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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
What is the primary role of carnitine?
transport acyl groups across the inner mitochondrial membrane Transport FA from cytosol to mitochondria for beta ox
26
What AAs carry nitrogen to liver for glycogen or FA synthesis in post absorb state?
Alanine and glutamine
27
How does phenylalanine enter the TCA cycle?
As fumarate | phenylalanine --> tyrosine --> fumarate
28
What AA can fix ammonia?
Glutamate transport and store ammonia in non toxic form - alpha keto glutamate + ammonia --> glutamate via glutamate dehydrogenase - also via CPS1 or glutamate synthase
29
What is homocystunuria?
Defect in cystathionine b synthase resulting in buildiup of methionine because homocysteine remethylated instead of being converted to cystathionine
30
What pathway is HGRPT used in?
Salvage pathway for purines | Catalyzes free base (guanine or hypoxanthine) to nucleotide (IMP or GMP)
31
What type of nucleic acid is most likeyl to contain post transcriptionally modified bases?
tRNA | examples: pseudoruidine and ribothymine
32
What does diptheria do?
Inhibit eEF-2 in eukaryotes which blocks translocation of peptidyl-tRNA during translation Covalent attachment of ADP to catalytic unit of EF
33
What is pyrimidine deamination?
C replaced with Uracil | Corrected by replacing U with thymidine so binding A instead of G
34
What does tetracycline do?
Bind to 30s blocking access of amnio acyl tRNA to A site
35
What happens when Na+/K+ ATPase is permanently open
Na+ and Ca++ elevated in cytosol K+ reduced in cytosol Normal function= low intra cellular Na+ and high K+
36
What is the mechanism of cholera?
ADP ribosylation of alpha subunit of Gs so constantly stimulating production of cAMP by adenylate toxin
37
How many high energy phosphates are generated through complete metabolism of one acetyl CoA molecule to CO2 and H2O
``` 12: 9 ATP 3 from NADH 2 from FADH2 1 from GTP ```
38
What is the glycerophophate shuttle?
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
How does UCP1 increase energy expenditure?
Brown adipose Binds proton on the outer side of the inner mitochondrial membrane and then facilitates release into matrix generating heat
40
What is the rate limiting step of gluconeogenesis?
Fructose 1,6BP +H2O -> furctose 6-P + Pi
41
What do CPSI and AST do?
convert amino acid nitrogen into two compounds that directly provide urea introgen AST= aspartate CPSi= RL of urea, incorporate nitrogen into urea
42
What does the utilization of ammonia for the synthesis of alpha amino acids rely on?
Glutumate dehydrogenase: fixes ammonium into alphas ketogluturate generating glutamate NH4+ + alpha ketogluturate +NAD+ --> glutumate +NADH which can undergo transamination
43
What are the basic AAs?
Arginine, histidine, and lysine | compete for same transport mechanism
44
What is hartnup?
Can't absorb neutral AAs like tryptophan so can synthesize NAD+ and NADP
45
What is found exclusively in the inner leaflet?
Phophatidylserine | goes to outer leaflet to mark cell for apoptosis
46
What are P-type ATPases?
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
Optimal function of metalloenzymes is dependent on the participation of the metal cofactor in what?
Stable coordination of active site residues | Metal ions function as cofactors by associating with enzymes via noncovalent interactions
48
What is the equation for osmolality?
2Na + glu/18 + BUN/2.8
49
Where are Branched chain amino acids originally synthesized?
In the muscle, high concentration of branched-chain amino acid transferase
50
How are deoxyribonucleotides synthesized?
Synthesized from ribonuleotides by an enzyme system involving thioredoxin which is used by nucleoside diphosphate reductase as a hydrogen-electron donor
51
How does dietary uridine which reverses anemia and decrease orotic acid formation in people with orotic aciduria work?
Converts exogenous uridine to UMP by uridine phophotransferase, UTP then used as substrate for CTP Inhibits CPSII by UTP
52
What are some defining characterisitics of pyrimdine synthesis de novo?
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
What glucose transporter is mainly in the liver?
GLUT2 | Located on apical membrane noves Glc, Cal, and Fru through facilitated diffusion
54
What is the rate limiting step of the urea cycle?
mitochondrial CPS-1 | Nitrogen atom of resulting carbamoyl phosphate incorporated into urea
55
What is the rating limiting step of fatty acid synthesis?
Acetyl CoA carboxylase results in the formation of malonyl CoA
56
How does insulin effect glucose uptake? glycogen breakdown? FA synthesis? Glycogen synth? PFK activity?
``` Increase Decrease Increase Increase Increase ```
57
What favors the active from of Pyruvate Dehydrogenase Complex?
Low Ca2+ Acetyl CoA High levels of pyruvate High NADH/NAD+
58
How is the TCA cycle stimulated during exercise?
stimulation of the flux through a number of enzymes by a decreased NADH/NAD+ ratio
59
What would you expect in a patient with an OxPhos disease?
High NADH/NAD+ ratio in the mitochondria
60
What acid base imbalance will your patient present with if kidneys can't reabsorb HCO3 from blos stream?
Metabolic acidosis
61
The elongation of FA chain require what molecule as reducing power? Where does it come from?
NADPH | PPP
62
What step of the urea cycle takes place in the mitochondria?
Formation of citrulline from ornithine and Carbamoyl-P
63
What do adipocytes use for energy?
glucose and FAs not AAs
64
What bond does cellulose have?
beta 1-4
65
What does a deficiency in fumarase cause?
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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