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163 Cards in this Set

  • Front
  • Back
Who formulated the one gene–one enzyme hypothesis?
Beadle and Tatum
Genetic information of eukaryotic cells is transferred from the nucleus to the cytoplasm in the form of _____
rna
Which of the following statements 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.
U...A
Generally speaking, how many genetic codes are there?
one
Correct. Although slight variations do exist, the genetic code is universal. Nearly all organisms use the same genetic code to translate mRNA to protein.
What mRNA codon would be made from the DNA triplet CGT?
GCA
The number of nucleotide bases "read" together on the mRNA to designate each amino acid is _____; this unit is called a(n) _____.
three...codon
In many cases, more than one codon codes for the same amino acid. Because of this, we say that the code is _____.
redundant
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
Which of the following best describes the arrangement of genetic information in a DNA molecule?
the three-nucleotide words of a gene are arranged in a nonoverlapping series on the DNA template strand.
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 _____
during transcription
Which of the following catalyzes the linkage between ribonucleotides to form RNA during gene expression?
RNA polymerase
In eukaryotic cells, a terminator in mRNA synthesis is
a specific nucleotide sequence in DNA that signals the RNA polymerase to stop
During the transcription of a given portion of a DNA molecule _____.
mRNA is synthesized on only one of the chains
n eukaryotes, which of the following mechanisms of gene regulation operates after transcription, but before translation of mRNA into protein?
RNA splicing
Which of the following accurately describes the usual process of transcription for eukaryotic genes?
Exons are transcribed, but the RNA transcribed from introns does not leave the nucleus.
Which of the following statements correctly describes mRNA processing?
Introns are cut out of the primary transcript, and the resulting exons are spliced together.
the structures called snRNPs are _____
part of splicesomes
Nuclei of eukaryotic cells contain spliceosomes that are made up of ____
snRNA and protein
The function of tRNA during protein synthesis is to _____
deliver amino acids to their proper site during protein synthesis
Which of the following summaries of protein synthesis is correct?
Messenger RNA is made on a DNA template, and then amino-acid-bearing transfer RNAs bind to it through codon-anticodon pairing.
The bonds that hold tRNA molecules in the correct three-dimensional shape are _____.
hydrogen bonds
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 _____.
methionine
Which of the following 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
What is the proper order of the following events in the expression of a eukaryotic gene?
1. translation
2. RNA processing
3. transcription
4. modification of protein

3, 2, 1, 4
A geneticist found that a particular mutation had no effect on the polypeptide encoded by the gene. This mutation probably involved _____
a silent or neutral mutation
A base-pair substitution mutation in a germ cell line is likely to have no effect on phenotype if the substitution _____.
occurs in an intron
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) _____.
frame-shift mutation
Transcription factors are found in _____
archaea and eukaryotes
On the off chance that you might contract an archaeal infection, how might it be treated?
None of the listed responses is correct.
When genes are expressed, they produce _____.
The second and fourth responses are correct.
When lactose is present, it binds to the repressor and changes its shape.
As a result of this change, the repressor can no longer bind to the operator region. RNA polymerase can then bind to the promoter and transcribe the lac genes.
When the enzymes encoded by the lac operon are produced, they break down what and do what?
lactose, eventually releasing the repressor to stop additional synthesis of lac mRNA.
In prokaryotic genomes, groups of functionally related genes along with their promoters and operators are found together in _____.
an operon
In general, operons that encode the enzymes of a biosynthetic (anabolic) pathway (such as the trp operon) are _____, and those encoding the enzymes of a catabolic pathway (such as the lac operon) are _____.
repressible ... inducible
In an inducible operon, the inducer is often the _____ in the pathway being regulated; the inducer binds to the _____, thus rendering it _____.
substrate ... repressor ... inactive
You have inserted the gene for human growth factor into the E. coli lactose operon, replacing the structural genes with the gene for human growth factor. What substance must you add to your culture of bacteria to cause them to produce human growth factor for you?
allolactose
Both repressible and inducible operons control gene expression at the level of _____.
transcription
Gene expression in bacteria is regulated primarily by _____.
controlling the transcription of genes into mRNA
The control of gene expression is more complex in multicellular eukaryotes than in prokaryotes because _____.
in a multicellular eukaryote, different cells are specialized for different functions
In some cases DNA methylation and histone deacetylation combine to _____.
silence certain genes
In eukaryotes, DNA packing seems to affect gene expression primarily by
controlling access to DNA
In a eukaryote, activating transcription factors may stimulate gene expression by binding to a DNA site called a(n) _____.
enhancer
What is the evolutionary significance of alternative RNA splicing?
It expands the number of proteins that can be coded for by one gene, increasing an organism's ability to produce novel proteins.
What is the role of proteasomes?
They are giant protein complexes that recognize ubiquitin and degrade the tagged proteins.
What determines how long a particular mRNA molecule will persist in a eukaryotic cell?
nucleotide sequences in the poly-A tail
The expression of a gene located in a tightly coiled region of DNA can be promoted by _____.
histone acetylation
Which of the following statements is NOT associated with epigenetic inheritance?(
chemical mutagens
A high rate of gene transcription in eukaryotic cells is usually dependent on _____.
The third and fourth listed responses are correct.
Which of the following best depicts coordinate control of genes in eukaryotes
The second and third listed responses are correct
Although the number of genes in the human genome is surprisingly low compared to less complex organisms, the number of possible products from those genes is greatly amplified by _____.
alternate arrangements of exons from a primary transcript
Which of the following best describes the makeup of the human genome?
Genes for noncoding RNA make up the majority of meaningful genetic information in the human genome.
MicroRNAs and small interfering RNAs both function similarly in "silencing" genes. What are two ways in which they may act?
degrade mRNA and bind to complementary mRNA sequences to prevent translation
Specific cells that appear undifferentiated under the microscope but are already fated to become muscle cells are called _____
myoblasts
MyoD promotes muscle cell development by _____.
turning on the expression of multiple muscle-related genes
Cytoplasmic determinants _____.
are coded for by maternal genes
Cells can influence each other's development by a process known as
induction
Instead of developing a head and a tail, an abnormal Drosophila embryo develops two tails. This is most likely due to _____.
a mutation in a maternal effect gene
Cell differentiation is first observable when _____.
mRNAs for tissue-specific proteins appear in a cell
In the human genome, oncogenes _____.
stimulate cell division
Most human cancers are _____.
caused by the accumulation of somatic mutations
What two genes are often mutated in colon cancer
ras and p53
Why is cancer more prevalent in older people?
Cancer involves an accumulation of mutations, and older people have had more time to accumulate mutations in their DNA.
In what way can cancer be hereditary?
One or two of several mutations necessary for full cancer development can be inherited, giving a person a predisposition to developing cancer.
Preparing a physical map of the genome involves _____.
cutting the DNA of each chromosome into restriction fragments that overlap, and then determining the original order of the fragments
The whole-genome shotgun approach to genome sequencing is faster and more efficient than earlier sequencing methods because _____.
it avoids the need for a cytogenetic mapping of a genome
What is an advantage of the whole-genome shotgun sequencing approach, compared to the ordered process used by the International Human Genome Consortium?
The whole-genome shotgun approach is much faster.
How do sequence by synthesis techniques differ from previous sequencing methodologies
simultaneous sequencing of many small fragments of DNA, thereby reducing the amount a time required to sequence a genome
For cloning DNA fragments of 100,000 base pairs, one would use ____
bacterial artificial chromosomes
What is a limitation or disadvantage of the whole-genome shotgun (WGS) approach to sequencing?
WGS has difficulty with repeated sequences because there is no corresponding physical map.
Once an organism's genome sequence has been determined, how do scientists generally start identifying all the genes within the genome?
Analyze the sequence using software that scans the sequence for telltale sequence elements such as promoters, transcription start and stop sites, and so on.
What tool or resource is useful for identifying previously unknown protein-coding genes in a genomic DNA sequence?
software that searches for translational start and stop signals
An example of a systems biology experiment might be _____.
determining how insulin resistance affects transcription of thousands of other genes in the genome
Studies that determine gene annotation _____.
identify which genes are protein-coding within a genome
Which of the following best describes the findings of the ENCODE pilot study that thoroughly studied the makeup of a 1% region of the human genome
Over 90% of the region was transcribed into different types of RNA
How can the varying fitness of double-mutant yeast cells provide insights into interactions between gene products
The first, second, and third listed responses are correct.
Why might the number of genes in the genome underestimate the number of different proteins that an organism makes?
Many genes undergo alternative splicing, so that different proteins with different exon combinations are produced from the same gene.
What factor accounts most for the difference in genome size between vertebrates and prokaryotes?
Vertebrates have more noncoding DNA sequences
There is about 1,000 times as much DNA in a human cell as in an E. coli cell, but only about 5 times as many genes. What accounts for this discrepancy?
A human cell has much more noncoding DNA.
Satellite DNA in eukaryotes consists of _____.
simple sequence repeats that have a different base composition than the rest of the genomic DNA
Alu elements _____.
are derived from or related to transposable elements
Segments of eukaryotic DNA that can move from one site to another in the genome by means of an RNA intermediate are called _____.
retrotransposons
Multigene families arise as a result of _____.
errors during DNA replication and recombination
Chromosomal rearrangements may be important in evolution because _____.
chromosome rearrangements lead to gene duplication, thus generating a "spare" copy of the gene that is free to evolve and acquire a new function
The molecular data indicate that the globin gene family _____.
evolved from a common globin gene ancestor that gave rise to both alpha- and beta-globin genes, as well as myoglobin and plant leghemoglobin
A rapid way for natural evolution to alter a protein-coding gene so it encodes a protein with a different structure and function is _____.
exon duplication and exon shuffling
Why might active transposons be rare in natural populations
Individuals with active transposons are usually eliminated by natural selection, because transposition events usually produce harmful mutations.
The highly conserved sequence element present within homeotic genes is called the _____.
homeobox
The similarity of the homeobox in many different kinds of organisms is evidence _____.
of the common ancestry of different life-forms
What can be learned from comparing the genomes of distantly related species, such as yeast and humans, or plants and fruit flies?
Conserved genes provide insight into their evolutionary relationships
What is a valid rationale for sequencing the chimpanzee genome
to determine what genetic changes determine uniquely human features such as large brains and language ability
Detailed comparison of the human and chimpanzee genomes has revealed that _____.
most differences are in the form of chromosomal rearrangements
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 _____.
Aristotle
At the time Darwin voyaged on the 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 _____.
Cuvier
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.
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 overreproduce.
The breeding of plants and animals for particular traits by humans is called
artificial selection
The smallest unit that can evolve is a(n) _____.
population
According to the theory of evolution, anatomical and molecular homologies should _____.
produce similar patterns of evolutionary relatedness
How did some strains of Staphylococcus aureus become resistant to antibiotic drugs
Some members of the bacteria population must have had a genetic variation that made them resistant to antibiotics.
An important challenge to traditional (pre-1860) ideas about species was the observation that seemingly dissimilar organisms such as hummingbirds, humans, and whales have similar skeletal structures. This most directly suggested to biologists that _____.
dissimilar organisms might have evolved from a distant, common ancestor
Animals that possess homologous structures probably _____.
evolved from the same ancestor
On an evolutionary tree _____.
homologous characteristics form a nested pattern
Which of the following is an example of convergent evolution?
Dolphins and sharks have a similar fusiform (streamlined) body shape.
Vestigial organs are _____.
remnants of structures that were useful to an organism's ancestors
All known organisms transcribe genetic information to protein molecules via the same genetic code. This finding strongly supports the hypothesis that _____
all organisms are descended from a single common ancestor
Evidence from molecular biology supports the theory of evolution by demonstrating that _____.
closely related organisms have more similar DNA and proteins
What did Darwin observe about species on islands?
it is a broad model that is supported by many observations and much experimental evidence
In the context of populations, how do we define evolution?
:
Evolution is a change in a population's allele frequencies over generations
Which example below correctly describes average heterozygosity?
Average heterozygosity refers to the average percentage of loci that are heterozygous in a population.
The human genome consists of approximately 3 billion base pairs. If humans typically differ from one another by about 3 million base pairs, what is the nucleotide variability of Homo sapiens
0.1%
Which example below would most likely exhibit a cline?
Rabbits that live in colder regions tend to have smaller ears than rabbits of the same species that live in warmer regions
Which of the following can form entirely new alleles?
mutation
Sexual recombination includes the shuffling of chromosomes in _____ and fertilization.
meiosis
Which type of mutation plays the most important role in increasing the number of genes in the gene pool?
duplication
In the Hardy-Weinberg equation, p2 represents _____.
the expected frequency of homozygous dominant individuals in the population
In the equation for Hardy-Weinberg equilibrium, 1 represents _____.
the sum of the frequencies of the genotypes for a particular gene locus
Assume a population in Hardy-Weinberg equilibrium for a character trait with these genotypic frequencies: AA = 0.25, Aa = 0.50, and aa = 0.25. If you remove all the homozygous dominants and allow the remaining population to reproduce (again under Hardy-Weinberg conditions), what will be the frequency of homozygous dominants in the next generation?
0.11
Which of the following sets of conditions is required for Hardy-Weinberg equilibrium?
random mating, no natural selection, and a large population
_____ and _____ generate variation, whereas _____ results in an adaptation to the environment.
Mutation ... sexual recombination ... natural selection
An earthquake hits a small island. All but a small group of closely related lizards are eliminated, and the survivors spread out over the island. This is an instance of _____.
bottleneck effect
Which of the following scenarios would most likely result in the microevolution of a population of humans
A colony of humans on the moon is isolated from Earth.
Which of the following most accurately measures an organism's fitness
how many fertile offspring it produces
Antibiotic resistance in bacteria is an example of which of the following?
directional selection
Stabilizing selection _____.
favors intermediate variants in a population
Tay-Sachs disease, which is lethal, results from having the homozygous recessive condition of the responsible gene. Which of the following statements is true?
Heterozygous individuals will survive and may pass the recessive allele on to their offspring.
Which of the following would seem to be an example of neutral variation? ( Concept 23.4)
human fingerprints
What is the importance of neutral variation in evolution?
Neutral variation increases genetic variation, allowing a population to carry more alleles that may help it respond to environmental change.
Selection that acts over evolutionary time to preserve traits that increase an individual's ability to mate is known as _____
sexual selection
How does natural selection fashion organisms?
Chance and the environment interact with natural selection, so that the best available traits are selected for
When gene flow between two populations ceases, the potential for _____ exists.
speciation
Which of the following conditions is necessary for speciation to occur
reproductive isolation
At which point in the adaptation of a population is it clear that speciation has occurred
Gene pool changes establish reproductive barriers between two populations.
Prezygotic barriers _____.
prevent fertilization of gametes from members of closely related species
Which of the following reproductive barriers actually prevents individuals of closely related species from copulating successfully?
mechanical isolation
Two species of water lilies in the same pond do not interbreed because one blooms at night and the other during the day. The reproductive barrier between them is an example of _____.
temporal isolation
Which of the following is an example of a postzygotic reproductive barrier?
Two fruit flies of different species produce sterile offspring.
The phylogenetic species concept emphasizes _____.
common ancestry
In practice, how do scientists distinguish most species
by using the morphological species concept
Which species concept defines a species as a set of organisms with a unique genetic history
phylogenetic species concept
Sometimes two phenotypically different populations interbreed to a limited extent, so that it is difficult to determine whether they are clearly separate species. This is not a concern to scientists because this _____.
may indicate that the formation of a new species is in progress
Which of the following organisms is most likely to be subject to allopatric speciation?
pine trees in Alaska and pine trees on the island of Madagascar
According to the experiment of Diane Dodd, can adaptive divergence of allopatric fruit fly populations lead to reproductive isolation?
No. After several generations, the formation of a reproductive barrier (behavioral isolation) was evident, but not absolute.
Which of the following evolutionary mechanisms does NOT contribute to the process of allopatric speciation?
gene flow
In which of the following groups has sympatric speciation been most important
plants
A new species can arise in a single generation _____.
allopatric speciation
In the case of the Lake Victoria cichlids, sympatric speciation has been shown to be driven by _____.
sexual selection
In the Lake Victoria cichlids, what appears to be contributing to fusion of different species
Females have a difficult time visually selecting males of the same species in the murky, polluted water
According to the punctuated equilibrium model of evolution, _____.
the tempo of evolution consists of abrupt episodes of speciation among long periods of equilibrium
What is the first thing that must happen in order for speciation to occur?
Gene flow between populations must be interrupted.
How many genes must change in order to form a new species?
There is no set number of genes or loci that produces a new species. Genetic and environmental factors interact.