_______.
Hyperactive

A

one year

6-18

adulthood

temper

Irritable

43
Q

Sypmtoms of PKU
•_________ odor of urine, which is caused by _______.
•Skin lesions: _____.
•Vomiting.
•Pigmentation: ~60% of patients with PKU are ___ and ___-eyed.

A

Musty (“mousey”) ; phenylpyruvate

eczema

blond and blue

44
Q

Most PKU patients are blond and blue -eyed.

Why??

•The _____ of tyrosine by tyrosinase, which is the first step in formation of the pigment melanin, is ______ inhibited by the high levels of ______ present

A

hydroxylation

competitively

phenylalanine

45
Q

Diagnosis of PKU

In urine: phenylalanine + FeCl3  _________ colour reaction.
Requires high concentrations of ______.

A

olive-green

phenylpyruvate

46
Q

Treatment of PKU
Start as soon as possible!

The earliest treatment is started, the more ______ can be prevented.

Treatment should not be delayed beyond the ______ of life.

A

neurological damage

first month

47
Q

IN PKU patients

Most natural protein contains phe – impossible to satisfy body’s protein without exceeding phe limit…so blood phe is maintained by feeding ______ amino acid preparations (low or high?) in phe.

Some natural foods are used as well that are low in phe: fruits, veggies, certain cereals.

A

synthetic

Low

48
Q

In PKU PATIENTS

Tyrosine supplement: tyrosine is now an ____ amino acid; if low, L-tyrosine supplements are given.
10% of protein prescribed.

A

essential

49
Q

tyrosine supplements alone will prevent mental retardation in classic PKU.

T/F

A

F

tyrosine supplements alone will not prevent mental retardation in classic PKU.

50
Q

In a pku patient, how long should the low phe diet be used for

After ___: development of brain over. Low phe is maintained at least for _____

Continue throughout _____ or ___ to be safe

A

1 year; 4-5 years.

Adolescence

Life

51
Q

Reversal of Biochemical Abnormalities in a pku patient that is under treatment

___ease in concentration of phe metabolites in urine.
____ skin,____ pigment.

Neurological signs: all improved; less restless, pay more attention, EEG normalized.
I.Q. depends on ______

A

Decr

Better

darker

time, age…

52
Q

Maternal PKU

When women with PKU who are not on a low phenylalanine diet become pregnant, the offspring are affected with the “maternal PKU syndrome”: ______,_______,______ abnormalities in the fetus.

These developmental responses occur during the ______ of pregnancy. Thus, dietary control must begin ______

A

microencephaly, mental retardation, and congenital heart

first months

prior to conception

53
Q

Alkaptonuria

  • In this situation, the metabolism of phenylalanine and tyrosine is blocked at the stage of _____________
  • ________ accumulate and appear in urine.
  • The urine ____ on _____
A

homogentisic acid oxidase.

Homogentisic acid

darkens; standing

54
Q

Excessive homogentisic acid causes damage to _____, ______ as well as precipitating as ______

A

cartilage

heart valves

kidney stones.

55
Q

Homocystinuria

  • Here the enzyme ________ is deficient
  • As a result of ____ and its disulphide oxidation product homocystine accumulate and are secreted.
  • This leads to ____ disorder.
  • This also occurs in the absence of another enzyme _______ which breaks ______ to _____
A

cystathione synthetase

homocysteine

skeletal

cystathionase

cystathione to cysteine

56
Q

Homocystinuria

•________+ ____—> Cystathione

____ enzyme is deficient

OR

Cystathione –> -> _______ + ______

_____ enzyme is deficient

A

Homocysteine ; serine

cystathione synthetase*

Homoserine + Cysteine

cystathionase*

57
Q

Maple syrup urine disease
•This disorder involves ______ amino acids (___,____,___)
•The deficient enzyme is branched chain _____ and ________
•______ accumulates causing ____ and mental retardation.
•The disease is manifested by severe brain damage.
•Urine smells like ____.
•Few infants survive beyond the _____ of life

A

branched chain

valine, leucine, isoleucine

ketodecarboxylase and ketodehyrogenase.

Keto acids; ketosis

maple syrup

first year

58
Q

Renal aminoacidurias

Cystinuria: the amino acid involved are the ___ amino acids- ____,____,____,____

These are thought to possess a common _______ in the renal tubules.

Failure of the transport system results in cystinuria.

Clinical effect includes ______ due mainly to presence of ____ which is very (soluble or insoluble?) at urine pH.

A

basic

cysteine, ornithine, arginine and lysine (COAL).

transport membrane protein

renal calculi

cystine

Insoluble

59
Q

Hartnup’s disease:

This is due to the inability of the renal tubules to absorb ______ with the exception of ___.
Clinical feature include pellagra (rough skin) due to loss of ______ in urine.

A

all other amino acids

COAL

tryptophan

60
Q

Amino acid transport disorders

———-
______
______

A

Cystinuria
Dicarboxylic aminoaciduria
Hartnup disease

Bch 201 (11 decks)

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