Biology 156, Unit 13 Self-Test

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Why are viruses not considered to be living things?: they are unable to reproduce on their own, and can only survive and reproduce by infecting a living cell
Viruses that infect bacteria are called:: bacteriophages
The experiments by Hershey and Chase included:: both A and C are correct
A. using radioactive sulfur to label the proteins in viruses
C. finding that DNA was the genetic material of the virus they studied
When a bacteriophage infects a bacterium, what part of the phage enters the bacterial cytoplasm?: only the DNA
The basic monomer units of DNA and RNA are:: nucleotides
A nucleotide is made of which of the following chemical components?: a nitrogenous base, a phosphate group, and a sugar
RNA contains ___, while DNA contains ___.: ribose, deoxyribose
Which of these nitrogenous bases is found only in RNA?: uracil
Which of these nitrogenous bases is found only in DNA?: thymine
Watson and Crick explained "Chargaff's rules" in DNA by showing that:: C always pairs with G
Watson and Crick were the first to correctly describe the structure of DNA as:: a double helix
In the DNA molecule, what molecules compose the sides of the "ladder?": phosphate and sugar
Complementary bases on opposite sides of the DNA molecule are held together by:: hydrogen bonds
If one strand of a DNA molecule has a nucleotide sequence of GCTTAGCAA, what is the complementary sequence for the other strand?: CGAATCGTT
Which of the following correctly describes DNA replication?: All of the Above

A. DNA replication begins at specific sites, called origins of replication.
B. Replication proceeds in both directions, creating what are called replication "bubbles."
C. The DNA molecule has many origins where replication can start simultaneously, so that thousands of bubbles can be present at once.
Which of the following is a function of DNA polymerases?: all of the above
A. They covalently connect the nucleotides to form a new strand as the nucleotides line up along an existing strand.
B. They perform a proofreading step that quickly removes nucleotides that have base-paired incorrectly during replication.
C. They repair DNA damaged by harmful radiation or toxic chemicals.
The "one gene - one polypeptide" theory states that:: the function of an individual gene is to dictate the production of a specific polypeptide
The transfer of genetic information from DNA into an RNA molecule is called:: transcription
The transfer of the information in the RNA into a protein is called:: translation
Where does translation take place in eukaryotic cells?: cytoplasm
Where does transcription take place in eukaryotic cells?: nucleus
Which of the following sequences best describes the flow of information that takes place when a gene directs the synthesis of a cellular component?: DNA, RNA, protein
In protein synthesis, transcription involves the language of:: nucleotide bases
There are ___ different bases in DNA, and ___ different amino acids in proteins.: 4, 20
In translation, how many nucleotide bases are used to determine each amino acid to be placed into a polypeptide?: 3
A group of three nucleotide bases is called: a codon
How many different codon combinations are there?: 64
The DNA codon AUG means:: both A and B are correct
A. add the amino acid methionine
B. start a polypeptide chain here
Translation of codons to amino acids is ___, but not ___.: redundant, ambiguous
For a strand of DNA with a sequence of GATTCGCCA, what is the complementary strand of mRNA?: CUAAGCGGU
For a strand of mRNA with a sequence of AUGGUAGCCCAU, what is the polypeptide that is produced?: Met-Val-Ala-His
Which of the following is the enzyme that links together the nucleotides in an RNA molecule?: RNA polymerase
The signal that marks the beginning of a gene, and causes transcription to start is:: a promoter
The signal that marks the end of a gene, and causes transcription to stop is: a terminator
Which of the following occurs when RNA polymerase attaches to the promoter DNA?: initiation of a new RNA molecule
Which of the following is a type of mRNA processing that occurs after transcription, but before the mRNA leaves the nucleus?: both A and B are correct
A. addition of a small cap and long tail of additional nucleotides
B. removal of introns
The addition of a small cap and long tail on mRNA is:: only B and C are correct
B. to protect the mRNA from enzymes
C. to help the ribosomes recognize the mRNA
Regions of noncoding DNA within a gene are called:: introns
The coding regions of a gene (the portions that are expressed as polypeptide sequences) are called:: exons
RNA splicing involves the:: removal of introns from the molecule
Which of the following recognizes codons in mRNA and brings in the appropriate amino acid?: tRNA
The area of the tRNA molecule that couples the tRNA to the mRNA is called the:: anticodon
What is the function of a ribosome?: hold mRNA and tRNA together, and connect amino acids
Which of the following is required for translation to occur: all of the above
A. mRNA
B. tRNA
C. ATP
D. ribosomes
Which of the following is required for translation to occur?: all of the above
A. a supply of amino acids
B. enzymes for attaching amino acids to tRNA
C. rRNA
D. energy
mRNA attaches to the ___ of a ribosome, and tRNA attaches to the ___ of a ribosome.: small subunit, large subunit
Any change in the nucleotide sequence of the DNA of a gene is called:: a mutation
A base substitution mutation in a gene sometimes has no effect on the protein the gene codes for. Which of the following factors could account for this?: the redundancy of the genetic code
What is the result of a base insertion or deletion?: a shift in the reading frame of the nucleotide sequence
A base ___ is usually far more harmful than a base ___.: deletion or insertion, substitution
A physical or chemical agent that changes the nucleotide sequence of DNA is called:: a mutagen
How can a virus perpetuate its genes without destroying the host cell?: by inserting the viral DNA into a chromosome of the host cell, then allowing the host to replicate the entire chromosome
Which of the following are RNA viruses?: only A and B are correct
A. measles and mumps
B. AIDS and polio
Which of the following are DNA viruses?: hepatitis and chicken pox
When an RNA virus infects a host cell, what can be done with the viral RNA?: all of the above
A. the RNA can be used to make proteins
B. the RNA can be duplicated to make new viruses
C. in retroviruses, the RNA can serve as a template to make DNA
Which of the following statements is true?: a vaccine can often be used to help a person develop immunity to a viral infection before exposure to it
How can viruses enter plant cells?: all of the above
A. through lesions caused by injuries
B. through transfer by insects that feed on the plants
C. through contaminated farming or gardening tools
Why do RNA viruses tend to have an unusually high rate of mutation?: The replication of RNA from RNA viruses does not involve the proofreading steps of DNA replication
The high rate of mutation of RNA viruses results in:: all of the above
A. new varieties of influenza that can cause disease in people who had immunity to the old varieties
B. periodic flu epidemics
C. difficulty in producing a flu vaccine that provides guaranteed immunity
An RNA virus (like HIV) that reproduces by means of a DNA molecule is a:: retrovirus
Which of the following is the enzyme that HIV uses to synthesize DNA on an RNA template?: reverse transcriptase
Scientists have discovered how to put together a bacteriophage with the protein coat of phage T2 and the DNA of phage T4. If this composite phage were allowed to infect a bacterium, the phages produced in the host cell would have ______.: the protein and DNA of T4
A geneticist found that a particular mutation had no effect on the polypeptide coded by a gene. This mutation probaboy involved: substitution of one nucleotide
Which of the following correctly ranks the structures in order of size, from largest to smallest?: chromosome-gene-codon-nucleotide
The nucleotide sequence of a DNA codon is GTA. A messenger RNA molecule with a complementary codon is transcribed from the DNA. In the process of protein synthesis, a transfer RNA pairs with the mRNA codon. What is the nucleotide sequence of the tRNA ant: GUA

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