Bio 156 Exam 3 Questions &
Answers (Updated 2026)
What is the BASE PAIRING RULE for DNA? -Correct Answer ✔-A=T
C=G
What is the base pairing rule for RNA? -Correct Answer ✔-A=U
C=G
During the s-phase of interphase, the cell replicates its DNA using "SEMI-
CONSERVATIVE REPLICATION". Explain WHAT this means and WHY it is so
important -Correct Answer ✔-WHAT: Way to copy DNA using master strand as
instructions on how to build the other side
-half of something is going to be conserved, half preserved
WHY: It's a very careful way to copy DNA
Explain exactly what happens during "semi-conservative DNA replication" -Correct
Answer ✔-The cell will use SEMI - CONSERVATIVE DNA REPLICATION to copy all
of its DNA prior to mitosis or meiosis. In this process, the original (master?) strand of
DNA will be split in half by DNA HELICASE and then DNA POLYMERASE will copy
each half to produce two new and identical DNA molecules from the original.
List 3 differences between DNA and RNA -Correct Answer ✔-DNA:
-double stranded
-nitrogenous bases: ATCG
-base pairing rule: A=T & C=G
-location: nucleus
RNA:
-single stranded
-nitrogenous bases: AUCG
-base pairing rule: A=U & C=G
-location: nucleus & cytoplasm
What is a chromosome? Draw a "duplicated CHROMOSOME" and LABEL all the parts
WHEN do chromosomes first appear in the cell cycle? -Correct Answer ✔-
Chromosome: Condensed/compressed superspooled DNA molecule
, WHEN: during PROPHASE
(label parts: centromere & sister chromatids)
Describe 2 cellular events that happen during INTERPHASE
Describe 2 cellular events that happen during INTERPHASE -Correct Answer ✔--Cell
growth
-DNA replication
-Protein synthesis
(more specifically)...
-G1 phase = cell growth, organelles double
-S phase = synthesis of DNA, semi-conservative DNA replication
-G2 phase = protein synthesis, preparation for mitosis +++
-G0 phase = specialized cell "jobs" = secretion, muscle contraction,
Use the mRNA strand and the CODON KEY (On back) to answer the following
questions;
a. describe the nucleotide sequence of the original DNA strand used to make the mRNA
&
b. describe the primary structure of the protein in the gene on this DNA. -Correct
Answer ✔-DNA TAC AAA TCT CCA TTT GGG ACG ATT
mRNA AUG UUU AGA GGU AAA CCC UGC UAA
Protein Start●Phe● Arg●Gly● Lys●Pro●Cys● Stop
BRIEFLY describe the function/role of all these molecules in the protein synthesis
"story".
adenine, thymine, cytosine, guanine ♦DNA polymerase ♦DNA unzipase/Helicase RNA
polymerase ♦Messenger RNA (mRNA) ♦Ribosomal RNA (rRNA) ♦Transfer RNA (tRNA)
♦glycine or any another amino acid ♦protein polymerase -Correct Answer ✔--Adenine,
thymine, cytosine, guanine: monomer nucleotides used to form the DNA polymer.
-DNA polymerase: the enzyme that copies and repairs DNA.
-DNA unzipase/Helicase: the enzyme that separates the two sides of the DNA molecule
by disrupting
the hydrogen bonds between complimentary nucleotides.
-RNA polymerase: the enzyme that copies and repairs RNA
Answers (Updated 2026)
What is the BASE PAIRING RULE for DNA? -Correct Answer ✔-A=T
C=G
What is the base pairing rule for RNA? -Correct Answer ✔-A=U
C=G
During the s-phase of interphase, the cell replicates its DNA using "SEMI-
CONSERVATIVE REPLICATION". Explain WHAT this means and WHY it is so
important -Correct Answer ✔-WHAT: Way to copy DNA using master strand as
instructions on how to build the other side
-half of something is going to be conserved, half preserved
WHY: It's a very careful way to copy DNA
Explain exactly what happens during "semi-conservative DNA replication" -Correct
Answer ✔-The cell will use SEMI - CONSERVATIVE DNA REPLICATION to copy all
of its DNA prior to mitosis or meiosis. In this process, the original (master?) strand of
DNA will be split in half by DNA HELICASE and then DNA POLYMERASE will copy
each half to produce two new and identical DNA molecules from the original.
List 3 differences between DNA and RNA -Correct Answer ✔-DNA:
-double stranded
-nitrogenous bases: ATCG
-base pairing rule: A=T & C=G
-location: nucleus
RNA:
-single stranded
-nitrogenous bases: AUCG
-base pairing rule: A=U & C=G
-location: nucleus & cytoplasm
What is a chromosome? Draw a "duplicated CHROMOSOME" and LABEL all the parts
WHEN do chromosomes first appear in the cell cycle? -Correct Answer ✔-
Chromosome: Condensed/compressed superspooled DNA molecule
, WHEN: during PROPHASE
(label parts: centromere & sister chromatids)
Describe 2 cellular events that happen during INTERPHASE
Describe 2 cellular events that happen during INTERPHASE -Correct Answer ✔--Cell
growth
-DNA replication
-Protein synthesis
(more specifically)...
-G1 phase = cell growth, organelles double
-S phase = synthesis of DNA, semi-conservative DNA replication
-G2 phase = protein synthesis, preparation for mitosis +++
-G0 phase = specialized cell "jobs" = secretion, muscle contraction,
Use the mRNA strand and the CODON KEY (On back) to answer the following
questions;
a. describe the nucleotide sequence of the original DNA strand used to make the mRNA
&
b. describe the primary structure of the protein in the gene on this DNA. -Correct
Answer ✔-DNA TAC AAA TCT CCA TTT GGG ACG ATT
mRNA AUG UUU AGA GGU AAA CCC UGC UAA
Protein Start●Phe● Arg●Gly● Lys●Pro●Cys● Stop
BRIEFLY describe the function/role of all these molecules in the protein synthesis
"story".
adenine, thymine, cytosine, guanine ♦DNA polymerase ♦DNA unzipase/Helicase RNA
polymerase ♦Messenger RNA (mRNA) ♦Ribosomal RNA (rRNA) ♦Transfer RNA (tRNA)
♦glycine or any another amino acid ♦protein polymerase -Correct Answer ✔--Adenine,
thymine, cytosine, guanine: monomer nucleotides used to form the DNA polymer.
-DNA polymerase: the enzyme that copies and repairs DNA.
-DNA unzipase/Helicase: the enzyme that separates the two sides of the DNA molecule
by disrupting
the hydrogen bonds between complimentary nucleotides.
-RNA polymerase: the enzyme that copies and repairs RNA
