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Biochemistry > Aa metabolism > Flashcards

Aa metabolism Flashcards

1
Q

Carbon Chains Enter Metabolic Pathways

A

Glucogenic= feed into glycoclysis & Krebs

  • pyruvate= ala, cys, gly, ser, met
  • Oxaloacetate= asp, asn
  • a ketoglutarate= arg, glu, gln, his, pro
  • succinyl coA= met, val
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2
Q

Carbon Chains Enter Metabolic Pathways

A

Ketogenic- produce acetyl Co A

  • leu & lys
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3
Q

Carbon Chain enter Metabolic Pathways

A

Both

Produce precursors of gluconeogensis & ketone boides

Ile, Phe, tyr, trp, thr

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4
Q

Low Carb/ High Protein & Fat Diet

A

Glucose essential for brain!

Breakdown protein to supply gluc

Ketone bodies from ketogenic & mixed glucogeneic/ketogenic aa= acidosis

Diuresis= loss of H2O & minerals

Can get shock, coma, death

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5
Q

Problems with Diet

A

Not permanent

Lose lean body mass for gluconeogenesis

Low gluc with higher calorie diet= slower weight loss

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6
Q

Glucose: Pyruvate Transaminase GPT

or

Alanine aminotransferase ALT

A

Cytosolic

Released after minor damage to hepatocytes

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7
Q

Glutamate: Oxaloacetate Aminotransferase GOT

or

aspertate aminotransferase AST

A

in heart & skeletal m., liver

Diagnostic purposes

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8
Q

Acute lymphoblastic luekemia ALL

A

All cells express little Asn synthase but need Asn for nt syn

Injection of asparginase destroys Asn in blood

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9
Q

Folate

A
  • Essential nutrient, Vit M
  • Dihydrofolate reductase converts dietary folate into THF
  • THF used as carrier of C1 bodies in metabolism
  • C1 bodies come from aa metabolism & needed for nt syn!
  • All C1 conversion rxns are reversible!
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10
Q

Sulfphonamides

A
  • Broad spectrum antibiotic
  • pro drug gets converted to sulfanilamide in body
  • Sulfanilamide has no effect on human folate metabolism but stops bac from syn it
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11
Q

Trimethoprim

A
  • inhibits dihydrofolate reductase- enz converts folate into THF
  • Drug given w/ sulphonamide
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12
Q

Methotrexate MTX

A
  • inhibitor of dihydrofolate reductase
  • works on mammals
  • Treats cancer & in lower doses- autoimmune disease
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13
Q

Ala & Ser cycle

A

Exertion= lactic acid production & NH4+

Detox in liver

Form ala to transport both products in blood w/o toxicity

Ser can convert to pyruvate

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14
Q

Glu, Gln, Asp & Asn

A

Enter Krebs

Glu & Asp produce Gln & Asn by carboxylic amidation

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15
Q

Gly, Thr & Ser

A

Irreversible rxns

Glycine cleavage enz def= non ketotic hyperglycinemia.

  • AR
  • severe neuronal def, can be fatal.

Excess glycine conversion= oxalate (forms kidney stones)

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16
Q

Met & Cys

A

Met makes SAM (C1 carrier)

If not enough folate, homocysteine accumulate leading to vascular complications.

  • more homocysteine than needs to be converted to Met, condensed to cystathionine.
  • Cystathionine synthase- defect AR leads to homocysteinuria.

Excess folate can maks pernicious anemial from B12 def but neurological iplication still present!

17
Q

Homocysteine–> Met need B12!

A

Met syntahse needed for regen of folate & met. If both supplied, megaloblastic anemia & choline syn defect won’t occur. Only problem= homocysteinuria.
Methylmalonyl co A mutase blocked, methylmalonic acid used for FA instead of malonic acid= myelin destabilization. Need B12 for odd chain FA metabolism.

18
Q

Homocystenuria

A

mental retardation,

eye lens dislocation,

bone elongation,

osteoprosis,

thrombosis!

Treat- mega dose of B6

19
Q

Val, Ile & Leu

A

Defect in a ketoacid dehydrogenase branched chain

  • maple syrup urine disease- caused by sotolone
  • AR, severe mental def, optic atrophy, ataxia, fatigue, acidosis metabolic, ADHS, axial, hypotonia, hypoglycemia, exertional fatigue, high liver enz & aa branched in serum
  • Death

Val & Ile Propionyl coA; Leu HMG- Co A

If propionyl co A converted to succinyl co A defect in methylmalonic aciduria

  • FA & aa metabolism
20
Q

Phe & Tyr

A

Phe converted to Tyr

PKU

  • inherited rec defect in phenylalanine hydroxylase or dihydrobiopterine reductase (Phe to Tyr)
  • seizures, spasticity, irreversible brain damage
  • No Phe until adolescence!
  • mandatory diaper test
  • More common in UK than Japan

Dihyrobiopterine reductase defect

  • problems w/ L DOPA production & 5 OH Trp.
  • SE & catecholamine production issues.
21
Q

Occulocutaneous albinism

A

syn of melanin & red hair pigment defective.

Get sun burnt very easily

Defects melanin (one of products of Tyr)

22
Q

Vitiligo

A

Patchy, de pigmented skin .

Auto immune to melanocytes

23
Q

Tyrosinemia

A

Tyrosinemia type I

  • def in fumarylacetoacetate hydrolase (when tyr gets broken down to fumarate in series rxn)
  • cabbage like urine smell
  • Quebec

Type II

  • tyrosine aminotransferase def
  • damage brain, eyes & skin

Type III

  • hydroxyphenyl pyruvate oxidase defect
  • mild mental def & ataxia
  • Hawkinsinuria- enz w/ reactive intermed. Produce hawkinsine.
  • ADominant, acidemia only in 1st year of life (restrict phe & tyr)
  • Hawkinsin= Cl- smell to urine.
24
Q

Alkaptonuria

A

Benign, AR

Homogentisate oxidase def

Product excreted in urine, dark pigment when exposed to air.

Arthritis

Accumulates in tissues as ochronosis *related to tyr converted to fumarate pathway*

25
Q

Trp & Lys

A

Xantenurate & kynurenate products from catabolism of Trp, give urine its yellow color

Trp converted to nicotinamide

some lys converted to trp

Lys degradation:

  • Hyperlysinemia/uria- impaired sex dev, weakness, normocytic, normochromic anemia

Excess lys

  • competitive I of arginase
  • hyperammonemia
26
Q

Pro Arg His & ornithine

A

Catabolize to Glu & enter KREBS

Pro- collagen, antiox conversion of Pro to Glu yeilds NADH & FADH

  • Cutix laxa- wrinkeled skin, mental retardation, cataract, hypoprolinemai,
  • P5CS- def to make proline, hypereleastic skin, joint laxity, B/L cataract, neurodegen, hypoprolinemia, temporal urea cycle def

Excess Arg converted to ornithine & then to Glu

His to Glu not reversible

  • carnosine can maks His def
  • Histidinemia- def in his-ase, gives + diper test like for PKU
  • Habitual FIGLU excretion- enz catalyzing last step defective, appears in urine.
27
Q

Polyamines

A

Syn by decarbox of Lys (cadaverine) or ornithine (putrescine etc.)

Help DNA packing

Reg NMDA & AMPA

Inhibition w/ difluoromethylornithine= treat cancer & Trypanosoma brucei (sleeping sickness.

Biochemistry (8 decks)

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