AP Biology Meiosis Questions

What is meiosis?

Meiosis is a specialized cell division process that reduces a cell's chromosome number by half, creating four genetically unique haploid cells (sperm or eggs) from one diploid parent cell

How do the parent cells compare to the daughter cells in meiosis?

Each daughter cell contains half the number of chromosomes as the original parent cell

What is the function of meiosis?

To produce genetically unique haploid cells (sperm and egg) for sexual reproduction

How is the chromosome number reduced through the process of meiosis from one generation to the next?

Meiosis reduces chromosome number by halving it through two rounds of cell division (Meiosis I & II) after one DNA duplication

What are the FOUR phases of Meiosis I?

Prophase I, Metaphase I, Anaphase I, Telophase I

Describe Prophase I

• Homologous chromosomes pair up and condense

• Synapsis occurs and chiasmata forms

• Meiotic spindle forms

• Centrosomes separate

• Crossing over occurs

Describe Metaphase I

• Meiotic spindle fibers align the homologous pairs of chromosomes at the metaphase plate

• Independent assortment occurs

Describe Anaphase I

• Homologous chromosomes separate but sister chromatids remain attached

• Meiotic spindle fibers pull chromosomes towards poles

Describe Telophase I

• Meiotic spindle breaks down

• 2 haploid daughter cells are formed

What is the ploidy of the daughter cells after Meiosis I?

Haploid (n)

What are the FOUR phases of Meiosis II?

Prophase II, Metaphase II, Anaphase II, Telophase II

Describe Prophase II

• Meiotic spindle forms

• Sister chromatids connected at the centromere attach to the spindle

Describe Metaphase II

• Chromosomes align along the metaphase plate

• The kinetochore of each chromatid is attached to a microtubule extending from the poles

Describe Anaphase II

• Proteins at the centromeres break down

• Sister chromatids are pulled apart towards opposite poles

Describe Telophase II

• Meiotic spindle breaks down

• Chromatids decondense

• Four haploid daughter cells are formed, each w/ an unduplicated chromatid

What is the role of Meiosis II?

To separate the sister chromatids in the two haploid cells produced by Meiosis I, resulting in four genetically different, single-chromatid haploid cells

What is the ploidy of the daughter cells after Meiosis II?

Haploid (n)

Identify 3 differences between Meiosis I and Meiosis II

Meiosis I separates homologous chromosomes, involves crossing over, and reduces the chromosome number (diploid to haploid), while Meiosis II separates sister chromatids, has no crossing over, and resembles mitosis, resulting in four genetically unique haploid cells

Identify which parts of meiosis result in the reduction of chromosome number

Anaphase I

Describe the daughter cells resulting from mitosis

The daughter cells are genetically identical to the parent cell and each other

Describe the daughter cells resulting from meiosis

The daughter cells are genetically different from the parent cells and each other

Identify three similarities between mitosis and meiosis

Cell division and stages, DNA replication, chromosome separation mechanism

Identify three differences between mitosis and meiosis

Meiosis has synapsis and crossing over; the alignment of homologous pairs at the metaphase plate instead of individual chromosomes; and the separation of homologs during Anaphase I

A human cell containing 22 autosomes and a Y chromosome is

A sperm

Homologous chromosomes move towards opposite poles of a dividing cell during

Meiosis I

If the DNA content of a diploid cell in the G₁ phase of the cell cycle is represented by x, then the DNA content of the same cell at metaphase of meiosis I would be

2x

If we continued to follow the cell lineage from question 3, the DNA content of the cell at metaphase of Meiosis II would be

x

Humans have a diploid number (“2n”) of 46. Which of the following statements best predicts the consequence if meiosis did not occur during gametogenesis?

The chromosome number would double with each generation

The figure below shows several steps in the process of bacteriophage transduction in bacteria. Which of the following explains how genetic variation in a population of bacteria results from this process?

DNA of the recipient bacterial chromosome undergoes recombination with DNA introduced by the phage from the donor bacterium, leading to a change in the recipient’s genotype

In 1944 Avery, MacLeod, and McCarty performed transformation experiments using live, harmless bacteria and extracts from virulent bacteria treated with various enzymes. Which of the following enzymes were used and why?

Proteases and RNases to rule out protein and RNA as the transforming factors

Which of the following does NOT increase variation in gamete formation?

Condensation of chromatin

This process involves homologous chromatids exchanging genetic material to increase genetic diversity.

Crossing over

In animals, traits determine by the mitochondrial DNA are inherited from the

Mother

Describe the process of nondisjunction.

Homologous chromosomes or sister chromatids remain attached during anaphase

When does the process of independent assortment take place?

Metaphase I

When does the process of crossing over take place?

Prophase I

What phase of meiosis describes the law of segregation?

Anaphase I

Describe why a male is more likely to be affected by a sex-linked trait?

Males only have one X chromosome