2.1.1 Metabolism II Flashcards

1
Q

Disorder associated with a defect in glycine and imino amino acid transport?

A

Joseph’s syndrome or glycinuria

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2
Q

What reactions are mediated by the enzyme serine-threonine dehydratase?

A
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3
Q

Describe the arginine metabolism pathway from arginine to L-glutamate

A
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4
Q

Classify the amino acids into three groups: glucogenic (make glucose), ketogenic, and both glucogenic and ketogenic.

A

Memorize the only ketogenic: Leu, Lys

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5
Q

Cytosolic protein turnover (non-lysosomal) characteristics

A
  1. pH near neutrality
  2. proteases with optimal pH around 7
  3. Cytosolic proteases are metal requiring
  4. Proteins are marked with ubiquitin
  5. Ubiquitin tagged proteins are attacked by proteosome complexes
  6. Proteosomes with high molecular weight (1500 KDa)
  7. Ubiquitin covalently modifies lysine residues
  8. Ubiquitin plays other roles in cellular signaling
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6
Q

Name 4 enzymes that are used in breaking down proteins. (and where they are found)

A

Carboxyl protease: pepsin (stomach)

Serine proteases: trypsin, chymotrypsin, elastase (pancreatic secretion)

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7
Q

State the important transporters involved in the absorption of amino acids.

A

Apical: Na + Amino acid symporter

Basal: Na-K ATPase, amino acid channel

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8
Q

Name the 6 characteristics of lysosomal degradation in protein turnover

A
  1. lysosomal pH b/t 4 and 5
  2. variety of proteases with pH optima in this range
  3. lysosomal porteases act on proteins which are taken up via endocytosis from outside the cell or cell surface (surface receptor)
  4. The process of endocytosis yields endosomes which fuse with proteosomes which allows for breakdown
  5. Capable of breaking down proteins all the way to free amino acids
  6. Use the mannose-6-phosphate marker
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9
Q

What are some of the metabolic intermediates derived from the carbon skeletons of amino acids?

A

pyruvate, acetoacetyl CoA, acetyl CoA, alpha-ketoglutarate, succinyl CoA, fumarate, oxaloacetate

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10
Q

What are some ways that nitrogen is excreted?

A

Urea (30g, 86%), ammonium ion, creatine, uric acid

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11
Q

What enzyme is implicated in schizophrenia?

A

D-amino acid oxidase

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12
Q

Where are polyamines important in the body?

A

Polyamines are important in the nucleus, as they are used to neutralize the negative charges of nucleic acid

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13
Q

Most amino acids are converted to what two molecules?

A

Alpha-ketoglutarate and glutamate

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14
Q

The 3 characteristics of AA catbolism (portal/liver)

A
  1. After absorption across the gut the AAs are carried to liver via the portal system
  2. the liver is principal site of both carbon skeleton and nitrogen metabolism and most active organ in synthesis and catabolism
  3. most nitrogen is removed from the AAs by ezymes which either transaminate or alternatively remove the nitrogen to produce NH3
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15
Q

Describe how glucose can be formed from the citric acid cycle

A
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16
Q

A deficiency in what ezyme that mediates the conversion of phenylalanine to tyrosine is indicated in PKU?

A

Phenylalanine hydroxylase

17
Q

Name the vitamin derived cofactor that plays an important role in amino acid and nitrogen metabolism

A

Pyridoxal phosphate

18
Q

Protein is used as energy storage. How much energy is stored as protein?

A

6000 g

24000 kcal

19
Q

How can arginine be used to synthesize nitric oxide?

A
20
Q

Disorders associated with a defect in dibasic amino acid transport?

A

cystinuria or dibasic aciduria

21
Q

Proteins can be broken down into amino acids. Amino acids can be catabolized into what molecules that feeds into the citric acid cycle?

A

Acetyl-CoA

22
Q

Disorder associated with a defect in dicarboxylic amino acid transport?

A

dicarboxylic aciduria

23
Q

Name the 4 different transporter mechanisms, the proteins they move, and diseases associated with a defect in this transport mechanism.

A

Neutral, Dibasic, Dicarboxylic, Glycine and imino

24
Q

Describe the pathway that yields cystine from methionine?

A
25
Q

Describe the various pathways involved in polyamine synthesis.

A
26
Q

What sources as the main source of energy storage?

A

Triacyl glycerol

27
Q

Describe how proteins are broken down and what they yield?

A
28
Q

High levels of what intermediate of amino acid breakdown is associated with cardiovascular issues?

A

Homocysteine

29
Q

Name the 5 inborn errors in amino acid metabolism.

A
30
Q

What organisms convert N2 into NH3?

A

Nitrogen fixing bacteria

31
Q

The inborn error in amino acid metabolism that is associated with inappropriate handling of tryptophan, alanine, (etc. neutral amino acids)

A
32
Q

Disorder associated with a defect in neutral amino acid transport?

A

Hartnup dz

33
Q

What oxidative deamination reaction is mediated by L-amino acid oxidase?

A
34
Q

Describe the three step process used to degrade branched chain amino acids to acetyl CoA.

A
  1. Transaminination -> 2-ketoglutarate
  2. Oxidative decarboxylation
  3. Dehydrogenation/etc.
35
Q

Describe the enzymes used in propionate metabolim

A
36
Q

Name the essential amino acids in adult humans.

A

Human infants and children need additional histidine and arginine during growth and recovery

37
Q

What reaction is mediated by glutamate dehydrogenase?

A

NH4 + alpha-ketoglutarate <–> glutamate