USMLE: Biochem Buzzwords Exam
Questions With 100% Solved Correct
Answers Latest Update
What are the three posttranscriptional modifications? - ANSWER✔✔-1. 7-methyl
guanine cap on the 5' end
2. Addition of the poly(A) tail to the 3' end
3. Removal of introns
What AA is the major carrier of nitrogen byproducts from most tissues in the body? -
ANSWER✔✔-Glutamine
What two AAs have a pKa of 4? - ANSWER✔✔-Aspartic acid and glutamic acid
How many acetyl CoAs per glucose enter into the TCA cycle? - ANSWER✔✔-2 acetyl
CoA per glucose, producing 12 ATPs per acetyl CoA, resulting in a total 24 ATPs
produced from glucose (via acetyl CoA) enter the TCA cycle
COPYRIGHT © 2025 BY OLIVIA GREENWAYS, ALL RIGHTS RESERVED 1
,What topoisomerase makes ssDNA cuts, requires no ATP, relaxes supercoils (only
negative in prokaryotes, both for eukaryotes), and acts as the swivel in front of the
replication fork? - ANSWER✔✔-*Topoisomerase I (Relaxase)*
- what drugs inhibit this?
Autoantibodies targeted against type I topoisomerase are called anti-Scl-70 antibodies,
named by the association with scleroderma
-Drugs which poison Eukaryotic Topo I e.g. camptothecin, Topotecan
In Prokaryotes, what is the name of the RNA sequence that ribosomes bind to so
translation can occur? - ANSWER✔✔-Shine-Dalgarno sequence
Name the pattern of genetic transmission: both M and F are affected; M-to-M
transmission may be present; both parents must be carriers; the trait skips generations;
two mutant alleles are needed for disease; and affected children may be born of
unaffected adults? - ANSWER✔✔-Autosomal recessive
What factors are needed for translation in prokaryotes? - ANSWER✔✔-Elongation
factor-G and GTP
What three AAs must patients with maple syrup urine disease not eat? - ANSWER✔✔-
Isoleucine, leucine, and valine
COPYRIGHT © 2025 BY OLIVIA GREENWAYS, ALL RIGHTS RESERVED 2
,How many high-energy bonds are used to activate an AA? - ANSWER✔✔-2 ATPs, via
the amino acyl tRNA synthase enzyme
What water-soluble vitamin deficiency results in Pellagra? - ANSWER✔✔-Niacin (B3)
What glycolytic enzyme has a high Vmax, high Km, and low affinity for glucose? -
ANSWER✔✔-Glucokinase
How many ATPs are generated per acetyl coenzyme A (CoA)? - ANSWER✔✔-12 ATPs
per acetyl CoA that enter the tricarboxylic acid (TCA) cycle (Krebs cycle)
What cytoplasmic pathway produces NADPH and is a source of ribose 5-phosphate? -
ANSWER✔✔-HMP shunt
What is the main inhibitor of pyruvate dehydrogenase? - ANSWER✔✔-Acetyl CoA
(pyruvate to acetyl CoA)
Where on the Codon and Anticodon does the wobble hypothesis take place? -
ANSWER✔✔-3' end of the codon (third position) on mRNA and 5' end of the anticodon
(first position) on tRNA.
What DNA excision and repair enzyme is deficient in patients with xeroderma
pigmentosum? - ANSWER✔✔-Excision endonuclease, which removes thiamine dimers
from DNA
What form of bilirubin is carried on albumin? - ANSWER✔✔-Unconjugated (indirect)
COPYRIGHT © 2025 BY OLIVIA GREENWAYS, ALL RIGHTS RESERVED 3
, What are the two Ketogenic AAs? - ANSWER✔✔-Leucine and lysine
Which organisms have polycistronic mRNA? - ANSWER✔✔-Prokaryotes. Polycistronic
and prokaryotes both start with P.
As what compound do the carbons for fatty acid synthesis leave the mitochondria? -
ANSWER✔✔-Citrate, via the citrate shuttle
What four substances increase the rate of gluconeogenesis? - ANSWER✔✔-1. Glucogon
2. NADH
3. Acetyl CoA
4. ATP
With what three enzymes is TPP associated? - ANSWER✔✔-1. alpha-Ketoglutarate
dehydrogenase
2. Pyruvate dehydrogenase
3. Transketolase
What test uses very small amounts of DNA that can be amplified and analysed without
the use of Southern blotting or cloning? - ANSWER✔✔-PCR
What approtein is required for the release of chylomicrons from the epithelial cells into
the lymphatics? - ANSWER✔✔-apo B-48
COPYRIGHT © 2025 BY OLIVIA GREENWAYS, ALL RIGHTS RESERVED 4
Questions With 100% Solved Correct
Answers Latest Update
What are the three posttranscriptional modifications? - ANSWER✔✔-1. 7-methyl
guanine cap on the 5' end
2. Addition of the poly(A) tail to the 3' end
3. Removal of introns
What AA is the major carrier of nitrogen byproducts from most tissues in the body? -
ANSWER✔✔-Glutamine
What two AAs have a pKa of 4? - ANSWER✔✔-Aspartic acid and glutamic acid
How many acetyl CoAs per glucose enter into the TCA cycle? - ANSWER✔✔-2 acetyl
CoA per glucose, producing 12 ATPs per acetyl CoA, resulting in a total 24 ATPs
produced from glucose (via acetyl CoA) enter the TCA cycle
COPYRIGHT © 2025 BY OLIVIA GREENWAYS, ALL RIGHTS RESERVED 1
,What topoisomerase makes ssDNA cuts, requires no ATP, relaxes supercoils (only
negative in prokaryotes, both for eukaryotes), and acts as the swivel in front of the
replication fork? - ANSWER✔✔-*Topoisomerase I (Relaxase)*
- what drugs inhibit this?
Autoantibodies targeted against type I topoisomerase are called anti-Scl-70 antibodies,
named by the association with scleroderma
-Drugs which poison Eukaryotic Topo I e.g. camptothecin, Topotecan
In Prokaryotes, what is the name of the RNA sequence that ribosomes bind to so
translation can occur? - ANSWER✔✔-Shine-Dalgarno sequence
Name the pattern of genetic transmission: both M and F are affected; M-to-M
transmission may be present; both parents must be carriers; the trait skips generations;
two mutant alleles are needed for disease; and affected children may be born of
unaffected adults? - ANSWER✔✔-Autosomal recessive
What factors are needed for translation in prokaryotes? - ANSWER✔✔-Elongation
factor-G and GTP
What three AAs must patients with maple syrup urine disease not eat? - ANSWER✔✔-
Isoleucine, leucine, and valine
COPYRIGHT © 2025 BY OLIVIA GREENWAYS, ALL RIGHTS RESERVED 2
,How many high-energy bonds are used to activate an AA? - ANSWER✔✔-2 ATPs, via
the amino acyl tRNA synthase enzyme
What water-soluble vitamin deficiency results in Pellagra? - ANSWER✔✔-Niacin (B3)
What glycolytic enzyme has a high Vmax, high Km, and low affinity for glucose? -
ANSWER✔✔-Glucokinase
How many ATPs are generated per acetyl coenzyme A (CoA)? - ANSWER✔✔-12 ATPs
per acetyl CoA that enter the tricarboxylic acid (TCA) cycle (Krebs cycle)
What cytoplasmic pathway produces NADPH and is a source of ribose 5-phosphate? -
ANSWER✔✔-HMP shunt
What is the main inhibitor of pyruvate dehydrogenase? - ANSWER✔✔-Acetyl CoA
(pyruvate to acetyl CoA)
Where on the Codon and Anticodon does the wobble hypothesis take place? -
ANSWER✔✔-3' end of the codon (third position) on mRNA and 5' end of the anticodon
(first position) on tRNA.
What DNA excision and repair enzyme is deficient in patients with xeroderma
pigmentosum? - ANSWER✔✔-Excision endonuclease, which removes thiamine dimers
from DNA
What form of bilirubin is carried on albumin? - ANSWER✔✔-Unconjugated (indirect)
COPYRIGHT © 2025 BY OLIVIA GREENWAYS, ALL RIGHTS RESERVED 3
, What are the two Ketogenic AAs? - ANSWER✔✔-Leucine and lysine
Which organisms have polycistronic mRNA? - ANSWER✔✔-Prokaryotes. Polycistronic
and prokaryotes both start with P.
As what compound do the carbons for fatty acid synthesis leave the mitochondria? -
ANSWER✔✔-Citrate, via the citrate shuttle
What four substances increase the rate of gluconeogenesis? - ANSWER✔✔-1. Glucogon
2. NADH
3. Acetyl CoA
4. ATP
With what three enzymes is TPP associated? - ANSWER✔✔-1. alpha-Ketoglutarate
dehydrogenase
2. Pyruvate dehydrogenase
3. Transketolase
What test uses very small amounts of DNA that can be amplified and analysed without
the use of Southern blotting or cloning? - ANSWER✔✔-PCR
What approtein is required for the release of chylomicrons from the epithelial cells into
the lymphatics? - ANSWER✔✔-apo B-48
COPYRIGHT © 2025 BY OLIVIA GREENWAYS, ALL RIGHTS RESERVED 4
