Biol 131
Question Bank
Gene Structure & Function
1. The many different functions and behaviors of living organisms are based on the characteristics of their
cells. Within an organism, each cell’s characteristics in turn are dependent upon the:
A. the types of proteins that are expressed.
B. the particular set of genes that it possesses.
C. the structure of its membranes.
D. the structure of its DNA molecule.
2. The “central dogma” of gene expression consists of which of the following two steps?
A. Gene information is transferred from DNA to an RNA molecule.
B. RNAs are processed to remove introns and splice together exons.
C. RNA carries the information that directs protein synthesis.
D. proteins assume a specific three dimensional shape to become functional
3. Transcription and DNA replication are similar in all the following ways, EXCEPT;
A. The new strand is polymerized in the 5-to-3 direction.
B. During synthesis, nucleotide triphosphates are hydrolyzed to release PPi (pyrophosophate).
C. Complementary base pairing occurs during both processes.
D. Synthesis involves production of small strands that must then be ligated together.
4. Answer the following questions about codons, amino acids and tRNAs.
A. For a three base codon there are ____ possible different codons, and these codons carry the information
necessary to specify ____ different amino acids.
B. A given amino acid may be specified by a number of different codons, ranging from ___ to ___ codons.
One codon, which also specifies the amino acid methionine, also functions as the _________ codon.
Some codons do not specify an amino acid, but rather are called _______ codons.
C. Cells must possess tRNAs with different anticodons to carry the different amino acids. Do you think
that the total number of tRNAs is more likely to be based upon the number of amino acids or the number
of codons? Explain.
5. How does:
A. RNA polymerase know where the beginning of a gene is?
B. RNA polymerase know where to stop transcribing a gene?
C. a spliceosome identify the beginning and end of an intron?
D. a ribosome know where to begin translation?
E. the ribosome know where to end translation?
Biol 131
Question Bank
Genes
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6. Why is a primer needed for DNA replication but not RNA transcription? (Your answer should focus on the
properties of DNA polymerase vs. RNA polymerase.)
7. Indicate where the following processes take place by adding numbered
label lines to the diagram of a eukaryotic cell.
1. Transcription
2. Translation of cytosolic protein
3. Translation of a cell membrane protein
4. RNA splicing
5. DNA replication
8. One way to purify nucleic acids with specific sequences is to allow them to hybridize (bind to) other strands
of nucleic acids with complementary sequences. For example, if RNA with the sequence 3’AUGCAUGCAUGC -5’ were attached to a solid matrix and then incubated with a solution containing
different types of RNA, those with the sequence 5’- UACGUACGUACG-3’ would bind. If all of the nonbound RNAs were washed off, only the bound ones would remain.
A. What sequence of bases is shared by all eukaryotic mRNAs? What is the function of this sequence?
B. Suppose you wished to separate the mRNAs from a mixture of all RNAs extracted from a eukaryotic
organism. If you applied the strategy described above, what sequence of nucleotides would you use?
C. Would this strategy work for both eukaryotes and prokaryotes? Why?
9. Answer the following questions about RNAs.
A. Name three modifications that are made to mRNA molecules in eukaryotic cells before the RNA
molecule becomes a mature mRNA.
1.
2.
3.
B. The length of a particular gene in human DNA, measured from the start codon to the end of the proteincoding region, is 10,000 nucleotides, yet the mRNA that is being used to translate the protein for this
gene in the cytosol is 4000 nucleotides. What is the most likely reason for this discrepancy?
C. Why would the presence of introns in RNA molecules in prokaryotes cause problems? Consider where
transcription and translation occur in prokaryotes.
Biol 131
Question Bank
Genes
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10. Which one of the following statements about the genetic code is correct?
A. All codons specify more than one amino acid.
B. Some amino acids are specified by a single codon.
C. All amino acids are specified by more than one codon.
D. The genetic code is different in prokaryotes and eukaryotes.
11. As you know, ribosomes contain both rRNAs and many proteins. Outline the path through the cell that a
ribosomal protein (and its mRNA) must follow from its original transcription in the nucleus to final function
in a whole ribosome. To get you started, this path would begin with “the transcription of the ribosomal gene
into an mRNA in the nucleus. The mRNA would then move into the cytosol and …” (don’t forget the role
of the nucleolus in ribosome subunit assembly).
Use this table of codons to answer the following questions as needed
12A.
The anticodon of the codon 5-GAA-3 is 5’- __ __ __ - 3’ (be mindful of orientation)
12B.
Which amino acid would you expect a tRNA with the anticodon 5-CUU-3 to carry?
A. Lysine (Lys)
D. Leucine (Leu)
B. Glutamic acid (Glu)
E. Phenylalanine (Phe)
C. Glutamine (Gln)
13. In the two diagrams to the right, label the:
A. Ribosomal small subunit
B. Ribosomal large subunit
C. P-tRNA site
D. A-tRNA site
E. E-tRNA site
F. tRNA anticodon
G. AA- binding site on the tRNA
Biol 131
Question Bank
Genes
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14. Using the DNA sequence given below, answer the following questions:
A. If an RNA polymerase were to transcribe the gene from left to right, is the top or the bottom strand
serving as the template? _________________
B. A ‘promoter’ is said to be “up-stream” of the coding region; does that mean toward the 3’ or the 5’ end?
__________________________
C. In the space below write out the sequence of the mRNA that would be transcribed (label the 5 and 3
ends of your RNA molecule). Find and circle the start codon.
D. What is the amino acid sequence of the peptide that would be translated from this mRNA.
E. How do we know that this is not the complete sequence for this protein?
The following is a segment of DNA containing the beginning of a gene.
(The superscripts are used in question 15.)
3- GGCATACGGT1AGTCAA2GAGACAG3TTACC -5
5- CCGTATGCCA1TCAGTT2CTCTGTC3AATGG -3
15. Using the DNA sequence given above indicate whether each of the following sequence changes will result
in a:
A. nonsense mutation
C. reading frame mutation E. silent mutation
B. missense mutation
D. trinucleotide expansion F. single amino acid change
1. _____ multiple replications of the triplet labeled:
2. _____ substitution of a
C
G
CAA2
GTT2
T1
base pair for the A1 pair in the sequence.
Bas
T1
e
3. _____ deletion of the A1 base pair.
4. _____ addition of a new
5. _____ substitution of an
T
A
T
A
pair immediately after the
pair for the
T1
pair.
A1
G3 .
C3
16. Which of the following statements are TRUE? (may be more than one)
A. Ribosomes are large RNA structures composed solely of rRNA.
B. Ribosomes are synthesized entirely in the cytoplasm.
C. Each ribosome can bind to only one mRNA at a time.
D. Each mRNA can be translated simultaneously by multiple ribosomes.
Biol 131
Question Bank
Genes
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17. In Step A of the diagram to the right, a new tRNA has just arrived in a ribosome that is actively translating a
protein. In the diagram labeled Step B, redraw the tRNAs, (labeled as T1
and T2) showing the elongating AA chain (labeled 1 - 4) as they would
appear immediately after the next peptide bond forms. Be sure to show
the AA chain bonded to the correct tRNA.
18. Bacteria can be genetically engineered to make human insulin. How is this possible?
A. The human insulin gene exists naturally in bacteria.
B. The human insulin gene is a mutated form of a bacterial gene for bacterial insulin.
C. Since the genetic code is nearly universal, the bacterium is able to produce human insulin.
D. The engineered insulin is slightly different due to differences in the genetic code between eukaryotes
and prokaryotes
19. Many antibiotics (such as erythromycin) inhibit bacterial growth by blocking protein synthesis.
A. With which component of the cytoplasm would you expect these antibiotics to interact?
________________________
B. Explain why antibiotics like erythromycin can inhibit protein synthesis in bacteria but not that of the
humans (or other eukaryotes)? (Hint: what is an in important difference in the structure of a cellular
component of prokaryotes vs eukaryotes?)
Biol 131
Question Bank
Genes
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