Chapter 10: Gene Expression and Regulation
Multiple Choice



1.  

Which of the following are accurate statements concerning the differences between DNA and RNA? (Level 1)

RNA is usually double-stranded, but DNA is usually single-stranded.
RNA has the sugar deoxyribose, but DNA has the sugar ribose.
RNA contains three different nucleotides, but DNA contains four different nucleotides.
RNA lacks the base thymine (which is found in DNA) and has uracil instead.


2.  

The process of RNA synthesis is called __________. (Level 1)

transcription
translation
replication
mutation


3.  

Information in DNA is carried in __________. (Level 1)

the sugar-phosphate backbone of one DNA strand
the base pairs between nucleotides in the two DNA strands
the proteins that bind to the DNA double helix
the order of the nucleotide bases in one DNA strand


4.  

Which of the following statements about the functions of RNA is correct? (Level 1)

The information for protein synthesis is carried by tRNA.
rRNA is an intermediate in the synthesis of mRNA.
rRNA is an important component of ribosomes.
Translation requires tRNA and mRNA, but not rRNA.


5.  

Which of the following correctly lists the items in order of their relative sizes? (Level 1)

nucleotide, codon, base pair, promoter, hemoglobin mRNA, hemoglobin gene, ribosome, chromosome
nucleotide, base pair, codon, promoter, hemoglobin gene, hemoglobin mRNA, ribosome, chromosome
nucleotide, base pair, codon, promoter, hemoglobin mRNA, hemoglobin gene, ribosome, chromosome
nucleotide, base pair, codon, promoter, hemoglobin mRNA, hemoglobin gene, chromosome, ribosome


6.  

Both transcription and translation occur in three steps. What happens during the elongation step of each process? (Level 1)

During the elongation step of transcription, the RNA molecule is synthesized. During the elongation step of translation, the protein molecule is synthesized.
During the elongation step of transcription, the RNA molecule is stretched out to full length. During the elongation step of translation, the protein molecule is stretched out to full length.
During the elongation step of transcription, synthesis of an RNA molecule is started. During the elongation step of translation, synthesis of a protein molecule is started.
During the elongation step of transcription, the mRNA molecule is completed. During the elongation step of translation, the protein molecule is completed.


7.  

The flow of genetic information in cells depends on specific base pairing between nucleotides. Which of the following correctly matches the type of base pairing with the process of translation? (Level 1)

In translation, RNA base-pairs with DNA.
In translation, RNA base-pairs with RNA.
In translation, tRNA base-pairs with rRNA.
In translation, tRNA base-pairs with mRNA.


8.  

During DNA replication, a mistake was made in which an A was changed to a G. This kind of mutation is called a(n) __________. (Level 1)

point mutation
insertion mutation
deletion mutation
neutral mutation


9.  

The DNA sequence of a codon in a gene was changed from AAT to AAC. This type of mutation is called a(n) __________. (Level 1)

point mutation
insertion mutation
deletion mutation
neutral mutation


10.  

The cells in your skin have a different shape and different function from the cells in your liver because the two types of cells have different __________. (Level 1)

DNA
proteins
lipids
carbohydrates


11.  

Which genes are expressed in a cell depends on the cellís __________. (Level 1)

environment
history
function
All of the above
All except one of the above answers are correct.


12.  

Which of the following is not a step at which gene expression can be regulated in eukaryotic cells? (Level 1)

The rate of transcription
The rate of translation
The rate of DNA replication
The types and rates of protein modification
The rate of enzyme activity


13.  

In mammals, males have one X chromosome and one Y chromosome and females have two X chromosomes. How is the expression of genes on the X chromosome regulated so that there is equal expression of genes on the X chromosome in males and females? (Level 1)

One X chromosome in females is inactivated so that females only have a single X chromosome capable of transcription.
The genes on the X chromosome in males are transcribed twice as fast as in females.
All of the X chromosomes are inactivated so that no genes are expressed from the X chromosome in either males or females.
The Y chromosome contains balancing genes that help to raise the levels of mRNA produced by the X chromosome in males.


14.  

Imagine that a codon in the template strand of a gene has the sequence TAC. What sequence of the anticodon would decode this codon? Explain your answer. (Level 2)

ATG, because the anticodon is complementary to the template strand
AUG, because the anticodon is complementary to the template strand
UAC, because the anticodon has the same sequence as the template strand (but it has U instead of T)
TAC, because the anticodon has the same sequence as the template strand


15.  

Certain genes, sometimes called house-keeping genes, are expressed in all cells in your body. Other genes are only expressed in certain specialized cells. Which of the following genes is likely to be a housekeeping gene? (Level 2)

Hemoglobin
Milk proteins
Ribosomal proteins
Insulin


16.  

Imagine that a probe sent to Mars brings back a sample that contains a very primitive life-form that appears similar to bacteria. Scientists are able to revive it and begin to grow it in culture. Much to their amazement, they discover that the organism has DNA and that the DNA encodes proteins. However, the DNA of these Martian microbes contains only two nucleotides, and these nucleotides contain bases that are not present in the DNA of organisms on Earth. If the Martian microbe uses triplet codons, what is the maximum number of different amino acids that it can have in its proteins? Explain. (Level 3)

9, because 32 = 3 x 3 = 9
16, because 42 = 4 x 4 = 16
8, because 23 = 2 x 2 x 2 = 8
6, because there are 8 possible codons (23 = 2 x 2 x 2 = 8) but at least one of the codons must be a start and one must be a stop


17.  

Sometimes an animal, including humans, has eyes of two different colors. What is a possible explanation for this trait? (Level 3)

A mutation occurred in the sperm that produced this individualís embryo.
A mutation occurred in the egg that produced this individualís embryo.
A chemical toxin inhibited production of pigment in one eye but not the other.
During early stages of development, a mutation occurred in the cell that developed into one of the eyes, but not other cells in the embryo.


18.  

How did Beadle and Tatum use genetic mutations in strains of Neurospora as an investigative tool?

They tested the hypothesis that a specific region of DNA (genes) could somehow encode a specific enzyme.
They crossed mutant strains that required a specific dietary supplement to survive with normal Neurospora.
They showed that strains with a dietary supplement requirement were defective in one or another enzyme in the biochemical synthetic pathway for that supplement but never to more than one enzyme from the same biochemical pathway.
All of the above


19.  

mRNA is produced from DNA via

Replication
Transcription
Translation
Protein synthesis


20.  

The "genetic code" includes

Units of three bases, each triplet (or codon) corresponding to a single amino acid
Specific base sequences in the nucleic acids that indicate where to "begin" and "end" the synthesis of a polypeptide
Only two bases per amino acid
The first two answers are correct.


21.  

What is the promoter region?

It is a region of RNA that binds to the RNA polymerase and initiates transcription.
It is a component of each type of RNA.
It is responsible for the selective nature of transcription.
It is a region of a parent DNA strand that binds to the RNA polymerase and initiates transcription.


22.  

Which of the following is the first step in translation?

Bases of the tRNA anticodon bind with the bases of the mRNA codon.
The formation of a peptide bond between amino acids attached to the adjacent tRNAs on the ribosome.
The ribosomal subunits are disassembled.
Stop codons on the mRNA bind to special proteins rather than tRNA molecules.


23.  

Regulation of genetic expression

Involves a limited number of molecules and steps and has been well understood for some time
Can be influenced by environmental conditions, including temperature changes
Can occur at any point during replication, transcription, or translation and involves many, many different molecules
Both the second and third answers above are correct.


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