DNA, RNA, and Protein Synthesis
Study Guide Answers
1. Results from Griffith’s experiment.
• Griffith worked with 2 strains of bacteria: R strain
(harmless) and S strain (which caused pneumonia).
• Mice injected with R strain were fine.
• Mice injected with S strain developed pneumonia within
days and died.
• He killed the S strain bacteria with heat, injected it into
mice and they lived.
• Then he mixed the heat-killed S strain bacteria with R strain
bacteria and injected them. They died!
• Conclusion: the genetic material in the S bacteria was
passed on, making the R bacteria deadly as well 
Transformation!
2. Results of Avery’s experiment. Idea
he is credited with discovering?
• Avery wanted to know
if the “transforming
agent” that Griffith
saw in his experiment
was DNA, RNA, or
protein.
• His experiment
concluded that the
genetic material
(“transforming agent”)
was DNA.
3. Hershey and Chase experiment and
results?
• They studied the virus that infects bacteria
cells and makes them produce more viruses.
• Looking to see what type of genetic material is
passed from the virus to the bacteria.
• They concluded that DNA is the molecule that
holds the genetic information and is passed
along.
4. Watson and Crick are credited with
discovering the shape of DNA!!!!
5. DNA is
located in the
nucleus!!!
6. Structure of the DNA molecule.
• Double helix shape (like a spiral staircase)
• Made up of nucleotides (next slide)
• Backbone is made up of alternating sugar and
phosphates
• Middle of molecule is made up of A, T, C, G
and held together by hydrogen bonds
• DNA is a very large molecule!
• Sugar in DNA is deoxyribose!
7. A nucleotide…
8. Deoxyribose is the sugar in DNA!
9. Chargaff made the
observation that every
DNA molecule always
had the same amount
of adenine as it had of
thymine and the same
amount of guanine as
it had of cytosine.
10. What is DNA replication? Where
does it take place?
• It is the process by which new DNA molecules
are made.
• It occurs in the nucleus.
11. What is the semi-conservative
model of DNA replication?
• It says that new DNA strands
are synthesized using the old
strands as a template.
• So, each new molecule of
DNA that is produced has
one of the parent strands
and one new one.
12. The enzymes which unwinds the
double helix and breaks the hydrogen
bonds?
Helicase
13. The enzyme that adds nucleotides
in order to create DNA?
DNA polymerase
14. The enzyme that synthesizes RNA
primer?
primase
15. Difference between leading and
lagging strands?
• Leading: synthesized continuously, toward the
opening of the rep. fork
• Lagging: synthesized discontinuously, in the
opposite direction (away from the fork.)
16. The enzyme that links Okazaki
fragments?
Ligase
17. Make the complementary strand
of DNA.
GTTCAACCGAT
CAAGTTGGCTA
18. Explain what occurs in DNA
replication.
• DNA molecule is split by helicase, forming a
replication fork.
• RNA primer is synthesized.
• DNA polymerase attaches and begins adding
nucleotides to exposed bases.
• End product: 2 DNA molecules, each with 1
parental strand and 1 new strand
19. 3 similarities and 3 differences
between DNA and RNA?
• Similarities: both are nucleic acids, both are
made up of nucleotides, both created in
nucleus, both contain sugar, phosphate,
adenine, cytosine, guanine, etc.
• Differences: sugar, DNA is double stranded
and RNA is single stranded, DNA has thymine
and RNA has uracil, DNA must stay in nucleus
and RNA can leave, etc.
20. Explain what occurs in
transcription.
• DNA molecule is split by
helicase.
• RNA polymerase moves along
ONE strand of DNA and adds
nucleotides to exposed bases.
• When the stop sequence is
reached, mRNA detaches and
is free to go.
• Start: DNA, End: mRNA
21. 3 Types of RNA and their
functions.
• mRNA: carries
instructions from
nucleus to
cytoplasm/ribosomes
• tRNA: carries and
attaches amino acids to
make a protein
• rRNA: makes up the
ribosomes
22. A codon is a 3 letter segment
of mRNA that codes for a specific
amino acid.
23. Type of RNA that carries amino
acids?
tRNA
24. Explain what occurs during
translation.
• Small subunit of ribosome binds to mRNA upstream of the
start sequence.
• Moves downstream until it reaches the start sequence, then
large subunit attaches.
• tRNA anticodons match up with mRNA codons and attach
their amino acids to create a polypeptide chain.
• Stop sequence is reached, mRNA and protein are released.
25. Genes contain instructions for
assembling proteins!
26. Role of RNA polymerase?
• Creates mRNA molecule by adding nucleotides
to exposed bases on a strand of DNA.
27. During transcription, mRNA is
produced!
28. The enzyme at work during
transcription? How does it work?
• RNA polymerase
• It moves along ONE strand of DNA, adding
nucleotides to the exposed bases to create a
strand of mRNA.
29. The codons below code for:
AUG-GCC-AUC-GGU-CUA-GUUUAG
(start)Methionine-alaninephenylalanine-glycine-leucinevaline-stop
30. Complementary DNA sequence?
mRNA: AUG GCC AUC GGU CUA GUU UAG
DNA: TAC CGG TAG CCA GAT CAA ATC
31. The function of tRNA is to
carry amino acids.