Genetics Lab midterm

In fruit flies, bristle shape is found to be incompletely dominant with wild being homozygous (+,+), mild being heterozygous (+,b) and bent bristled flies being homozygous (b,b). For eye color, orange is dominant over wild in a simple Mendelian fashion. Assume that two mild bristled, orange eyed flies (standard F1 cross) are mated, how many of their 560 progeny would you expect to be wild bristled, orange eyed?

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In fruit flies, bristle shape is found to be incompletely dominant with wild being homozygous (+,+), mild being heterozygous (+,b) and bent bristled flies being homozygous (b,b). For mandible size, wild type is heterozygous (+,m), short is homozygous (+,+) and long is homozygous (m,m). Assume that two mild bristled, wild mandible flies (standard F1 cross) are mated, how many of their 560 progeny would you expect to be bent bristled, wild mandible?

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In fruit flies, bristle shape is found to be incompletely dominant with wild being homozygous (+,+), mildly bent being heterozygous (+,b) and fully bent bristles being homozygous (b,b). For mandible size, wild type is heterozygous (+,m), short is homozygous (+,+) and long is homozygous (m,m). Assume that two mildly bristled, wild mandibled flies (standard F1 cross) are mated, how many of their 432 progeny would you expect to be wild bristled, short mandible?

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genes that are likely to be inherited together because they are physically close to one another on the same chromosome; the physical relationship between genes

Linked Genes

The Dihybrid Recessive Backcross is the primary cross that we will use throughout this laboratory to examine linkage

True

A mating between two organisms with different variations at one genetic locus of interest

monohybrid cross

chi-squared formula

sum of (observed-expected)^2/expected

In a recent study of cat food preferences between salmon and tuna. 62 cats chose tuna and 53 cats chose salmon. Use chi-squared analysis to determine if this sample fits an expected ratio of 1:1. The observed Chi-squared calculated from these data is __________?

0.7

In the previous chi-squared problem involving cat food preferences, how many degrees of freedom are there?

1

In peas, Round seeds are dominant over Wrinkled, and yellow is dominant over Green. A wrinkled, yellow (aaBb) plant is crossed with a round, yellow (AaBb) plant and a large number of offspring are produced. Given the results below, calculate the overall chi-squared (observed) value for these data. Hint: you will first need to determine the expected Phenotypic ratio for this cross. Offspring Phenotypes 291 Wrinkled, Yellow 110 Wrinkled, Green 311 Round, Yellow 104 Round

1.48

You cross a 1000 homozygous black bodied fly with a 1000 homozygous wild type fly through the F2 generation. The results of your F2 cross are: 721 Wild Type Flies 238 Black Bodied Flies You anticipate a 3:1 ratio. In completing a chi-squared calculation, what would be your expected values? Expected Value for Black Bodied flies: __________ Expected Value for Wild Types flies: __________

239.75 719.25

__________ is a "signature" ratio for the Recessive Lethal Mode of Inheritance

2:1

Diploid organisms have __________ possible genotypes at each locus.

3

Degrees of freedom: 1 Table value: ?

3.841

Fruit flies have _____ pairs of chromosomes.

4

Degrees of freedom: 2 Table value: ?

5.991

Degrees of freedom: 3 Table Value: ?

7.815

Degrees of freedom: 4 Table value: ?

9.488

In a dihybrid cross, if two heterozygotes (for both genes) are crossed once, what will be the expected phenotypic ratios? (In the following order: dominant for both traits; dominant for the first trait recessive for the second; recessive for the first trait and dominant for the second; recessive for both traits)

9:3:3:1

In fruit flies, Wild wing shape is dominant over Crumbled wing shape. Wild eye shape is dominant over Eyeless eye shape. using the Electronic Fly Colony you select the following Parental cross. Wild, Wild Male x Crumpled, Eyeless Female. Select the 2 genotypes that would correspond to these phenotypes

AABB male aabb female

You cross 1000 fruit flies with the genotype Aa and obtain the following results: AA: 208 Aa: 511 What mode of inheritance best fits these results?

Lethal Alleles

Assume that allele A is dominant to a, and B is dominant to b. Match each of the following crosses with the expected phenotypic ratio AaBb x aabb: __________ Aabb x AaBb: __________ AaBb x AaBb: __________

AaBb x aabb: 1:1:1:1 Aabb x AaBb: 3:1:3:1 AaBb x AaBb: 9:3:3:1

Expression of the heterozygote phenotype results in BOTH phenotypes being expressed

Codominance

A mating between two organisms with different variations at two genetic loci of interest

Dihybrid cross

Imagine you are conducting an experiment where you hypothesize that apples weigh more than bananas on average. After calculating the weight of 100 apples and 100 bananas you find the average weight of apples is 200 grams and the average weight of bananas is 100 grams. You conduct a statistical test and find this difference is significant according to the test. True or False: You have proven that apples weigh more than bananas and this is now scientific fact.

False

The Fly Colony module used this week has a major difference from the previous weeks. Once you select a F1 offspring to use an F2 parent, the program automatically selects the other parent to be a Dihybrid Double Recessive genotype. This choice assures that the expected mendelian assortment ratio will always be 9:3:3:1

False

Allele pairs separate and segregate during gamete formation (meiosis) and randomly unite at fertilization

Law of Segregation

Expression of the heterozygote phenotype forms an intermediate that is distinct from parents

Incomplete Dominance

When new combinations of the genes in the progeny are formed due to crossing over between genes present on homologous chromosomes

Incomplete Linkage

If the gene for pea color is inherited separately from the gene for pea shape, and thus the allele occurrence for one trait does not affect the other, then this demonstrates the law of __________.

Independent Assortment

Linkage is considered to be a violation of Mendel's Principle of __________.

Independent Assortment

the alleles of two (or more) different genes get sorted into gametes completely independently of one another

Law of independent assortment

Alleles that cause the death of the organism that carries them and are usually a result of mutations in genes that are essential for growth or development

Lethal Alleles

Diploid organisms have a limited number of potential crosses. These crosses are referred to as: __________

Mendel's Big Six

Manner in which a genetic trait or disorder is passed from one generation to the next

Modes of inheritance

Using the __________ Rule, you can multiply the probabilities of two segregation ratios to get the assortment ratio

Product

Phenotypic expression of an allele that is dependent on the gender of the individual and is directly tied to the sex chromosome

Sex Linkage

When performing a __________ and the F2 generations yield significantly different results, it is likely that the trait is sex linked.

Reciprocal cross

the rearrangement of genetic material, especially by crossing over in chromosomes or by the artificial joining of segments of DNA from different organisms.

Recombination

The basic dominant/recessive relationship is also commonly referred to as __________

Simple mendelian

You have performed a dihybrid recessive backcross, and you find that you do NOT get a 1:1:1:1 ratio. This means:

The genes are linked- they are on the same chromosome

In 3-point mapping what are the double cross overs?

The least amount of offspring produced

After setting up a dihybrid backcross, if you fail to reject your null hypothesis, what can you infer about the linkage of loci in question?

The loci are assorting independently

In 3-point mapping what are the parentals?

The most amount of offspring produced

All loci located on Chromosome Pair 1 of fruit flies would exhibit sex-linked mode of inheritance

True

The phenotype of the flies most commonly captured in "the wild" is referred to as the __________.

Wild type

The alternative forms of a gene are known as __________

alleles

one of two or more alternative forms of a gene that arise by mutation and are found at the same place on a chromosome.

alleles

presence of different sex chromosomes

lygaues mode

A person with the phenotype of AB for blood type has the genotype AB. What is the relationship between the A allele and B allele?

co-dominant

What type of dominance is demonstrated by the progeny expressing the phenotype of both parents?

codominance

When two loci are so close together that alleles of these loci are never separated by crossing over

complete linkage

the exchange of genes between homologous chromosomes, resulting in a mixture of parental characteristics in offspring.

cross over

Phenotype 1 is dominant to phenotype 2 IF the heterozygote has phenotype 1

dominant

Continuing with the chi-squared cat food preference question, what is the final verdict of the chi-squared using a p value of 0.05 and degrees of freedom of 1.

fail to reject

If chi-squared value is less than the table value

fail-to-reject

the part of the genetic makeup of a cell, and therefore of any individual, which determines one of its characteristics

genotype

refers to a particular gene having two different alleles of homologous chromosomes

heterozygous

a gene inherited in two species from a common ancestor

homolog

Refers to a particular gene that has identical alleles on homologous chromosomes

homozygous

For the Mendelian option, the Fly Clone program is designed so that the F1 progeny are all heterozygotes. This result stimulates exactly what happens if new ere crossing real flies and occurs because one Parent is __________ dominant while the other is selected to be __________ recessive.

homozygous/ homozygous

The reduction in the probability of occurrence of crossover at one location on a chromosome due to crossover occurring in another location

interference

The position of a gene or mutation on a chromosome.

loci

The set of observable characteristics of an individual resulting from the interaction of its genotype with the environment

phenotype

What do you call the physical expression of a gene?

phenotype

Phenotype 2 is recessive to phenotype 1 IF the heterozygote has phenotype 1

recessive

The frequency with which a single chromosomal crossover will take place between two genes during meiosis

recombination frequency

If the chi-squared value is more than the table value

reject

When each parent has on mutant allele and one wild type allele, the configuration is referred to as __________

trans or repulsed