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Biochemistry 2019 > Lecture 32 > Flashcards

Lecture 32 Flashcards

1
Q

State the synthesis precursors (intermediate molecules) from the following pathways, that are used to synthesize AAs

Glycolysis: (3)

TCA Cycle: (2)

Pentose Phosphate Pathway: (2)

A

Glycolysis:
3-phosphoglycerate
PEP (Phosphoenol pyruvate)
Pyruvate

TCA Cycle:
Alpha-ketoglutarate
OAA

Pentose Phosphate Pathway:
Ribose-5-phosphate
Erythrose-5-phosphate

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2
Q

State the Essential AAs

A 
Phenylalanine
Valine
Threonine
Tryptophan
Isoleucine
Methionine
Histidine
Arginine
Leucine
Lysine
("PVT TIM HALL" mnemonic)
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3
Q

State the 3 Transamination reactions that occur via a pyridoxal phosphate-dependent (vitamine B12) reaction (enzyme, reactant, product)

A
  1. SGPT makes Pyruvate become Alanine
  2. SGOT makes OAA become Aspartate
  3. Glutamate Dehydrogenase makes Alpha-ketoglutarate become Glutamate
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4
Q

Once SGOT creates Aspartate from OAA, what 4 AA’s can it become and state the type of reactions it takes to create these

A
  1. Aspartate to Asparagine when Glutamine donates an NH3 group
  2. Aspartate to Lysine, Methionine, or Threonine (humans cannot conduct this reaction, therefore these AA’s are essential AAs)
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5
Q

Between Synthetases and Synthases, which uses ATP?

A

Synthetases

has an extra “T” bc it uses A”T”P

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6
Q

How is glutamine formed? why is it formed?

A

Glutamate has an NH3+ group put on it to form Glutamine

Glutamine is used to transport free NH4+ to the liver to eventually be excreted

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7
Q

Compare the Adenylation and Uridylylation in terms of their definitions. What does Adenylation inactivate?

A

Adenylation: the addition of an AMP ribonucleotide
Inactivates Glutamine Synthetase

Uridylylation: the addition of a UMP ribonucleotide

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8
Q

Describe what causes the feedback inhibition and feedforward activation that occurs in order to regulate the Uridylylation that PII conducts

A

Feedback Inhibition: Glutamine maintains PII in it’s inhibitory form (-UMP)

Feedforward Activation: Alpha-ketoglutarate + ATP maintain PII in its active form (+UMP)

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9
Q

Besides receiving another NH3+ group and becoming Glutamine, describe the other 2 possible “fates” of Glutamate. (include the type of reactions that carry out these fates)

A
  1. Forms Proline after several reductions and cyclizations

2. Forms Ornithine after 1 reduction and a transamination

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10
Q

Ornithine is ______ minus urea.

A

Arginine

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11
Q

What are the 3 AA derivatives of 3-Phosphoglycerate that can be formed?

A
  1. Serine
  2. Glycine (via removal of Serine’s side chain)
  3. Cysteine (via a homocysteine intermediated formed from Serine)
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12
Q

Tyrosine is a ______intermediate of ______. (catabolic or anabolic? ; AA for 2nd blank)

A

Catabolic

Phenylalanine

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13
Q

Aromatic AAs are synthesized from intermediates from what cellular pathway?

A

The Pentose Phosphate Pathway

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14
Q

Which aromatic AA is synthesized directly from Ribose-5-phosphate?

A

Histidine

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15
Q

State the 2 reactants that combine to form Chorismate. Also state the 3 possible aromatic AA’s that are formed using precursors from both the Pentose Phosphate Pathway and Glycolysis.

A

Erythrose-4-Phosphate + PEP = Chorismate

This forms Tryptophan, Phenylalanine, or Tyrosine

(this reactions occurs in plants/fungi NOT humans so these are essential AAs)

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16
Q

What 3 AA’s are synthesized from Pyruvate, exist ONLY to be incorporated into proteins, and have their synthesis regulated by feedback inhibition?

A

Valine, Leucine, and Isoleucine

“LIV” mnemonic ; the guys LIV to be part of proteins

17
Q

State the 2 “Central AA’s”.

A

Glycine and Serine

18
Q

Heme is a derivative of what AA? What conversion must occur prior to heme assemble?

A

Glycine

Acetate must be converted to Succinyl-CoA (prior to synthesizing heme)

19
Q

Briefly describe what a Porphyria is. Compare the symptoms of a porphyria due to a liver enzyme issue and a Non-liver enzyme issue

A

Porphyria: Deficiency in heme synthesis

Liver Enzyme Deficiency (Porphyria): Pain and Cardiac Dysfunction

Kidney Enzyme Deficiency (Porphyria): Light sensitivity and Altered skin pigmentation

20
Q

Explain why bruises change color over time

A

The Pie-Orbitals in the molecular structure of different substances absorb photons differently, giving off different colors

ex. Heme (purple) to Biliverdin (green) to Bilirubin (yellow) to
Stercobilin (brown) in feces
OR
Urobilin (yellow) in urine

21
Q

Glutathione, Polyamines, and GABA are all derivatives of what AA? Briefly describe each of these

A

All derivatives of Glutamate

Glutathione: an antioxidant

Polyamines: Stabilize DNA (using their positive charges)

GABA: an inhibitory neurotransmitter

22
Q

NO and Creatine Phosphate are both derivatives of what AA? Briefly describe both of these.

A

Arginine Derivatives

NO: a free radical that has 3 isozymes (cardiac signalling, Neuronal, and Immune cell)

Creatine Phosphate: a molecule created in the liver from Creatine that releases almost as much energy when hydrolyzed as the hydrolyzation of ATP
(uses a lot of SAM)

23
Q

SAM is a derivative of what AA? what is the role of sam?

A

Methionine

SAM: primary methyl donor in cells

24
Q

Histamine is a derivative of what AA? what does function does Histamine have in the body?

A

Histidine

Histamine is inflammatory, promotes secretion of HCl and Pepsin in the stomach, and is a neurotransmitter

25
Q

Serotonin is a derivative of what AA? what other “light-dark cycle regulator” molecule is created using Serotonin as a precursor?

A

Tryptophan

Serotonin is a precursor for melatonin

26
Q

What molecule is a known vasoconstrictor, causes smooth muscle to contract around ingested food, and can result in the rapid ejection of toxins from the body (at either end).

A

Serotonin

27
Q

Epinephrine and Dopamine are derivatives of what AA? what important neurotransmitter is a precursor molecule for Epinephrine? (has just 1 more hydroxyl group than Epinephrine.

A

Tyrosine

Norepinephrine is a precursor for Epinephrine

28
Q

L-dopa is a molecule that is derived from what AA? Describe L-dopa’s relationship with Dopaquinone

A

Tyrosine

L-dopa is modified by Tyrosinase to become Dopaquinone

29
Q

Albinism is a deficiency in what enzyme? Compare the different melanins in people with dark and light hair.

A

Albinism: deficiency in Tyrosinase

Dark Hair = Eumelanins > Pheomelanins
Light Hair = Eumelanins < Pheomelanins

(“EU” have dark hair and “PHillip” has light hair mnemonic)

Biochemistry 2019 (32 decks)

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