Chapter 20

Question 1

nucleic acid hybridization

Answer 1

the base pairing of one strand of a nucleic acid to the complementary sequence on a strand from another nucleic acid molecule

Question 2

genetic engineering

Answer 2

direct manipulation of genes for practical purposes

Question 3

DNA sequencing

Answer 3

determining the complete nucleotide sequence of a gene or DNA segment

Question 4

DNA cloning

Answer 4

the production of multiple copies of a specific DNA segment

Question 5

plasmid

Answer 5

a small, circular, double stranded DNA molecule that carries accessory genes separate from those of a bacterial chromosome; in DNA cloning, plasmids are used as vectors carrying up to 10,000 base pairs of DNA

Question 6

recombinant DNA molecule

Answer 6

a DNA molecule made in vitro with segments from different sources

Question 7

gene cloning

Answer 7

the production of multiple copies of a gene

Question 8

cloning vector

Answer 8

in genetic engineering, a DNA molecule that can carry foreign DNA into a host cell and replicate there. cloning vectors include plasmids and bacterial artificial chromosomes (BACs) which move recombinant DNA from a test tube back into a cell, and viruses that transfer recombinant DNA by infection

Question 9

restriction enzymes

Answer 9

a type of enzyme that recognizes and cuts DNA molecules foreign to a bacterium; the enzyme cuts at specific nucleotide sequences (restriction sites)

Question 10

restriction site

Answer 10

a specific sequence on a DNA strand that is recognized and cut by a restriction enzyme

Question 11

restriction fragments

Answer 11

a DNA segment that results from the cutting of DNA by a restriction enzyme

Question 12

sticky end

Answer 12

a single stranded end of a double stranded restriction fragment

Question 13

gel electrophoresis

Answer 13

a technique for separating nucleic acids or proteins on the basis of their size and electrical charge, both of which affect their rate of movement thru an electric field in a gel made of agarose or another polymer

Question 14

polymerase chain reaction (PCR)

Answer 14

a technique for amplifying DNA in vitro by incubating it with specific primers, a heat resistant DNA polymerase, and nucleotides

Question 15

expression vector

Answer 15

a cloning vector that contains a highly active bacterial promoter just upstream of a restriction site where a eukaryotic gene can be inserted, allowing the gene to be expressed in a bacterial cell; expression vectors are also available that have been genetically engineering for use in specific types of eukaryotic cells

Question 16

electroporation

Answer 16

a technique used to introduce recombinant DNA into cells by applying a brief electrical pulse to a solution containing the cells; creates temporary holes in the cells’ plasma membranes, thru which DNA can enter

Question 17

nucleic acid probe

Answer 17

a labeled single-stranded nucleic acid molecule used to locate a specific nucleotide sequence in a nucleic acid sample; molecules of the probe hydrogen-bond to the complementary sequence wherever it occurs; radioactive, fluorescent, or other labeling of the probe allows its location to be detected

Question 18

in situ hybridization

Answer 18

a technique using nucleic acid hybridization with a labeled probe to detect the location of a specific mRNA in an intact organism

Question 19

reverse transcriptase polymerase chain reaction (RT-PCR)

Answer 19

a technique for determining expression of a particular gene; uses reverse transcriptase and DNA polymerase to synthesize cDNA from all the mRNA in a sample and then subjects the cDNA to PCR amplification using primers specific for the gene of interest

Question 20

complementary DNA (cDNA)

Answer 20

a double stranded DNA molecule made in vitro using mRNA as a template and the enzymes reverse transcriptase and DNA polymerase; a cDNA molecule corresponds to the exons of a gene

Question 21

RNA sequencing (RNA-seq)

Answer 21

a method of analyzing large sets of RNAs that involves making cDNAs and sequencing them

Question 22

DNA microarray assay

Answer 22

a method to detect and measure the expression of thousands of genes at one time; tiny amounts of a large number of single-stranded DNA fragments representing different genes are fixed to a glass slide and tested for hybridization with samples of labeled cDNA

Question 23

in vitro mutagenesis

Answer 23

a technique used to discover the function of a gene by cloning it, introducing specific changes into the cloned gene’s sequence, reinserting the mutated gene into a cell, and studying the phenotype of the mutant

Question 24

gene drive

Answer 24

a process that biases inheritance such that a particular allele is more likely to be inherited than are other alleles, causing the favored allele to spread through the population

Question 25

RNA interference (RNAi)

Answer 25

a mechanism for silencing the expression of specific genes; double stranded RNA molecules that match the sequence of a particular gene are processed into siRNAs that either block translation or trigger the degradation of the gene’s messenger RNA

Question 26

single nucleotide polymorphism (SNP)

Answer 26

a single base pair site in a genome where nucleotide variation is found in at least 1% of the population

Question 27

stem cell

Answer 27

any relatively unspecialized cell that can produce, during a single division, two identical daughter cells or two more specialized daughter cells that can undergo further differentiation, or one cell of each type

Question 28

totipotent

Answer 28

describing a cell that can give rise to all parts of the embryo and adult, as well as extraembryonic membranes in species that have them

Question 29

transgene

Answer 29

a gene that has been transferred naturally or by a genetic engineering technique from one organism to another

Question 30

genetic profile

Answer 30

an individual’s unique set of genetic markers, detected most often today by PCR

Question 31

short tandem repeats (STRs)

Answer 31

simple sequence DNA containing multiple tenderly repeated units of two to five nucleotides; variations in STRs act as genetic markers in STR analysis, used to prepare genetic profiles