Chapter 21 Genomes and their Evolution
The human genome is thought to contain about how many genes? ()
20,000-25,000
Given that about 25% of the mammalian genome is associated with genes,including introns and regulatory sequence, what would be the approximate average length of DNA per gene, if the genome contained 20,000 genes?
40,000 base pairs
Although containing the same number of genes as the nematode genome, the human genome is thought to bear greater phenotypic diversity by means of_____. ()
All of the listed responses are correct.
NCBI provides _____.
All of the listed responses are correct.
The eukaryotic genome is much less tidy and compact than the genomes of prokaryotes. Eukaryotes, but not prokaryotes, have _____.
All of the listed responses are correct.
The number of genes in an organism's genome is not a perfect indication of the organism's complexity because _____. ()
All of the listed responses are correct.
Among the organisms listed below, which has the largest genome? ()
Amoeba dubia
For cloning DNA fragments of 100,000 base pairs, one would use _____.
bacterial artificial chromosomes
The molecular data indicate that the globin gene family _____.
both alpha- and beta-globin genes, as well as myoglobin and plant leghemoglobin
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
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.
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 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.
A gene family has been identified that has undergone extensive duplication in humans, but is present in only one or a few copies in other primates or other mammals. What experimental approaches could be used to determine the function of this gene and its significance in human evolution? ()
Create knockout mice to determine their phenotype.
Why might a dog genome sequencing project prove particularly informative,compared to other mammalian genomes? ()
Genetic variation between breeds may be linked to phenotypic variation.
A rapid way for natural evolution to alter a protein-coding gene so it encodes a protein with a different structure and function is _____.
How do transposable elements promote functional genetic diversity in a population? ()
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.
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.
Who discovered "jumping genes" (transposons)?
McClintock
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.
Which of the following best describes the experimental evidence that the FOXP2 gene is vital to the normal development of vocalization in vertebrates and yet has evolved among different vertebrate lineages? ()
Replacing the FOX2P gene in mice with a humanized version of the gene had no negative effects on the mice but did lead to the development of brain cells in neural circuits that are associated with speech development in humans.
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.
What is an advantage of the whole-genome shotgun sequencing approach,compared to the ordered process used by the International Human GenomeConsortium? ()
The whole-genome shotgun approach is much faster.
Alu elements _____.
They appear to be derived from a retrotransposon.
What factor accounts most for the difference in genome size between vertebrates and prokaryotes? ()
Vertebrates have more noncoding DNA sequences.
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.
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.
An example of a systems biology experiment might be _____. ()
determining how insulin resistance affects transcription of thousand other genes.
Multigene families arise as a result of _____.
errors during DNA replication and recombination
The highly conserved sequence element present within homeotic genes is called the _____.
homeobox
Studies that determine gene annotation _____. ()
identify which genes are protein-coding within a genome
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
Detailed comparison of the human and chimpanzee genomes has revealed that _____. ()
most differences are in the form of chromosomal rearrangements
The advantage of copy-number variants (CNVs) over SNPs in human genomic studies is that CNVs _____. ()
occupy much longer stretches of DNA than SNPs, and are likely to have greater phenotypic consequences
The similarity of the homeobox in many different kinds of organisms is evidence _____. ()
of the common ancestry of different life-forms
Segments of eukaryotic DNA that can move from one site to another in the genome by means of an RNA intermediate are called _____.
retrotransposons
Satellite DNA in eukaryotes consists of _____.
simple sequence repeats that have a different base composition than the rest of the genomic DNA
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
How do sequence by synthesis techniques differ from previous sequencing methodologies? ()
the use of computer programs to arrange the correct order of DNA fragments that are first sequenced
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
A group of scientists is attempting to sequence the Neanderthal genome with DNA extracted from Neanderthal bones. Information from this project might reveal _____.
what genetic differences may be responsible for the superior abilities of modern humans to communicate and make more sophisticated tools