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Genetics > Chapters 4, 5, 18 > Flashcards

Chapters 4, 5, 18 Flashcards

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1
Q

Recombination map

A

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

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2
Q

Linked genes

A

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

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3
Q

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

A

Fruit flies

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4
Q

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

A

Assort independently

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5
Q

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

A

Less than 50

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6
Q

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

A

Chiasma

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7
Q

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

A

nonsister

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8
Q

cis formation

A

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

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9
Q

trans formation

A

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

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10
Q

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

A

crossover

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11
Q

To study double crossovers, we need ___ linked genes

A

3

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12
Q

Crossovers between sister chromatids are ____

A

Rare

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13
Q

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

A

Linkage map

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14
Q

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

A

genetic map unit (aka centimorgan)

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15
Q

Three point testcross

A

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

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16
Q

larger RF value indicates 2 loci are

A

further apart

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17
Q

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

A

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

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18
Q

Interference

A

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

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19
Q

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

A

reduce

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20
Q

coefficient of coincidence (c.o.c.)

A

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

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21
Q

Interference = (give equation)

A

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

22
Q

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

A

zero

23
Q

Longer regions have ___ crossovers and thus _____ recombinant frequencies

A

more; higher

24
Q

Molecular marker

A

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

25
Q

2 types of molecular markers

A

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

26
Q

Advantage of using molecular markers:
(name 2)

A

Abundant
Mostly neutral (directly measure genotype)

27
Q

haplosufficient

A

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

28
Q

Haploinsufficient

A

one wild type allele can not produce enough product

29
Q

Dominant negative

A

Mutant allele acts as a spoiler

30
Q

Incomplete Dominance

A

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

31
Q

Codominance

A

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

32
Q

hypostatic gene

A

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

33
Q

one gene–one enzyme hypothesis

A

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.

34
Q

epistasis

A

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

35
Q

auxotroph

A

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

36
Q

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.

A

12:3:1

37
Q

leaky mutation

A

some function

38
Q

null mutation

A

all function lost

39
Q

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

A

Both

40
Q

3 colors of lab retrievers ratio

A

9:3:4

41
Q

Yellow labs are the result of

A

recessive epistasis

42
Q

Complementation

A

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

43
Q

pleiotropy

A

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

44
Q

haplotype

A

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

45
Q

Which organism can benefit from inbreeding?

A

Plants

46
Q

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

A

linkage equilibrium.

47
Q

Noncoding SNPs (ncSNPs) are found in

A

introns

48
Q

mutation rate

A

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

49
Q

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

A

inbreeding depression

50
Q

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

A

migration / gene flow

51
Q

microsatellite

A

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

52
Q

flanking sequence

A

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

Genetics (6 decks)

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