Chapter 6 Genetic Techniques

Question 1

PCR

Answer 1

• Polymerase chain reaction
• highly versatile method
• amplify a specific genomic DNA sequence, a cDNA or a sequence at the junction between a DNA and transposon and flanking chromosomal sequences

Question 2

Southern Blotting

Answer 2

Technique used to detect DNA fragments of a specific sequence

Question 3

alleles

Answer 3

One of two or more alternative forms of a gene.

Diploid cells contain two alleles of each gene, located at the corresponding site (locus) on homologous chromosomes.

Question 4

clone

Answer 4

(1) A population of genetically identical cells, viruses, or
organisms descended from a common ancestor.

(2) Multiple identical copies of a gene or DNA fragment generated and maintained
via DNA cloning.

Question 5

cDNAs

Answer 5

cDNA = complementary DNA

DNA molecule copied from an mRNA molecule by reverse ranscriptase and therefore lacking the introns present in the DNA of the genome

Question 6

DNA cloning

Answer 6

Recombinant DNA technique in which specific cDNAs or fragments of genomic DNA are inserted into a cloning
vector, which then is incorporated into cultured host cells and maintained during growth of the host cells; also called gene cloning. (Figure 6-14)

Question 7

DNA library

Answer 7

Collection of cloned DNA molecules consisting of fragments of the entire genome (genomic library) or of DNA copies of all the mRNAs produced by a cell type (cDNA library) inserted into a suitable cloning vector.

Question 8

DNA microarray

Answer 8

An ordered set of thousands of different nucleotide
sequences arrayed on a microscope slide or other solid surface; can be used to determine patterns of gene expression in different cell types or in a particular cell type at different developmental stages or under different conditions. (Figures 5-29 and 5-30)

Question 9

functional complementation

Answer 9

Procedure for screening a DNA library to identify the wild-type gene that restores the function of a defective gene in a particular mutant. (Figure 6-16)

Question 10

gene knockout

Answer 10

Selective inactivation of a specific gene by replacing
it with a nonfunctional (disrupted) allele in an otherwise
normal organism.

Question 11

genotype

Answer 11

Entire genetic constitution of an individual cell or organism, usually with emphasis on the particular alleles at one or more specific loci.

Question 12

heterozygous

Answer 12

Referring to a diploid cell or organism having two different alleles of a particular gene.

Question 13

homozygous

Answer 13

Referring to a diploid cell or organism having two identical alleles of a particular gene.

Question 14

hybridization

Answer 14

Association of two complementary nucleic acid strands to form double-stranded molecules, which can contain two DNA strands, two RNA strands, or one DNA and one RNA strand. Used experimentally in various ways to detect
specific DNA or RNA sequences.

Question 15

in situ hybridization

Answer 15

Any technique for detecting specific DNA or RNA sequences in cells and tissues by treating samples with
single-stranded RNA or DNA probes that hybridize to the sequence of interest. (Figure 6-25)

Question 16

linkage

Answer 16

In genetics, the tendency of two different loci on the
same chromosome to be inherited together. The closer two loci are, the lower the frequency of recombination between them and the greater their linkage.

Question 17

mutagen

Answer 17

A chemical or physical agent that induces mutations.

Question 18

mutation

Answer 18

In genetics, a permanent, heritable change in the nucleotide sequence of a chromosome, usually in a single gene; commonly causes an alteration in the function of the gene product.

Question 19

Northern blotting

Answer 19

Technique for detecting specific RNAs separated by electrophoresis by hybridization to a labeled DNA probe.

Question 20

phenotype

Answer 20

The detectable physical and physiological characteristics
of a cell or organism determined by its genotype; also, the
specific trait associated with a particular allele

Question 21

plasmids

Answer 21

Small, circular extrachromosomal DNA molecule capable
of autonomous replication in a cell; commonly used as a
vector in DNA cloning.

Question 22

point mutation

Answer 22

Change of a single nucleotide in DNA, especially in a region coding for protein; can result in formation of a codon specifying a different amino acid or a stop codon. Addition or deletion of a single nucleotide will cause a shift in the reading frame

Question 23

recombinant DNA

Answer 23

Any DNA molecule formed in vitro by joining DNA fragments from different sources

Question 24

restriction enzymes

Answer 24

Any enzyme that recognizes and cleaves a specific short sequence, the restriction site, in double-stranded DNA
molecules; used extensively to produce recombinant DNA in vitro;
aka. restriction endonuclease
(Figure 6-11; Table 6-1)

Question 25

RNAi

Answer 25

• RNA interference
• Functional inactivation of a specific gene by a corresponding double-stranded RNA that induces
  either inhibition of translation or degradation of the complementary single-stranded mRNA encoded by the gene but not that of mRNAs with a different sequence. (Figures 6-42)

Question 26

transfection

Answer 26

Experimental introduction of foreign DNA into cells in culture, usually followed by expression of genes in the
introduced DNA. (Figure 6-29)

Question 27

transgenes

Answer 27

A cloned gene that is introduced and stably incorporated into a plant or animal and is passed on to successive
generations.

Question 28

vector

Answer 28

In cell biology, an autonomously replicating genetic
element used to carry a cDNA or fragment of genomic DNA into a host cell for the purpose of gene cloning. Commonly used vectors are bacterial plasmids and modified bacteriophage genomes. See also expression vector and shuttle vector. (Figure 6-13)

Question 29

wild type

Answer 29

Normal, nonmutant form of a gene, protein, cell, or
organism.