Ch. 7 Linkage, Recombination, & Eukaryotic Gene Mapping

Question 1

linked genes

Answer 1

genes located close together on the same chromosome

Question 2

linkage group

Answer 2

a group of linked genes

Question 3

nonrecombinant (parental) gamete

Answer 3

gamete that contains only the original combinations of alleles present in the parents

Question 4

nonrecombinant (parental) progeny

Answer 4

progeny that possess only the original combinations of traits possessed by the parents

Question 5

recombinant gamete

Answer 5

gamete that possesses new combinations of alleles

Question 6

recombinant progeny

Answer 6

progeny formed from recombinant gametes that possess new combinations of traits

Question 7

recombination frequency

Answer 7

proportion of recombinant progeny produced in a cross

Question 8

coupling (cis) configuration

Answer 8

arrangement of linked genes in which the wild-type alleles of two or more genes are on one chromosome and their mutant alleles are on the homologous chromosome

Question 9

repulsion (trans) configuration

Answer 9

arrangement of two linked genes in which each of a homologous pair of chromosomes contains one wild-type (dominant) allele and one mutant (recessive) allele

Question 10

genetic map

Answer 10

map of the relative distances between genetic loci, markers, or other chromosome regions determined by rates of recombination; measured in recombination frequencies or map units

Question 11

physical map

Answer 11

map of physical distances between loci, genetic markers, or other chromosome segments; measured in base pairs

Question 12

map unit (m.u)

Answer 12

unit of measure for distances on a genetic map; also called a centiMorgan. 1 map unit equals a recombination frequency of 1%

Question 13

centiMorgan (cM)

Answer 13

a map unit

Question 14

two-point testcross

Answer 14

cross between an individual heterozygous at two loci and an individual homozygous for recessive alleles at those loci

Question 15

three-point testcross

Answer 15

cross between an individual heterozygous at three loci and an individual homozygous for recessive alleles at those loci

Question 16

interference

Answer 16

degree to which one crossover interferes with additional crossovers

Question 17

coefficient of coincidence

Answer 17

ratio of observed double crossovers to expected double crossovers

Question 18

mapping function

Answer 18

mathematical function that relates recombination frequencies to actual physical distances between genes

Question 19

lod (logarithm of odds) score

Answer 19

logarithm of the ratio of the probability of obtaining a set of observations, assuming a specified degree of linkage, to the probability of obtaining the same set of observations with independent assortment; used to assess the likelihood of linkage between genes from pedigree data

Question 20

genetic marker

Answer 20

any gene or DNA sequence used to identify a location on a genetic or physical map

Question 21

linkage analysis

Answer 21

gene mapping based on the detection of physical linkage between genes, as measured by the rate of recombination in the progeny of a cross

Question 22

genome-wide association study

Answer 22

a study that looks for nonrandom associations between the presence of a trait and alleles at many different loci scattered across a genome - that is, for associations between traits and particular suites of alleles in a population

Question 23

haplotype

Answer 23

a specific set of linked genetic variants or alleles on a single chromosome or on part of a chromosome

Question 24

linkage disequilibrium

Answer 24

nonrandom association between genetic variants within a haplotype

Question 25

single-nucleotide polymorphism (SNP)

Answer 25

a single-base-pair difference in DNA sequence between individual members of a species

Question 26

somatic-cell hybridization

Answer 26

fusion of somatic cells of different types

Question 27

cell line

Answer 27

genetically identical cells that divide indefinitely and can be cultured in the laboratory

Question 28

heterokaryon

Answer 28

cell possessing two nuclei derived from different cells through cell fusion

Question 29

deletion mapping

Answer 29

technique for determining the chromosomal location of a gene by studying the association of its phenotype or product with particular chromosome deletions