Ch 13 - Practice Test
How many bases are in a codon?
3
How many consecutive mRNA bases are needed to specify an amino acid?
3
As seen in this figure, how many exons were used to assemble the pre-mRNA sequence, and how many exons were used in the finished mRNA?
3; 3
Suppose one strand of a "mini-gene" has the base sequence TACCCGGATTCA. If we assume no introns are involved, how many amino acids does the polypeptide encoded by this gene have?
4
What is the total number of different possible combinations of bases in a codon?
64
If a bacterial protein is made from 30 amino acids, how many nucleotides are needed to code for its production?
90
A tRNA that carries a specific amino acid enters the protein-synthesizing machinery at the ribosomes and pairs with the appropriate
codon
A sequence of three RNA bases can function as a(n)
codon or anticodon
Both DNA and RNA
contain phosphate groups
All of the following are directly involved in translation EXCEPT A) amino acids. B) DNA. C) ribosomes. D) tRNA. E) mRNA.
B) DNA
Which of the following has two polynucleotide strands? A) Messenger RNA B) DNA C) Ribosomal RNA D) RNA polymerase E) Transfer RNA
B) DNA
Which of the following is TRUE regarding gene expression? A) Different individuals of the same species express all of the same genes. B) Different tissues within an organism express different genes. C) Gene expression is not influenced by the environment. D) Gene expression remains constant throughout an organism's life span.
B) Different tissues within an organism express different genes.
Which of the following molecules transfers information from the nucleus to the cytoplasm? A) Lipids B) Proteins C) mRNA D) DNA E) tRNA
C) mRNA
The "one-gene, one-enzyme" hypothesis concluded that
each allele codes for a single type of protein
A mutation that results in a change in the codon-reading pattern could result from
either an insertion or a deletion of a base
For a mutation to affect the evolution of an animal species, it must occur within
gametes
Compare and contrast the three major RNA molecules involved in translation.
mRNA, tRNA, and rRNA are all single-stranded RNA molecules transcribed from DNA that play distinct roles in the translation process. mRNA carries information from the DNA molecule for the sequence of amino acids for the polypeptide. tRNA carries the amino acids that correspond to specific codon units (on the mRNA via its anticodon). rRNA molecules are important subunits of the ribosome, which is the site of translation.
Based on this table, which polypeptide would be synthesized from the mRNA base sequence AUGCCUGACUUA?
met-pro-asp-leu
What is an advantage to an organism producing microRNA?
microRNA can protect against viral infections.
A gene mutation is defined as change in the
nucleotide sequence of DNA
In the fungus Neurospora, a metabolic pathway synthesizes the amino acid Z (which is essential for its survival) from the precursor W. The intermediates X and Y are also produced in this pathway. The enzymes E1, E2, and E3 catalyze three reactions in the process, as follows: E1 E2 E3 W→ X → Y → Z X-ray radiation can be used to create a mutant strain of Neurospora that has a defective gene sequence for E2.Based on this scenario, the mutant strain will survive on media that contain
only Y or Z
In the intestinal bacteria Escherichia coli, the DNA segment that contains the coding for the enzymes of lactose metabolism is called the lactose ________.
operon
A transcription start signal is called a(n)
promoter
Ribosomes are a collection of
proteins and small RNAs that function in translation
The genetic code is
read in sets of three bases called codons.
A random change in a DNA nucleotide base sequence
represents a mutation
Transcription is the process of
synthesizing an RNA molecule using a DNA template
The strand of the DNA molecule that is transcribed is called the ________ strand.
template
In eukaryotes, a promoter that signals the beginning of the gene and binds with the promoter typically consists of
the bases TATAAA and response elements
Gene expression is a term that relates to
the flow of genetic information from DNA to proteins.
The process of copying genetic information from DNA to RNA is called
transcription
In eukaryotic cells, ________ occurs in the nucleus, resulting in the production of mRNA, which then travels to the ribosome for ________ into an amino acid chain.
transcription; translation
The type of RNA that binds to a specific amino acid is
transfer RNA
The manufacture of proteins from RNA and amino acids is referred to as
translation
The process of converting the "message" of mRNA into a sequence of amino acids is called
translation
The function of the promoter is to signal the RNA polymerase
where to start transcribing the DNA.
Which point mutation would be most likely to have a catastrophic effect?
A base deletion near the start of the coding sequence
Which of the following is noted when comparing DNA and RNA? A) Adenine pairs with different bases in DNA and RNA. B) No sugar is present in either molecule. C) Hydrogen bonding is important only in DNA. D) Thymine pairs with different bases in DNA and RNA. E) Only DNA has a backbone made up of sugars and phosphates.
A) Adenine pairs with different bases in DNA and RNA.
Suppose one strand of a "mini-gene" has the base sequence TACCCGGATTCA. The last codon in the mRNA sequence will be
AGU
Determine the sequence of bases in mRNA if the original DNA base sequence is TAGGCTAA.
AUCCGAUU
If the sequence of bases in a section of DNA is TAGGCTAA, what is the corresponding sequence of bases in mRNA?
AUCCGAUU
A "mini-gene" has the base sequence TACCCGTGCACG. If the T at the beginning of the sequence is deleted, what will be the consequence?
All of the codons after that point will be changed.
Which of the following has anticodons? A) RNA polymerase B) Transfer RNA C) Ribosomal RNA D) DNA E) Messenger RNA
B) Transfer RNA
A "mini-gene" has the base sequence TACCCGTGCACG. Which of the following sequences represents a single base substitution? A) TACCCGTGCACG B) TACCCGTGTCACG C) TACCCGAGCACG D) TACCGTGCTACG E) TACCCGGCACG
C) TACCCGAGCACG
In females, an entire X chromosome is inactivated in each cell. The inactivated X chromosome is called the ________.
Barr Body
Which of the following binds to codons? A) RNA polymerase B) DNA C) Transfer RNA D) Messenger RNA
C) Transfer RNA
Which of the following contains deoxyribose? A) Transfer RNA B) RNA polymerase C) DNA D) Ribosomal RNA E) Messenger RNA
C) DNA
Which of the following is found in RNA but NOT in DNA? A) Deoxyribose B) Thymine C) Uracil D) Phosphate groups E) Adenine
C) Uracil
Which of the following occurs in the nucleus? A) Translation only B) Transcription only C) Replication of genetic material only D) Both transcription and replication of genetic material E) Both translation and replication of genetic material
D) Both transcription and replication of genetic material
Which of the following contains codons? A) Transfer RNA B) Ribosomal RNA C) DNA D) Messenger RNA E) RNA polymerase
D) Messenger RNA
Which statement correctly describes transcription? A) RNA chains of different genes can be transcribed from either DNA strand, with RNA polymerase traveling from the 5' end and moving toward the 3' end. B) RNA chains of all genes are synthesized from the same DNA strand, with the growing RNA strand always starting at the 5' end and moving toward the 3' end. C) RNA chains of all genes are synthesized from the same DNA strand, with the growing RNA strand always starting at the 3' end and moving toward the 5' end. D) RNA chains of different genes can be transcribed from either DNA strand, with RNA polymerase traveling from the 3' end and moving toward the 5' end.
D) RNA chains of different genes can be transcribed from either DNA strand, with RNA polymerase traveling from the 3' end and moving toward the 5' end.
Which of the following synthesizes RNA molecules in the nucleus? A) Transfer RNA B) Ribosomal RNA C) Messenger RNA D) RNA polymerase E) DNA
D) RNA polymerase
Which of the following has the fewest nucleotides in its strand? A) mRNA, having 50 codons B) Protein, having 40 amino acids C) mRNA, having 100 bases D) mRNA, having 75 nucleotides E) Protein, with 2 polypeptides, each having 35 amino acids
D) mRNA, having 75 nucleotides
The sequence of nitrogen-containing bases on one strand of DNA could determine all of the following EXCEPT the sequence of A) nitrogen-containing bases in the other DNA strand. B) nitrogen-containing bases in mRNA. C) amino acids in a protein molecule. D) ribose and phosphate molecules in tRNA.
D) ribose and phosphate molecules in tRNA
Which of the following attaches to specific amino acids? A) Ribosomal RNA B) Messenger RNA C) RNA polymerase D) DNA E) Transfer RNA
E) Transfer RNA
Which of the following contains four types of nucleotides but no uracil?
DNA
Which of the following molecules function to transfer genetic information from one generation to the next? A) tRNA B) Protein molecules C) Lipid molecules D) mRNA E) DNA
E) DNA
Which of the following is NOT a means of regulating gene expression? A) Regulating how long a protein lasts in a cell B) Modifying proteins after they are synthesized C) Varying the rate at which messenger RNAs are translated D) Varying the rate at which messenger RNAs are transcribed E) Deleting genes from cells in which they are not needed
E) Deleting genes from cells in which they are not needed
Which of the following is a protein made up of amino acids? A) Transfer RNA B) DNA C) Uracil D) Messenger RNA E) RNA polymerase
E) RNA polymerase
Each ribosome is specific for a particular type of protein.
False
The Barr body is the X chromosome in the cell that is expressed, whereas the other X chromosome is inactivated.
False
tRNA is necessary for transcription to occur.
False
Describe the three basic steps or processes involved in transcription.
First, initiation involves RNA polymerase binding to a specific promoter region on the template strand of the DNA molecule. Second, elongation involves RNA polymerase moving along the DNA template strand and adding the appropriate complementary RNA nucleotides. Third, termination occurs when the RNA polymerase reaches a termination signal on the DNA template strand, and the new mRNA is released to move onto the cytoplasm.
If a tRNA molecule that is specialized for the transfer of the amino acid valine has the anticodon CAG, it will couple with the codon
GUC
What does mRNA carry away from the nucleus?
Information
A random change in the DNA nucleotide base sequence is called a ________.
Mutation
Which of the following is NOT a theory of epigenetics explaining how cells can change gene function without changing the DNA base sequence?
Mutations causing new beneficial alleles
A mutation in which one nucleotide in the DNA sequence is substituted for another nucleotide is referred to as a ________ mutation.
Point
Imagine that the short DNA base sequence GGCTGC is transcribed and then translated by a ribosome. The following activated tRNA molecules are available in the cytoplasm: tRNA Anticodon Amino Acid GGC proline CGU alanine UGC threonine CCG glycine ACG cysteine CGG alanine What resulting dipeptide will form?
Proline-threonine
The genetic material of some viruses, such as HIV, is not DNA but is instead
RNA
List three ways in which an RNA molecule differs from a DNA molecule.
RNA is normally single-stranded, whereas DNA is double-stranded. RNA has the sugar ribose, whereas DNA has deoxyribose. RNA uses the base uracil, whereas DNA uses thymine.
How can RNA be distinguished from DNA?
RNA is single-stranded
What is the site of protein synthesis in the cell?
Ribosome
What kind of mutation occurs when one base is changed to another at a single location in the DNA?
Substitution
How can a single gene code for more than one protein?
The exons within an mRNA can be spliced together in different ways.
In a wild-type strain of fruit flies, the length of a gene from the start to the stop codon is 2,000 DNA bases. Suppose an experiment indicated that the mRNA molecule transcribed from this gene is much shorter (only 1,200 bases). What is the most likely explanation for this?
There are introns in the DNA that were cut out of the mRNA.
What is an anticodon?
Three consecutive bases in tRNA
What molecule is responsible for translation of the four-letter "nucleic acid language" (A, T, G, and C nucleotides) into the 20 "amino acid language" of proteins by bringing in amino acids to the ribosome?
Transfer RNA
A codon of mRNA consists of three bases that code for an amino acid.
True
In general, each gene codes for a specific protein.
True
Messenger RNA is single-stranded.
True
Steroid hormones have the ability to regulate transcription.
True
The site of protein synthesis in the cytoplasm is the ribosome.
True
Suppose the template DNA strand of a "mini-gene" has the base sequence TACCCGGATTCA. The anticodon of the tRNA that carries the first amino acid to the ribosome will be
UAC
The anticodon for the codon AUC is ________.
UAG
What is the anticodon for AUC?
UAG
The fact that calico cats are only female supports the theory of
X-chromosome inactivation and Barr bodies in females.
A gene can be mutated with no resulting functional change in the protein that is produced from that gene if
a codon has changed, but it codes for the same amino acid as the original codon.
The nitrogenous base uracil pairs with
adenine
The sequence of nitrogen-containing bases on one strand of DNA most directly determines the sequence of
amino acids in a protein molecule
A tRNA molecule brings ________ to the ribosome during protein synthesis.
an amino acid
Transfer RNA
brings amino acids to the ribosome
Your tongue does NOT grow hair because
different genes are expressed in different tissues
