Chapter 13

clone

A group of genetically identical offspring.

asexual reproduction

A single parent passes copies of all its genes to its offspring.

Distinguish between the following pairs of terms: a) somatic cell and gamete b) autosome and sex chromosome

A) Somatic cell: Two chromosomes of each type, known as homologous chromosomes. Gamete: Egg and sperm B) Autosome: Chromosomes other than the sex chromosomes. Sex chromosome: Determine the sex of a person: XX= Female, XY= Male

sexual reproduction

An individual receives a unique combination of genes inherited from two parents.

autosome

Chromosomes other than the sex chromosomes.

zygote

Contains both paternal and maternal sets of chromosomes (fusion of egg and sperm).

chiasma

Crossovers are visible later in the stage, where sister chromatid cohesion holds the original sister chromatids together.

sex chromosome

Determine the sex of a person: XX= Female, XY= Male

haploid cell

Gametes, egg and sperm (contain a single set of chromosomes).

Explain how haploid and diploid cells differ from each other. State which cells in the human body are diploid cells differ from each other. State which cells in the human body are diploid and which are haploid.

Haploid cells: Gametes, egg and sperm (contain a single set of chromosomes). Diploid cells: Somatic cells (one from each parent).

Describe two events that occur during Meiosis I but not during Mitosis.

In metaphase I, the metaphase plate is lined horizontally whereas the mitosis has their plate vertically.

recombinant

In prophase I, homologous chromosomes segments of nonsister chromatids are exchanged by crossing over, with genetic combinations of maternal and paternal genes on the same chromosome.

List the phases of meiosis I and meiosis II and describe the events characteristic of each phase.

Meiosis I - Prophase I: Replicated homologous chromosomes. -Metaphase I: Chromosomes line up on the metaphase plate (horizontally). -Anaphase I: Chromosomes separate on opposite poles of the cell. -Telophase I/Cytokinesis: The cleavage furrow forms and the cell is split into two haploid cells. Meiosis II - Prophase II: Sister chromatids are paired up -Metaphase II: Sister chromatids line up on the metaphase plate (vertically) -Anaphase II: Sister chromatids get pulled away by spindle apparatus to opposite poles of the cell. -Telophase II/Cytokinesis: Nuclei form and the cell in split into four haploid cells.

allele

One of two or more forms of a gene.

meiosis I

Separation of homologous chromosomes

meiosis II

Separation of sister chromatids

diploid cell

Somatic cells (one from each parent).

synapsis

The pairing of two homologous chromosomes that occurs during meiosis.

Describe the process of synapsis during prophase I. What happens during this?

The pairing of two homologous chromosomes that occurs during meiosis. The genetic material is rearranged by crossing over between nonsister chromatids.

crossing over

The reciprocal exchange of genetic material between nonsister chromatids during prophase I of meiosis.

homologous chromosomes

Two chromosomes of each type, from each parent.

somatic cell

Two chromosomes of each type, known as homologous chromosomes.