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Bio Final Exam
Terms in this set (100)
Who formulated the one gene-one enzyme hypothesis?
Beadle and Tatum
During Griffith's experiments with Streptococcus pneumoniae in mice, material from __________ bacteria transformed __________ bacteria.
heat-killed pathogenic ... living nonpathogenic
Avery and his colleagues' 1944 experiment showed that DNA
was the substance that transformed the bacteria in Griffith's experiment
A scientist assembles 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
In an important experiment, a radioactively labeled bacteriophage was allowed to infect bacteria. In a first trial, the phage contained radioactive DNA, and radioactivity was detected inside the bacteria. Next, phage-containing radioactive protein was used, and the radioactivity was not detected inside the bacteria. These experiments led to the conclusion that __________.
the genetic material of the phage is DNA
Until Hershey and Chase showed that DNA was the genetic molecule of the phages they studied, what class of molecules was considered the best candidate for carrying genetic information and why?
proteins because they were thought to be the only molecule with both the variety and specificity of function to account for the array of heritable traits observed
Monomers for the synthesis of DNA are called
Chargaff found that for DNA _
the ratio of A to T is close to 1:1 and the ratio of G to C is close to 1:1
Which of the following techniques was most helpful to Watson and Crick in developing their model for the structure of DNA?
In DNA, the two purines are __________, and the two pyrimidines are __________.
adenine and guanine ... cytosine and thymine
Which one of the following statements is correct?
Adenine forms two hydrogen bonds with thymine; guanine forms three hydrogen bonds with cytosine.
The two antiparallel strands of nucleotides that form the DNA double helix are held together by __________.
hydrogen bonds between nucleotide bases
The information in DNA is contained in
the sequence of nucleotides along the length of the two strands of the DNA molecule
Who is credited with explaining the structure of the DNA double helix?
Watson and Crick
Which of the following attributes of DNA is most crucial to its accurate duplication?
its specific base pairing through hydrogen bonds
During the replication of DNA, __________
both strands of a molecule act as templates
The experiments of Meselson and Stahl showed that DNA
replicates in a semiconservative fashion
Which of the following statements about replication origins is/are correct?
The DNA sequence at the origin of replication is recognized by specific proteins that bind to the origin.
The two strands of DNA at the origin of replication are separated, creating a replication bubble.
Bacterial chromosomes have a single origin of replication, but eukaryotic chromosomes have many origins.
Replication proceeds in both directions from each origin.
At each end of a DNA replication bubble is
a replication fork
The role of DNA polymerases in DNA replication is to _
attach free nucleotides to the new DNA strand
In prokaryotes, the rate of elongation during DNA replication is __________ the rate in eukaryotes.
much faster than
The two strands of a DNA double helix are antiparallel. This means that __________.
one strand runs in the 5' to 3' direction, and the other runs in the 3' to 5' direction
One strand of a DNA molecule has the base sequence 5′-ATAGGT-3′. The complementary base sequence on the other strand of DNA will be 3′- __________-5′
DNA polymerase adds nucleotides to the __________ of the leading strands, and to the __________ of the lagging strands (Okazaki fragments).
3′ end ... 3′ end
What enzyme joins Okazaki fragments?
After the formation of a replication bubble, which of the following is the correct sequence of enzymes used for the synthesis of the lagging DNA strand?
helicase, primase, DNA polymerase, ligase
Which of the following components is required for DNA replication?
The removal of the RNA primer and addition of DNA nucleotides to the 3' end of Okazaki fragments in its place is carried out by _
DNA polymerase I
The unwinding of DNA at the replication fork causes twisting and strain in the DNA ahead of the fork, which is relieved by an enzyme called __________.
Once the DNA at the replication fork is unwound by helicases, what prevents the two strands from coming back together to re-form a double helix?
Single-strand binding proteins bind the unwound DNA and prevent the double helix from re-forming.
Which one of the following statements regarding DNA replication is correct?
Helicases separate the two strands of the double helix, and DNA polymerases then construct two new strands using each of the original strands as templates.
As a result of proofreading by DNA polymerases, the overall error rate in the completed DNA molecule is approximately
1 error per 10,000,000,000 nucleotides
The incorporation of an incorrect base into the DNA during replication
can be repaired by the mismatch repair system
Which set of enzymes is involved in nucleotide excision repair?
nuclease, DNA polymerase, and ligase
Which of the following statements is/are correct with regard to individuals with the disorder xeroderma pigmentosum?
Cells in these individuals have difficulty repairing thymine dimers.
These individuals are extremely sensitive to sunlight.
These individuals have high rates of skin cancer.
These individuals usually have inherited defects in the nucleotide excision repair system.
Unlike prokaryotic DNA replication, replication of eukaryotic chromosomes
cannot be completed by DNA polymerase
get shorter with each round of DNA replication
is an enzyme that lengthens telomeres
In a comparison between asexually reproducing bacteria and sexually reproducing multicellular eukaryotes, uncorrected errors in replication are more likely to be transmitted to subsequent generations in bacteria than in multicellular eukaryotes. Which of the following provides the best evidence-based explanation for this difference?
Because they are asexual and single-celled, all uncorrected errors of replication in bacteria are transmitted to subsequent generations. Multicellular eukaryotes typically reproduce sexually, so uncorrected errors are transmitted only if they occur in germ cells that meiotically divide to produce gametes.
What is the major difference between bacterial chromosomes and eukaryotic chromosomes?
Bacteria usually have a single circular chromosome whereas eukaryotes have several linear chromosomes.
Which of the following considerations was/were important in the choice of viruses and bacteria for early experiments on DNA?
They have short generation times.
Their chromosomes have a simpler structure.
They can interact with each other.
They typically have relatively small genomes.
In the "beads on a string" structure of unfolded chromatin, the "beads" are __________.
Genetic information of eukaryotic cells is transferred from the nucleus to the cytoplasm in the form of
Which statement is true
Each amino acid in a protein is coded for by three bases in the DNA.
When RNA is being made, the RNA base __________ always pairs with the base __________ in DNA.
Generally speaking, how many genetic codes are there?
The number of nucleotide bases "read" together on the mRNA to designate each amino acid is __________; this unit is called a(n) __________.
three ... codon
The codons AAA, CCC, GGG, and UUU specify the amino acids lysine, proline, glycine, and phenylalanine, respectively. If the base sequence 5′-CCCAAATTTGGG-3′ is present in the coding strand of a stretch of DNA, what polypeptide sequence would be encoded by the corresponding template strand?
How many nucleotides are needed to code for a protein with 450 amino acids
at least 1,350
In many cases, more than one codon codes for the same amino acid. Because of this, we say that the code is
Bacteria can transcribe and translate human genes to produce functional human proteins because
the genetic code is nearly universal
In a eukaryotic cell, transcription takes place
in the nucleus
What catalyzes the linkage between ribonucleotides to form RNA during gene expression?
One strand of a DNA molecule has the following sequence: 3′-AGTACAAACTATCCACCGTC-5′. In order for that strand to be transcribed, there would have to be a specific recognition sequence, called a(n) __________, to the left of the DNA sequence indicated.
In transcription, __________.
the promoter region acts as an initial binding site for RNA polymerase
only one of the DNA strands is used as the template
the RNA nucleotides used are produced by the cell
Which statement is false?
In bacteria, proteins called transcription factors enhance the affinity of RNA polymerase to the promoter sites of genes.
In eukaryotes, which mechanism operates after transcription, but before translation of mRNA into protein?
Which accurately describes the usual process of eukaryotic transcription?
Both introns and exons are transcribed, but the RNA transcribed from introns does not leave the nucleus.
Which statement correctly describes mRNA processing?
Introns are cut out of the primary transcript, and the resulting exons are spliced together.
Two different proteins with mostly different structures are translated from two different mRNAs. These mRNAs, however, were transcribed from the same gene. Which mechanism could best account for this
Exons from the same gene could be spliced in different ways to make different mRNAs.
What is a key difference between eukaryotic and prokaryotic gene expression
In prokaryotic cells, the RNA transcript is immediately available as mRNA without processing.
At one point, as a cell carried out its day-to-day activities, the nucleotides GAT were paired with the nucleotides CUA. This pairing occurred
The function of tRNA during protein synthesis is to
deliver amino acids to their proper site during protein synthesis
Which summary of protein synthesis is correct
Messenger RNA is made on a DNA template, and then amino-acid-bearing transfer RNAs bind to the mRNA through codon-anticodon pairing.
The bonds that hold tRNA molecules in the correct three-dimensional shape are __________.
During translation in a eukaryotic cell,
polypeptides are synthesized at ribosomes, according to instructions carried by mRNA
The P site of a ribosome does which of the following?
It holds the tRNA carrying the growing polypeptide chain.
The first amino acid inserted into a new polypeptide chain in eukaryotic cells is usually
Which is a post-translational modification of a polypeptide
cleavage of a polypeptide into two or more chains
During translation, amino acid chain elongation occurs until
the ribosome encounters a "stop" codon
Polysomes may be defined as
groups of ribosomes translating the same mRNA
Cells are able to distinguish proteins destined for secretion or for segregation to specific intracellular compartments from those that will remain in the cytoplasm because
some proteins, as they begin to be synthesized, contain a signal region that causes the ribosome with its growing polypeptide to attach to the ER and translocate the polypeptide into the lumen (space) of the ER
What is their proper sequence for these steps? 1. translation 2. RNA processing 3. transcription 4. modification of protein
3 2 1 4
The mRNA codons 5′-CAA-3′ or 5′-CAG-3′ are translated as the amino acid glutamine by
the same tRNA with the anticodon 3′-GUU-5′
Which statement regarding the structure and function of tRNA is false?
Although each tRNA consists of a relatively short, single RNA strand, this single strand can achieve a three-dimensional structure by folding back upon itself and forming covalent bonds between complementary bases.
A particular mutation had no effect on the polypeptide encoded by a gene. This mutation probably involves
a silent or neutral mutation
Which type of mutation is least likely to affect protein function?
A virus infects a cell and randomly inserts many short segments of DNA containing a stop codon throughout an organism's chromosomes. This will probably cause
manufactured proteins to be short and defective
A point mutation in which a single base pair is inserted or deleted from DNA is called a(n)
Ultraviolet (UV) radiation is damaging to cells because it
causes mutations in the DNA
Darwin originally defined evolution as
descent with modification
Which of the following is a key observation that must be explained in a unifying theory about life?
Many basic characteristics are shared by all living things.
The scala naturae, or scale of nature, is based on the ideas of
At the time Darwin voyaged on HMS Beagle, the popularly accepted theory in Western culture that explained the origin of Earth's plants and animals held that the various species __________.
had been created by divine intervention a few thousand years before
Carolus Linnaeus is considered to be the founder of __________, and he _________
the binomial classification system ... thought that resemblances among different species reflected the pattern of their creation
The modern idea of extinction as a common occurrence in Earth's history was first proposed in the early 19th century writings of __________.
Lyell's principle of uniformitarianism
strongly influenced Darwin's view of how living organisms could change over time
Which of the following is a true statement about Charles Darwin?
He proposed natural selection as the mechanism of evolution.
At the time Charles Darwin sailed on HMS Beagle,
several biologists had proposed that species might change over time, but none had suggested a convincing mechanism that might cause the change
Because he was well aware of the effect his theory of evolution would have on the public and on the Church of England, Darwin delayed publishing his work for several decades while he gathered additional evidence. After invoking selective breeding of domesticated species as evidence that groups of organisms are capable of change, he then proposed that natural populations can change as well. On which two lines of evidence did he base this proposal?
Organisms within a population vary, and all populations produce more offspring than can be supported by the environment, resulting in competition for survival within the population.
During his voyage around the world, Darwin was inspired to think about evolution by
fossils he collected
the unique organisms he saw in the Galápagos Islands
the works of others such as Lamarck
studying adaptations of organisms to their environments
In Darwin's view of descent with modification
natural selection can improve the match between an organism and its environment
What insight did Darwin gain from reading Thomas Malthus's essay on human suffering?
Organisms have the capacity to produce more offspring than the environment can support.
The breeding of plants and animals for particular traits by humans is called
During periods of rapid environmental change, what may happen to a species that was well-suited to the former environment?
The species may go extinct.
The population may change so much in adapting to the new environment that it is considered a new species.
Individuals with particular traits that provide an advantage in the new environment will have higher reproductive success.
Traits that were favorable in the original environment may be detrimental in the new environment.
The smallest unit that can evolve is
Which of the following is an example of the process of evolution
According to the theory of evolution, anatomical and molecular homologies should
produce similar patterns of evolutionary relatedness
When they were first sold, aerosol insecticides were highly effective in killing flies and mosquitoes. Now, several decades later, a much smaller proportion of these insects die when sprayed. The reason fewer insects die when they are sprayed is that
many mosquitoes today are descendants of mosquitoes with insecticide-resistant characteristics
A population of zooplankton is exposed to a small number of predatory fish that feed on the larger-sized (adult) zooplankton. Which of the following predictions would most likely occur based on the principles of natural selection?
The population will come to contain adult zooplankton that reach sexual maturity when they are still relatively small.
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