Biology Chapters 11,12,1

Phenotypes like height in humans, which show a continuous distribution, are usually the result of

the action of multiple genes on a single phenotype.

Mutations that affect DNA repair often also affect the accuracy of meiosis. This is because

the proteins involved in the repair of double-strand breaks are also involved in crossing over

Crossing over involves each of the following with the exception of

the transfer of DNA between two sister chromatids

Down Syndrome is the result of trisomy for chromosome 21. Why is this trisomy viable whereas trisomy for most other chromosomes is not?

Chromosome 21 is a small chromosome with few genes so this does less to disrupt the genome.

How does DNA replication differ between mitosis and meiosis?

b. During meiosis, there is only one round of replication for two divisions

During the process of spermatogenesis, a nondisjunction event that occurs during the second division would

be better than the one during first division because only two of the four meiotic products would be aneuploid

Chiasmata form

between homologous chromosomes

What cellular process is responsible for genetic recombination?

crossing over between homologues

During anaphase 1

homologous chromosomes move to opposite poles

Which of the following does NOT contribute to genetic diversity?

metaphase of meiosis II

What occurs during anaphase of meiosis II?

sister chromatids are pulled to opposite poles

bipolar disorder is a complex trait that shows high heritability in twin studies. This best way to analyze the genetics of this would be to use

GWAS to look for associations of genetic variants with bipolar disorder.

A recessive sex-lined gene in humans lead to a loss of sweat glands. A woman heterozygous for this will

Have patches of skin with and without sweat glands.

When you cross true-breeding tall and short tobacco plants you get an F1 that is intermediate in height. When this F1 is self-crossed, it yields an F2 with a continuous distribution of heights. What is the best explanation for these data?

Height is determined by the additive effects of many genes

What property distinguished Mendel's investigation from previous studies?

Mendel quantified his results.

What are homologous chromosomes?

Two genetically similar chromosomes, one from each parent

Mendel's model assumes that each trait is determined by a single factor with alternate forms. We now know this is too simplistic and that

A single gene can affect more than one trait, and traits may be affected by more than one gene.

If the two genes in the previous question showed complete linkage, what would you predict for an F2 phenotypic ratio?

1 red tall:2 pink tall:1 white short

The A and B genes are 10 cM apart on the chromosome. If an A B/a b heterozygote is testcrossed to a b/a b, how many of each progeny class would you expect out of 100 total progeny?

45 A B, 45 a b, 5 A b, 5 a B

How many map units separate two alleles if the recombination frequency is 0.07?

7 cM

In a cross of Aa Bb cc X Aa Bb Cc, what is the probability of obtaining an individual with the genotype AA Bb Cc?

1/16

What is the probability of obtaining an individual with the genotype bb from a cross between two individuals with the genotype Bb?

1/4

The F1 plants from the previous question are allowed to self-fertilize. The phenotypic ratio for the F2 should be

3 purple: 1 white

Japanese 4 o'clock's that are red and tall are crossed to white short ones, producing an F1 that is pink and tall. If these jeans assort independently, and the F1 is self-crossed, what would you predict for the ratio of F2 phenotypes?

3 red tall: 6 pink tall: 3 white tall: 1 red short: 2 pink short: 1 white short

Mendel's Principle of Segregation states that

Alleles of a gene are segregated during gamete formation.

Genetic mapping and GWAS

Are examples of forward genetics.

Which of the following is NOT a distinct feature of meiosis?

Attachment of sister kinetochores to spindle microtubules

Why is the white-eye phenotype always observed in males carrying the white-eye allele?

Because the allele is located on the X chromosome and males only have one X

Structurally, meiotic cohesins have different components than mitotic cohesins. This leads to the following functional difference:

Centromeres remain attached during anaphase I of meiosis

In comparing somatic cells and gametes, somatic cells are...

Diploid with twice the number of chromosomes.

Which of the following genotypes due to nondisjunction of sex chromosomes are lethal?

OY

An organism's __________ is/are determined by its ______________.

Phenotype; genotype

How does maternal inheritance of mitochondrial genes differ from sex linkage?

Since mitochondria are inherited from the mother, females and males are equally affected.

Which phase of meiosis I is most similar to the comparable phase in mitosis?

Telophase I

In an organisms genome, autosomes are

all chromosomes other than sex chromosomes

The F1 generation of the monohybrid cross purple (PP) x white (pp) flower pea plants should

all have purple flowers

At metaphase 1 the kinetochores of sister chromatids are

attached to microtubules from the same pole

Genes that are on the same chromosome can show independent assortment

when they are far enough apart that odd numbers of crossovers are about equal to even.