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Biology 12
DNA/Protein Synthesis Chapter Review
DNA Structure and Replication
1. a) DNA, b) protein coats,
c)DNA (i.e. P—32), d) genetic
2. a) 3-D structure, b) pyrimidines, c) Thymine d) Cytosine
3. a) sugar, b) Guanine, c) Cytosine d) phosphate, e) helix f) hydrogen
g) T
h) complementary
4. a)
b) antiparallel, c) helicase d) DNA polymerase d) semiconservative e) replicate
5. a) nucleus b) proteins c) ribose d) Uracil e) cytoplasm f) ribosomal
RNA g) transfer RNA
h) polypeptide i) gene
6. a) Transcription b) mRNA c) translation d) amino acids e) triplet f)
codon g) AUG (Start)
7. a) RNA b) polymerase c) U, A, C, G d) introns e) exons f) ribozymes
g) mRNA
8. a) transfer b) anticodon c) DNA d) tRNA synthetase e) ribosomal
(rRNA) f) nucleolus
9. a) initiation b) ribosomal c) elongation d) amino acids e) termination
f) polysome
Part A: True or False Questions
1. DNA replication is semi-conservative because each new double helix has
one old strand and one new strand
Answer: True
2. A gene is a segment of DNA that specifies the sequence of amino acids in an
enzyme
Answer: False
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Biology 12
DNA/Protein Synthesis Chapter Review
3. The sequence of tRNA codons dictates the order in which amino acids
become incorporated into a polypeptide
Answer: False
4. Segments of DNA not part of a gene are called exons, whereas those
segments expressed are called introns.
Answer: False
Part B: Short Answers
5. If the bases in one strand of DNA are CATTAG, what would be the
complementary bases on the opposite strand?
A: --GTAATC—
6. If the bases in one strand of DNA are CATTAG, what would be the mRNA
bases used for transcription?
A: --GUAAUC—
7. How many nucleotide bases are necessary in a codon to code for the
twenty different amino acids found in a protein assuming we only have A,
G, C, & T?
A: Recall……
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Biology 12
DNA/Protein Synthesis Chapter Review
Therefore, if we maintain the four different bases that exist now (i.e.
A,C,G,T), we would need only four bases and a triplet codon
8. If there were a total of 80 amino acids in living organisms, how many
nucleotide bases would be necessary to code for all of them in a codon?
A: recall
Then, 43 would only give us 64 and not 80 different possibilities of amino
acids. Thus, we would need a codon of four bases as 44 = 236
9. What is the difference between a purine and a pyrimidine?
A. Purines are made of 2 ring structures whereas pyrimidines are only
made of one nitrogenous ring
10.What is the function of the following:
a) tRNA- moves a particular amino acid to the ribosome mRNA complex
b) mRNA—caries the information to make a particular polypeptide
c) ribosome—the organelle where proteins are made
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Biology 12
DNA/Protein Synthesis Chapter Review
11.What is the role of ribozyme
A: Ribozymes are RNA enzymes that remove introns from mRNA
12.Describe the structure of DNA
 DNA is made of a double strand of nucleotides
 Each nucleotide contains a deoxyribose sugar, a nitrogenous base
and a phosphate group
 The nucleotides are joined together along their sugar and phosphate
groups with the bases sticking out from each strand
 The double strand of DNA runs is an antiparallel structure which
means that each of the two strands runs in opposite direction to that
of its complementary strand
 The bases in DNA are bonded together using hydrogen bonds
according to the following base pairing rules A-T, G-C
13.How many tRNA molecules attach to one ribosome/mRNA complex at the
same time
 There are a total of 3 (E,P,A sites) that can bind at any one time
14. in order:
Amino acid
anticodon
mRNA
Glycine
CCA
GGU
Valine
CAU
GUA
Isoleucine
UAA
AUU
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Biology 12
DNA/Protein Synthesis Chapter Review
15. Why is DNA replication said to be semi-conservative?
 Because one strand of the new double stranded DNA is from the
original strand and the other is new
16. What is meant by the one-gene-one-enzyme hypothesis?
 That one gene is responsible for producing one unique enzyme
 We now know that this is not completely true and this has been
replaced by the one gene one polypeptide theory
17. Is the genetic code essentially universal?
 Yes, meaning that the same codon codes for the same amino acid in
bacteria as it does in fungi and all other organisms including humans
18. What are the two types of molecules in the two sub-units of a ribosome?
Where is the rRNA produced?
 rRNA and proteins
 nucleolus
19.Describe the 3-D structure of DNA
 See question 8 above
20. List Chargaff’s rule that apply to DNA
 The number of purines = the number of pyrimidines in DNA
 Also, the of #A = #T and #G = #C
21.Name the two biological molecules found in chromosomes
 DNA and histone proteins
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Biology 12
DNA/Protein Synthesis Chapter Review
22. List the three basic functions of DNA as a hereditary material, must be able
to do.
 Carry the information to produce proteins
 Copy itself
 Allow for mutations
23.Name the two scientists who are given the credit for discovering the
structure of DNA
 Watson and Crick
24.What was the conclusion of the experiment in which radioactive proteins
and DNA were labelled in viruses?
 That DNA was the genetic material that was being transferred from
viruses to bacterial cells
25.Name the specific type of RNA that is used to produce the correct order of
amino acids in a polypeptide
 mRNA
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