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SBI 4U Name: ______________________________
1 | P a g e Molecular Genetics Cory Cultrera and Kendra Vice
Molecular Genetics Test
Overall Expectation:
‐ Demonstrate an understanding of concepts related to molecular genetics, and how genetic
modification is applied in industry and agriculture
Specific Expectation(s):
‐ Explain the steps involved in the process of protein synthesis and how genetic expression is
controlled in prokaryotes and eukaryotes by regulatory proteins
Knowledge and Understanding (27)
Multiple Choice (10 marks)
Circle the answer that is the most correct (1 mark each):
1. During transcription, ______________ binds to the promoter region and begins attaching
nucleotides on a complimentary mRNA strand.
a. DNA Helicase
b. RNA Polymerase
c. Ribosomes
d. tRNA
2. Each three‐letter unit of a mRNA molecule is called a :
a. Intron
b. Transposon
c. Codon
d. Interferon
3. A thymine on a DNA strand will pair with a ___________ on a complimentary mRNA strand
a. Uracil
b. Guanine
c. Adenine
d. Thymine
4. In the final stages of transcription, a poly‐A tail is added to:
a. The 5’ end of the DNA strand
b. The 3’ end of the DNA strand
c. The 5’ end of the mRNA strand
d. The 3’ end of mRNA strand
5. Which of the following is not a step in the synthesis of the polypeptide chain:
a. Initiation
b. Elongation
c. Preparation
d. Termination
SBI 4U Name: ______________________________
2 | P a g e Molecular Genetics Cory Cultrera and Kendra Vice
6. A mutation which results in the changing of all the codons following the error is called a
_______________ mutation:
a. Frameshift
b. Point
c. Chromosomal
d. Germ
7. The lac operon…
a. is a group of genes used to control the transcription of the lactose metabolizing protein
in eukaryotic cells
b. is a protein that metabolizes lactose in prokaryotic cells
c. is a group of genes used to control the transcription of the lactose metabolizing protein
in prokaryotic cells
d. is a protein that metabolizes lactose in eukaryotic cells
8. In the lac operon lactose acts as a…
a. Promoter
b. Inducer
c. Enzyme
d. Coding region
9. Alternative splicing is an example of which type of control…
a. Transcriptional
b. Posttranslational
c. Translational
d. Posttranscriptional
10. During translation what is the purpose of the poly A tail?
a. Activates binding molecules in the nuclear membrane to speed up movement
b. Acts to stabilize the mRNA and allows the strand to survive longer in the cytoplasm
c. Acts as a promoter region whictrh attaches the large and small ribosomal subunits
d. Activates the binding of ubiquitin to tag the mRNA for degradation
True/ False (9 marks)
Answer the following questions either true (T) or false (F):
1. Before the mRNA can leave the nucleus, non‐coding regions called exons must be removed by
spliceosomes.
2. Translation occurs in the nucleus of the cell.
3. To start the process of translation, the start codon “AUG” must be recognized by the ribosome.
4. A non‐sense mutation is where the substitution of a nucleotide at the DNA level, results in the
early production of a STOP codon during translation.
SBI 4U Name: ______________________________
3 | P a g e Molecular Genetics Cory Cultrera and Kendra Vice
5. Gene mutations always have a harmful effect.
6. If lactose is present in the prokaryotic cell there is a site on the lac repressor where lactose
binds, this renders the protein active and prevents transcription
7. Transcriptional control is the most common type of regulation
8. Methylation inhibits transcription, it is also called quieting transcription
9. In prokaryote cells, once lactose is metabolized and the concentration in the cell decreases, the
repressor is activated and transcription is stopped
Matching (8 marks)
Match the term to the correct definition:
1. Producing RNA from a sections of DNA
2. Binds to the promoter region of DNA and attaches nucleotides on a complementary mRNA strand
3. Genes which are constantly transcribed
4. Producing a polypeptide from mRNA
5. Always present in the cell, in the absence of lactose, binds to the operator and prevents RNA polymerase from binding
6. –CH3 added to cytosine bases in promoter inhibits transcription, also called silencing
7. Provides stability to the mRNA strand during translation
8. Proteins tagged, recognized for degradation
A. lac repressor
B. Ubiquitin
C. Translation
D. Methylation
E. poly(A) tail
F. Constitutive genes
G. Transcription
H. RNA Polymerase
Thinking and Inquiry (13)
Fill in the Blank (13 marks; one mark for each blank)
1. The central dogma, a term coined by Watson and Crick, describes the flow of information from
____________ to ___________ to _________________ within a living system.
2. During transcription when the mRNA strand is being edited, the 5’ end is capped with a
____________________. In addition, a long strand of adenine molecules called a
___________________ is added to the 3’ end of the mRNA.
SBI 4U Name: ______________________________
4 | P a g e Molecular Genetics Cory Cultrera and Kendra Vice
3. It would be inefficient to transcribe and translate all its genes at all times, unregulated genes are
also called __________________________________________, an example of this type of gene
are housekeeping genes which transcribe for proteins which are used constantly in the cell.
4. There are different methods for controlling gene expression in prokaryotes, either the genes
could be regulates using ____________________________________ which prevent
transcription from occurring or _____________________________________ which increase the
rate of transcription
5. There are three methods of post‐ translational regulation, these include;
_____________________________________, _____________________________________ and
_____________________________________.
6. The use of a masking protein is an example of post‐ transcriptional regulation, when bound the
mRNA __________________________________________________________________.
7. An insertion or deletion of a nucleotide from the DNA strand during protein synthesis is a type
of _____________________ mutation.
Application (13)
1. Using the genetic code table in the appendix, and your knowledge of transcription and
translation, take the following DNA sequence and produce the corresponding polypeptide
sequence. Be sure to include all strands that are formed and label each end of the strands:
DNA Sequence: 5’ TAC CCC ATT TAA CAT TAC ACT 3’ (6 marks)
SBI 4U Name: ______________________________
5 | P a g e Molecular Genetics Cory Cultrera and Kendra Vice
2. Alternative splicing is an example of post‐ transcriptional regulation. How is alternative splicing
useful to eukaryotic gene expression? Feel free to use diagrams to explain your answer.
(3 marks)
3. All human beings have a rich growth of E. coli bacteria in their large intestine. Will the lac
operon in the bacteria present in a lactose‐intolerant individual who is careful never to consume
anything with lactose (milk sugar) be activated or repressed? Explain. (4 marks)
SBI 4U Name: ______________________________
6 | P a g e Molecular Genetics Cory Cultrera and Kendra Vice
Communication (10)
1. Using the following diagram, organize and explain the process of controlling gene expression
shown, you may reference the diagram in your answer. (10 marks)
SBI 4U Name: ______________________________
7 | P a g e Molecular Genetics Cory Cultrera and Kendra Vice
APPENDIX