Chapters 4, 5, 18

Question 1

Recombination map

Answer 1

A chromosome map in which the positions of loci shown are based on recombinant frequencies.

Question 2

Linked genes

Answer 2

The situation in which two genes are on the same chromosome as deduced by recombinant frequencies less than 50 percent.

Question 3

Thomas Hunt Morgan’s experiment with ____ led to linkage hypothesis

Answer 3

Fruit flies

Question 4

When two genes are close together on the same chromosome pair (that is, when they are linked), they do not ______

Answer 4

Assort independently

Question 5

a recombinant frequency of _____ percent is a diagnostic for linkage.

Answer 5

Less than 50

Question 6

During meiosis, when duplicated homologous chromosomes pair with each other, a cross-shaped structure called a ____ often forms between two nonsister chromatids.

Answer 6

Chiasma

Question 7

For linked genes, recombinants are produced by crossovers between _____ chromatids during meiosis.

Answer 7

nonsister

Question 8

cis formation

Answer 8

In a heterozygote having two mutant sites within a gene or within a gene cluster, the arrangement A1A2/a1a2.

Question 9

trans formation

Answer 9

In a heterozygote with two mutant sites within a gene or gene cluster, the arrangement a1 +/+ a2.

Question 10

A ____ is the breakage of two DNA molecules at the same position and their rejoining in two reciprocal recombinant combinations.

Answer 10

crossover

Question 11

To study double crossovers, we need ___ linked genes

Answer 11

3

Question 12

Crossovers between sister chromatids are ____

Answer 12

Rare

Question 13

A chromosome map; an abstract map of chromosomal loci that is based on recombinant frequencies.

Answer 13

Linkage map

Question 14

A distance on the chromosome map corresponding to 1 percent recombinant frequency

Answer 14

genetic map unit (aka centimorgan)

Question 15

Three point testcross

Answer 15

A testcross in which one parent has three heterozygous gene pairs.

Question 16

larger RF value indicates 2 loci are

Answer 16

further apart

Question 17

Typically, for linked genes, we have the eight genotypes at the following frequencies:

Answer 17

two at high frequency
two at intermediate frequency
two at a different intermediate frequency
two rare

Question 18

Interference

Answer 18

A measure of the independence of crossovers from each other, calculated by subtracting the coefficient of coincidence from 1.

Question 19

a crossover does ____ the probability of a crossover in an adjacent region.

Answer 19

reduce

Question 20

coefficient of coincidence (c.o.c.)

Answer 20

The ratio of the observed number of double recombinants to the expected number.

Question 21

Interference = (give equation)

Answer 21

1 - (observed double recombinant frequency / expected double recombinant frequency)

Question 22

when there are not any observed double recombinants, what is c.o.c.?

Answer 22

zero

Question 23

Longer regions have ___ crossovers and thus _____ recombinant frequencies

Answer 23

more; higher

Question 24

Molecular marker

Answer 24

a locus of heterozygosity due to changes in DNA sequences (e.g. nucleotide substitution, insertion , deletion etc.)

Question 25

2 types of molecular markers

Answer 25

Single nucleotide polymorphisms (SNPs) Simple sequence length polymorphism (SSLPs)

Question 26

Advantage of using molecular markers: (name 2)

Answer 26

Abundant Mostly neutral (directly measure genotype)

Question 27

haplosufficient

Answer 27

a single normal allele provides enough function, so A+A− individuals are healthy

Question 28

Haploinsufficient

Answer 28

one wild type allele can not produce enough product

Question 29

Dominant negative

Answer 29

Mutant allele acts as a spoiler

Question 30

Incomplete Dominance

Answer 30

The heterozygote does not resemble either parents, it has an intermediate phenotype (i.e. pink flowers with red and white parentals)

Question 31

Codominance

Answer 31

Both alleles in a heterozygote express their phenotypes (i.e. blood type AB)

Question 32

hypostatic gene

Answer 32

one whose phenotype is altered by the expression of an allele at a separate locus, in an epistasis event.

Question 33

one gene–one enzyme hypothesis

Answer 33

the idea that genes act through the production of enzymes, with each gene responsible for producing a single enzyme that in turn affects a single step in a metabolic pathway.

Question 34

epistasis

Answer 34

the interaction of genes that are not alleles, in particular the suppression of the effect of one such gene by another.

Question 35

auxotroph

Answer 35

a mutant organism (especially a bacterium or fungus) that requires a particular additional nutrient which the normal strain does not.

Question 36

In dominant epistasis, only a single copy of an allele is required to inhibit the expression of an allele at a different locus, which gives rise to the ____ ratio of the F2 generation.

Answer 36

12:3:1

Question 37

leaky mutation

Answer 37

some function

Question 38

null mutation

Answer 38

all function lost

Question 39

An individual will lack essential function and die if there are null mutations in how many duplicate systems?

Answer 39

Both

Question 40

3 colors of lab retrievers ratio

Answer 40

9:3:4

Question 41

Yellow labs are the result of

Answer 41

recessive epistasis

Question 42

Complementation

Answer 42

a relationship between two different strains of an organism which both have homozygous recessive mutations that produce the same phenotype

Question 43

pleiotropy

Answer 43

the production by a single gene of two or more apparently unrelated effects.

Question 44

haplotype

Answer 44

a unique combination of variants that reside near each other on a chromosome

Question 45

Which organism can benefit from inbreeding?

Answer 45

Plants

Question 46

If the association between the alleles at two loci is random, then the two loci are said to be at

Answer 46

linkage equilibrium.

Question 47

Noncoding SNPs (ncSNPs) are found in

Answer 47

introns

Question 48

mutation rate

Answer 48

the probability that a copy of an allele changes to some other allelic form in one generation.

Question 49

Inbreeding can lead to a reduction in vigor and reproductive success called

Answer 49

inbreeding depression

Question 50

Other than mutation, the only other means for new variation to enter a population is through

Answer 50

migration / gene flow

Question 51

microsatellite

Answer 51

a tract of repetitive DNA in which certain DNA motifs are repeated, typically 5–50 times

Question 52

flanking sequence

Answer 52

A DNA sequence located adjacent to a gene, either upstream from its 5'-end or downstream from its 3'-end.