BSC 114 Chapter 21 Mastering Biology

Segments of eukaryotic DNA that can move from one site to another in the genome by means of an RNA intermediate are called __________.

retrotransposons

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

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

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

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.

How do transposable elements promote genetic diversity in a population?

A transposable element may cause genetic diversity by any of the above methods

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

The human genome is thought to contain about how many genes?

20,000-25,000

Recall that the human genome contains roughly 3 billion base pairs per haploid genome, and 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 human gene, if the genome contained 20,000 genes?

40,000 base pairs

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 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 eukaryotic genomes 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 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 FOXP2 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.

What factor accounts most for the difference in genome size between vertebrates and prokaryotes?

Vertebrates have more noncoding DNA sequences.

Alu elements __________.

are derived from or related to transposable elements

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

An example of a systems biology experiment might be __________.

determining how insulin resistance affects transcription of thousands of other genes in the genome

Multigene families arise as a result of __________.

errors during DNA replication and recombination

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

Evolution can rapidly alter a protein-coding gene so it encodes a protein with a different structure and function through __________.

exon duplication and exon shuffling

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

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

Scientists have succeeded in sequencing 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