Name: SBI 4U. Gene Expression Quiz. Overall Expectation:

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1 Gene Expression Quiz 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 Multiple Choice Circle the answer that is the most correct: 1. 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 2. 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 3. In the lac operon lactose acts as a a. Promoter b. Inducer c. Enzyme d. Coding region 4. Alternative splicing is an example of which type of control a. Transcriptional b. Posttranslational c. Translational d. Posttranscriptional 1 P a g e

2 5. 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 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. 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 3. Transcriptional control is the most common type of regulation 4. Methylation inhibits transcription, it is also called quieting transcription 5. In prokaryote cells, once lactose is metabolized and the concentration in the cell decreases, the repressor is activated and transcription is stopped Matching 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. CH 3 added to cytosine bases in promoter inhibits transcription, also called silencing 7. Provides stability to the mrna strand during translation A. lac repressor B. Ubiquitin C. Translation D. Methylation E. poly(a) tail F. Constitutive genes G. Transcription H. RNA Polymerase 8. Proteins tagged, recognized for degradation 2 P a g e

3 Thinking and Inquiry Fill in the Blank 1. 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. 2. 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 3. There are three methods of post- translational regulation, these include;, and. 4. The use of a masking protein is an example of post- transcriptional regulation, when bound the mrna. Application Short Answer 1. 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 P a g e

4 2. 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. Communication Short Answer 1. Using the following diagram, organize and explain the process of controlling gene expression shown, you may reference the diagram in your answer. 4 P a g e

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