Ch. 6 Connect Flashcards
Morgan proposed that the likelihood of crossing Ober depends on the ___ between two genes.
Distance
If a diploid fungus zygote undergoes meiosis followed by mitosis, the result is a(n) ___.
Octad
Distance on a chromosome is generally measured in…
Mapunits and centiMorgans
Order the steps in applying the chi square test to distinguish between linkage and independent assortment.
- 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
The purpose of ___ mapping is to determine the linear order and the distance between genes on the same ___.
Genetic; chromosome
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?
fgh and FGH
A crossover is unlikely to occur in the region between two genes when they are ..
Close together
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.
Testcross; heterozygous
Because bacterial cells contain one large circular chromosome, all genes within that chromosome are ___.
Syntenic
Crossing over occurs during ___ of meiosis I.
Prophase
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?
9.6 map units
What is the name of the process that involves crossing over during meiosis, generating a new combination of alleles?
Genetic recombination
Place in order from first to last these steps for using a three-factor cross to map genes.
- 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
A ___ ___ is a diagram that describes the order of genes along a chromosome.
Genetic map
Crossing over during ___ occurs much less frequently than crossing over during ___.
Mitosis; meiosis
To conduct a chi square analysis to discriminate between linkage and independent assortment in a cross, a scientist needs:
- a hypothesis
- the expected number of recombinant offspring
- the expected number of nonrecombinant offspring
When two genes are linked, offspring tend to inherit the ___ pattern of alleles more often than the ___ pattern of alleles.
Non-recombinant; recombinant
In a chi square analysis, the ___ ___ assumes there is no difference between observed and expected values.
Null hypothesis
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?
9:3:3:1
Compared to two-factor testcrosses, three-factor testcrosses can provide additional information about..
- gene order
- map distance
The site where a gene is found on a particular chromosome is called its ___.
Locus
Offspring that display the same combination of alleles that were found in the chromosomes of their parents are called ___ offspring.
Nonrecombinant
How many total linkage groups does a cell from a human male contain?
25
22 autosomal linkages groups, and X, a Y, and a mitochondrial genome linkage group
Within what structure does crossing over occur?
Bivalent
The phenomenon in which genes that are close together on the same chromosome tend to be transmitted as a unit is ___ ___.
Genetic linkage
The linear arrangement of genes on a chromosome is depicted on a ___ ___ map.
Genetic linkage
The benefits of genetic mapping
- 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
In developing a hypothesis to explain Morgan’s fly data, we assume that..
- the alleles in question follow the law of segregation
- the four phenotypes produced by his crosses are equally viable
The ___ ___ allows us to calculate the likelihood of a double crossover if we know the individual likelihood of each single crossover.
Product rule
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?
The transmission of the two characters from the parental generation to the F2 generation was coupled and not assorted independently.
In yeast crosses involving two genes of interest, double crossovers can yield a..
- tetratype
- parental ditype
- nonparental ditype
In a three-factor cross, the goal of the first step is to obtain F1 individuals that are ___ for all three genes.
Heterozygous
In a three-factor cross involving linked genes, the ___ phenotype occurs more frequently.
Nonrecombinant
Fungi can reproduce..
Sexually and asexually
The transmission pattern of two or more characters is affected by..
Their linkage on a chromosome
A yeast tetrad containing four spores with the nonrecombinant arrangement of alleles is said to exhibit the ___ ___.
Parental ditype
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 ___.
Low; independently
In a testcross, if the genes in question are linked, how does the number of recombinant offspring relate to the number of nonrecombinant offspring?
There are fewer recombinant offspring than nonrecombinant offspring
