BIOCHEM ACS ACTUAL FINAL EXAM 2026
COMPREHENSIVE TEST PAPER WITH
DETAILED ANSWERS
⩥ adenine and guanine. Answer: what are the two nitrogenous bases that
are purines
⩥ purines. Answer: Bases with a double-ring structure.
(pyrimidine and imidazole ring)
⩥ pyrimidine. Answer: single-ring nitrogenous base
⩥ cytosine, thymine, uracil. Answer: what nitrogenous bases are
pyrimidines
⩥ -A-T has 2 H bonds
-G-C has 3 H bonds. Answer: how many H bonds are their between A-
T/U? what about G-C?
⩥ GC rich DNA because it had 3 H bonds. Answer: which has a higher
melting point GC rich DNA or AT rich DNA and why?
,⩥ B DNA. Answer: type of DNA; 0.34 nm between bp, 3.4 nm per turn,
about 10 bp per turn; right handed helix, the bases are stacked parallel
and bases are facing each other at the same level making it have aa high
H-bonding
⩥ A DNA. Answer: type of DNA; Cylindrical CORE. 11bp per turn.
forms when DNA is dehydrated, more tightly wound than B DNA(right
handed helix). The bases are not parallel but at an angle (this angle gives
it a less strong H-bonding making A conformation less stable than B
DNA)
⩥ Z DNA. Answer: type of DNA; 2 bp per turn. No grooves, left handed
helix, occurs in G/C rich regions
⩥ restriction endonucleases (REN). Answer: enzymes that recognize
specific sequences of nucleotides and cleave strands of DNA into
fragments wherever those sequences occur
⩥ dideoxy sequencing. Answer: a method of DNA sequencing that uses
dideoxyribonucleotides to terminate the growth of DNA strands; , DNA
polymerase will stop when ddNTPs are incorporated onto the DNA
strand. ddNTPs are color labeled for different bases. (ex: ddGTP is
yellow). Determines the nucleotide sequence (A,T,G,C) in one strand
⩥ PCR. Answer: -separates strands by denaturing at 95 C
-anneal primers 65 deg C
, -extend primers w/ Taq polymerase
-generates millions of copies of DNA
⩥ helicase. Answer: protein that catalyzes the ATP-dependent unwinding
of DNA double helices
⩥ single stranded binding protein. Answer: proteins that bind to the
unwound strands to prevent reannealing
⩥ DNA polymerase. Answer: enzyme responsible for DNA replication,
uses ssDNA as the template and makes complementary strand by
polymerizing deoxynucleotides, synthesis in 5' to 3'
⩥ RNAse H. Answer: a nuclease that specifically degrades RNA chains
in DNA in eukaryotes
⩥ DNA ligase. Answer: seals nicks in double stranded DNA where a 3'-
OH and 5'-phosphate are juxtaposed
⩥ telomerase. Answer: adds telomeres to the ends of chromosomal
DNA, an RNA-dependent DNA polymerase (has its own RNA primer,
does need external RNA primers)
COMPREHENSIVE TEST PAPER WITH
DETAILED ANSWERS
⩥ adenine and guanine. Answer: what are the two nitrogenous bases that
are purines
⩥ purines. Answer: Bases with a double-ring structure.
(pyrimidine and imidazole ring)
⩥ pyrimidine. Answer: single-ring nitrogenous base
⩥ cytosine, thymine, uracil. Answer: what nitrogenous bases are
pyrimidines
⩥ -A-T has 2 H bonds
-G-C has 3 H bonds. Answer: how many H bonds are their between A-
T/U? what about G-C?
⩥ GC rich DNA because it had 3 H bonds. Answer: which has a higher
melting point GC rich DNA or AT rich DNA and why?
,⩥ B DNA. Answer: type of DNA; 0.34 nm between bp, 3.4 nm per turn,
about 10 bp per turn; right handed helix, the bases are stacked parallel
and bases are facing each other at the same level making it have aa high
H-bonding
⩥ A DNA. Answer: type of DNA; Cylindrical CORE. 11bp per turn.
forms when DNA is dehydrated, more tightly wound than B DNA(right
handed helix). The bases are not parallel but at an angle (this angle gives
it a less strong H-bonding making A conformation less stable than B
DNA)
⩥ Z DNA. Answer: type of DNA; 2 bp per turn. No grooves, left handed
helix, occurs in G/C rich regions
⩥ restriction endonucleases (REN). Answer: enzymes that recognize
specific sequences of nucleotides and cleave strands of DNA into
fragments wherever those sequences occur
⩥ dideoxy sequencing. Answer: a method of DNA sequencing that uses
dideoxyribonucleotides to terminate the growth of DNA strands; , DNA
polymerase will stop when ddNTPs are incorporated onto the DNA
strand. ddNTPs are color labeled for different bases. (ex: ddGTP is
yellow). Determines the nucleotide sequence (A,T,G,C) in one strand
⩥ PCR. Answer: -separates strands by denaturing at 95 C
-anneal primers 65 deg C
, -extend primers w/ Taq polymerase
-generates millions of copies of DNA
⩥ helicase. Answer: protein that catalyzes the ATP-dependent unwinding
of DNA double helices
⩥ single stranded binding protein. Answer: proteins that bind to the
unwound strands to prevent reannealing
⩥ DNA polymerase. Answer: enzyme responsible for DNA replication,
uses ssDNA as the template and makes complementary strand by
polymerizing deoxynucleotides, synthesis in 5' to 3'
⩥ RNAse H. Answer: a nuclease that specifically degrades RNA chains
in DNA in eukaryotes
⩥ DNA ligase. Answer: seals nicks in double stranded DNA where a 3'-
OH and 5'-phosphate are juxtaposed
⩥ telomerase. Answer: adds telomeres to the ends of chromosomal
DNA, an RNA-dependent DNA polymerase (has its own RNA primer,
does need external RNA primers)
