Ch. 6 Connect

Question 1

Morgan proposed that the likelihood of crossing Ober depends on the ___ between two genes.

Answer 1

Distance

Question 2

If a diploid fungus zygote undergoes meiosis followed by mitosis, the result is a(n) ___.

Answer 2

Octad

Question 3

Distance on a chromosome is generally measured in…

Answer 3

Mapunits and centiMorgans

Question 4

Order the steps in applying the chi square test to distinguish between linkage and independent assortment.

Answer 4

• propose a hypothesis
• based on the hypothesis, calculate the expected value of each of the four phenotypes
• apply the chi square formula, using the data for observed and expected values
• interpret the calculated chi square value

Question 5

The purpose of ___ mapping is to determine the linear order and the distance between genes on the same ___.

Answer 5

Genetic; chromosome

Question 6

A diploid cell has a pair of homologous chromosomes. One chromosome has the alleles FGH and the other chromosome has the alleles fgh. The cell undergoes meiosis. Which alleles are found in the nonrecombinant haploid cells?

Answer 6

fgh and FGH

Question 7

A crossover is unlikely to occur in the region between two genes when they are ..

Answer 7

Close together

Question 8

The goal of a ___ is to find out if recombination has occurred during meiosis in the ___ parent in the cross between a heterozygous individual and a homologous recessive individual.

Answer 8

Testcross; heterozygous

Question 9

Because bacterial cells contain one large circular chromosome, all genes within that chromosome are ___.

Answer 9

Syntenic

Question 10

Crossing over occurs during ___ of meiosis I.

Answer 10

Prophase

Question 11

When considering two genes on a fly chromosome, if a fly cross yields 63 recombinant offspring out of 656 total offspring, what is the distance between the two genes in question?

Answer 11

9.6 map units

Question 12

What is the name of the process that involves crossing over during meiosis, generating a new combination of alleles?

Answer 12

Genetic recombination

Question 13

Place in order from first to last these steps for using a three-factor cross to map genes.

Answer 13

• cross two true-breeding strains that differ with regard to three alleles
• perform a testcross by mating F1 female heterozygotes to male flies that are homozygous recessive for all three alleles
• collect data for the F2 generation
• calculate the map distance between pairs of genes
• construct the map

Question 14

A ___ ___ is a diagram that describes the order of genes along a chromosome.

Answer 14

Genetic map

Question 15

Crossing over during ___ occurs much less frequently than crossing over during ___.

Answer 15

Mitosis; meiosis

Question 16

To conduct a chi square analysis to discriminate between linkage and independent assortment in a cross, a scientist needs:

Answer 16

• a hypothesis
• the expected number of recombinant offspring
• the expected number of nonrecombinant offspring

Question 17

When two genes are linked, offspring tend to inherit the ___ pattern of alleles more often than the ___ pattern of alleles.

Answer 17

Non-recombinant; recombinant

Question 18

In a chi square analysis, the ___ ___ assumes there is no difference between observed and expected values.

Answer 18

Null hypothesis

Question 19

Based on mendels law of independent assortment, what phenotypic ratio should the offspring of a two-factor cross between two individuals heterozygous for two genes show?

Answer 19

9:3:3:1

Question 20

Compared to two-factor testcrosses, three-factor testcrosses can provide additional information about..

Answer 20

• gene order

- map distance

Question 21

The site where a gene is found on a particular chromosome is called its ___.

Answer 21

Locus

Question 22

Offspring that display the same combination of alleles that were found in the chromosomes of their parents are called ___ offspring.

Answer 22

Nonrecombinant

Question 23

How many total linkage groups does a cell from a human male contain?

Answer 23

25

22 autosomal linkages groups, and X, a Y, and a mitochondrial genome linkage group

Question 24

Within what structure does crossing over occur?

Answer 24

Bivalent

Question 25

The phenomenon in which genes that are close together on the same chromosome tend to be transmitted as a unit is ___ ___.

Answer 25

Genetic linkage

Question 26

The linear arrangement of genes on a chromosome is depicted on a ___ ___ map.

Answer 26

Genetic linkage

Question 27

The benefits of genetic mapping

Answer 27

- allows geneticists to understand the overall complexity and genetic organization of a particular species - from an evolutionary point of view - diagnose and perhaps someday treat inherited human diseases - gaining increasing importance in agriculture

Question 28

In developing a hypothesis to explain Morgan's fly data, we assume that..

Answer 28

- the alleles in question follow the law of segregation | - the four phenotypes produced by his crosses are equally viable

Question 29

The ___ ___ allows us to calculate the likelihood of a double crossover if we know the individual likelihood of each single crossover.

Answer 29

Product rule

Question 30

What explanation did Bateson and Punnett offer for their results in which the observed numbers from a two-factor cross did not conform to a 9:3:3:1 ratio?

Answer 30

The transmission of the two characters from the parental generation to the F2 generation was coupled and not assorted independently.

Question 31

In yeast crosses involving two genes of interest, double crossovers can yield a..

Answer 31

- tetratype - parental ditype - nonparental ditype

Question 32

In a three-factor cross, the goal of the first step is to obtain F1 individuals that are ___ for all three genes.

Answer 32

Heterozygous

Question 33

In a three-factor cross involving linked genes, the ___ phenotype occurs more frequently.

Answer 33

Nonrecombinant

Question 34

Fungi can reproduce..

Answer 34

Sexually and asexually

Question 35

The transmission pattern of two or more characters is affected by..

Answer 35

Their linkage on a chromosome

Question 36

A yeast tetrad containing four spores with the nonrecombinant arrangement of alleles is said to exhibit the ___ ___.

Answer 36

Parental ditype

Question 37

In conducting a chi square analysis of a two factor cross, if the chi square value is ___, we cannot reject the null hypothesis, and we infer that the genes assort ___.

Answer 37

Low; independently

Question 38

In a testcross, if the genes in question are linked, how does the number of recombinant offspring relate to the number of nonrecombinant offspring?

Answer 38

There are fewer recombinant offspring than nonrecombinant offspring