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SFM Final Lectures > Biochem review Panini and BRS > Flashcards

Biochem review Panini and BRS Flashcards

1
Q

What does a positive nitrogen balance mean?

A

Dietary nitrogen&raquo_space; excreted nitrogen

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2
Q

What type of cells does Pyruvate Kinase deficiency effect? What does this enzyme catalyze?

A

Erythrocytes because primarily use glucose for energy, causes cell membrane alterations and splenic sequestration

When phosphorylated pyruvate kinase is inactive

Last step of glycolysis PEP +ADP –> pyruvate +ATP

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3
Q

Why is the NADH/NAD+ ratio during high lactate states?

A

NADH has been generated by glyceraldehye-3-phopshate dehydrogenase reaction and NAD+ needs to be regenerated under anaerobic conditions

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4
Q

What complex does cyanide and carbon monoxide bind to?

A

Complex IV= cytochrome oxidase

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5
Q

What reaction does pyruvate carboxylase catalyze?

A

Pyruvate –> OAA leading to anaerobic metabolism
Deficiency causes lactic acid buildup
Need Biotin as cofactor

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6
Q

What is Type I GSD? What enzyme is deficient?

A

von Gierke
Glucose-6-phosphatase
Can’t release glucose into bloodstream

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7
Q

What is Type II GSD? What enzyme is deficient?

A

Pompe
Acid maltase= alpha 1,4 glucosidase
Heart pump
Loss of a lysosomal glucosidase activity

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8
Q

What is Type III GSD? What enzyme is deficient?

A

Cori
Glycogen debranching enzyme
Indicator is presence of dextrin

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9
Q

What is Type IV GSD? What enzyme is deficient?

A

Anderson
glucose 4:6 transferase
liver cirrhosis

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10
Q

What is Type V GSD? What enzyme is deficient?

A

McArdle

Muscle glycogen phosphorylase : muscle cramps

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11
Q

Where is glucose-6-phosphatase expressed?

A

Liver and kidneys are the only 2 organs with the enzymes necessary for gluconeogenesis

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12
Q

What inhibits fructose 1,6 biphosphatase?

A

fructose 2,6 biphosphatase and AMP

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13
Q

What enzyme is deficient in classical galactose in comparison to non classical?

A

Classical= Galactose 1 phosphate uridyltansferase

Non classical= glacktokinase

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14
Q

What reaction is liver specific for triglyceride synthesis?

A

Glycerol –> glycerol 3 phosphate via ATP and glycerol kinase

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15
Q

What would cause a high level of excreted orotic acid?

A

Defect in prymidine synthesis

Orotic acid not converted to OMP –> UMP causing orotic aciduria

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16
Q

What type of transport mechanism does glucose use for gastrointestinal absorption?

A

Active and facilitated via SGLT2

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17
Q

What tissues use GLUT4 for glucose transport?

A

Muscle and Fat

insulin dependent transporter

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18
Q

What happens when pyruvate dehydrogenase is inhibited?

A

Reduced flux of carbon in TCA cycle because pyruvate not converted to OAA and acetyl CoA

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19
Q

What does fructose 2,6 bisphosphatase stimulate?

A

Glycolysis via PFK1

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20
Q

What does arsenic bind?

A 
Lipoic acid (has 2 close SH groups) which is a cofactor of pyruvate dehydrogenase (also use thiamine/TPP)
If inhibited then instead of entering TCA pyruvate converted to lactate
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21
Q

If a cell had a non functional mitochondria how many moles of ATP would be produced from 1 mol glucose?

A

2 ATPs

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22
Q

What feeds electrons into complex II?

A

Succinate

Succinate –> fumarate succinate dehydrogenase uses FAD+ as co-substrate

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23
Q

What happens when you have a G6PDH deficiency?

A

NADH levels drop so you cannot produce glutathione which normally protects from ROS –> hemolysis

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24
Q

Where are VLCFAs oxidized? What does this process produce?

A

Peroxisomes

Generates H2O2, NADH, and acetyl CoA

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25
Q

What is the primary role of carnitine?

A

transport acyl groups across the inner mitochondrial membrane
Transport FA from cytosol to mitochondria for beta ox

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26
Q

What AAs carry nitrogen to liver for glycogen or FA synthesis in post absorb state?

A

Alanine and glutamine

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27
Q

How does phenylalanine enter the TCA cycle?

A

As fumarate

phenylalanine –> tyrosine –> fumarate

28
Q

What AA can fix ammonia?

A

Glutamate transport and store ammonia in non toxic form

  • alpha keto glutamate + ammonia –> glutamate via glutamate dehydrogenase
  • also via CPS1 or glutamate synthase
29
Q

What is homocystunuria?

A

Defect in cystathionine b synthase resulting in buildiup of methionine because homocysteine remethylated instead of being converted to cystathionine

30
Q

What pathway is HGRPT used in?

A

Salvage pathway for purines

Catalyzes free base (guanine or hypoxanthine) to nucleotide (IMP or GMP)

31
Q

What type of nucleic acid is most likeyl to contain post transcriptionally modified bases?

A

tRNA

examples: pseudoruidine and ribothymine

32
Q

What does diptheria do?

A

Inhibit eEF-2 in eukaryotes which blocks translocation of peptidyl-tRNA during translation
Covalent attachment of ADP to catalytic unit of EF

33
Q

What is pyrimidine deamination?

A

C replaced with Uracil

Corrected by replacing U with thymidine so binding A instead of G

34
Q

What does tetracycline do?

A

Bind to 30s blocking access of amnio acyl tRNA to A site

35
Q

What happens when Na+/K+ ATPase is permanently open

A

Na+ and Ca++ elevated in cytosol
K+ reduced in cytosol
Normal function= low intra cellular Na+ and high K+

36
Q

What is the mechanism of cholera?

A

ADP ribosylation of alpha subunit of Gs so constantly stimulating production of cAMP by adenylate toxin

37
Q

How many high energy phosphates are generated through complete metabolism of one acetyl CoA molecule to CO2 and H2O

A 
12: 
9 ATP
3 from NADH
2 from FADH2
1 from GTP
38
Q

What is the glycerophophate shuttle?

A

NADH reduces dihydroxyacetone phosphate to glycerol phosphate which can pass through the outer mitochondrial membrane to be reoxidzied
How NADH in cytoplasm can pass electrons via ETC

39
Q

How does UCP1 increase energy expenditure?

A

Brown adipose
Binds proton on the outer side of the inner mitochondrial membrane and then facilitates release into matrix generating heat

40
Q

What is the rate limiting step of gluconeogenesis?

A

Fructose 1,6BP +H2O -> furctose 6-P + Pi

41
Q

What do CPSI and AST do?

A

convert amino acid nitrogen into two compounds that directly provide urea introgen
AST= aspartate
CPSi= RL of urea, incorporate nitrogen into urea

42
Q

What does the utilization of ammonia for the synthesis of alpha amino acids rely on?

A

Glutumate dehydrogenase: fixes ammonium into alphas ketogluturate generating glutamate
NH4+ + alpha ketogluturate +NAD+ –> glutumate +NADH which can undergo transamination

43
Q

What are the basic AAs?

A

Arginine, histidine, and lysine

compete for same transport mechanism

44
Q

What is hartnup?

A

Can’t absorb neutral AAs like tryptophan so can synthesize NAD+ and NADP

45
Q

What is found exclusively in the inner leaflet?

A

Phophatidylserine

goes to outer leaflet to mark cell for apoptosis

46
Q

What are P-type ATPases?

A

Characterized by formation of E=P intermediate followed by dephosphorylation removing Pi from enzymes.
Amino acid aspartate serves as the site for the phosphorylation step

47
Q

Optimal function of metalloenzymes is dependent on the participation of the metal cofactor in what?

A

Stable coordination of active site residues

Metal ions function as cofactors by associating with enzymes via noncovalent interactions

48
Q

What is the equation for osmolality?

A

2Na + glu/18 + BUN/2.8

49
Q

Where are Branched chain amino acids originally synthesized?

A

In the muscle, high concentration of branched-chain amino acid transferase

50
Q

How are deoxyribonucleotides synthesized?

A

Synthesized from ribonuleotides by an enzyme system involving thioredoxin which is used by nucleoside diphosphate reductase as a hydrogen-electron donor

51
Q

How does dietary uridine which reverses anemia and decrease orotic acid formation in people with orotic aciduria work?

A

Converts exogenous uridine to UMP by uridine phophotransferase, UTP then used as substrate for CTP
Inhibits CPSII by UTP

52
Q

What are some defining characterisitics of pyrimdine synthesis de novo?

A

A free base is formed first and then the ribose sugar is added
One step occurs in the mitochondria
OMP –> UMP –> CTP is the sequential process
Rate limiting step catalyzed by CPS II

53
Q

What glucose transporter is mainly in the liver?

A

GLUT2

Located on apical membrane noves Glc, Cal, and Fru through facilitated diffusion

54
Q

What is the rate limiting step of the urea cycle?

A

mitochondrial CPS-1

Nitrogen atom of resulting carbamoyl phosphate incorporated into urea

55
Q

What is the rating limiting step of fatty acid synthesis?

A

Acetyl CoA carboxylase results in the formation of malonyl CoA

56
Q

How does insulin effect glucose uptake? glycogen breakdown? FA synthesis? Glycogen synth? PFK activity?

A 
Increase
Decrease
Increase 
Increase 
Increase
57
Q

What favors the active from of Pyruvate Dehydrogenase Complex?

A

Low Ca2+
Acetyl CoA
High levels of pyruvate
High NADH/NAD+

58
Q

How is the TCA cycle stimulated during exercise?

A

stimulation of the flux through a number of enzymes by a decreased NADH/NAD+ ratio

59
Q

What would you expect in a patient with an OxPhos disease?

A

High NADH/NAD+ ratio in the mitochondria

60
Q

What acid base imbalance will your patient present with if kidneys can’t reabsorb HCO3 from blos stream?

A

Metabolic acidosis

61
Q

The elongation of FA chain require what molecule as reducing power? Where does it come from?

A

NADPH

PPP

62
Q

What step of the urea cycle takes place in the mitochondria?

A

Formation of citrulline from ornithine and Carbamoyl-P

63
Q

What do adipocytes use for energy?

A

glucose and FAs not AAs

64
Q

What bond does cellulose have?

A

beta 1-4

65
Q

What does a deficiency in fumarase cause?

A

TCA cycle intermediates elevated in urine
Small head
Hypotonia, spasticity, and developmental delay, episodes of acute metabolic acidosis

SFM Final Lectures (7 decks)

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