Topic 7 Cell Cycle: Meiosis #43-76 (copy)

heredity

Transmission of physical traits from one generation to the next.

variation

Differences in appearance that offspring show from parents and siblings

genetics

Scientific study of heredity and variation

genes

Segments of DNA that are the units of heredity.

locus

The specific site of a particular gene on its chromosome.

asexual reproduction

A method of reproduction in which one parent produces a genetically identical offspring.

clone

An individual that is genetically identical to its parent.

sexual reproduction

A method of reproduction in which two parents give unique combination of genes to offspring.

karyotype

A display of the chromosome pairs of a cell arranged by size and shape.

homologous chromosomes

A pair of chromosomes of the same length, centromere position, and staining pattern that possess genes for the same characters at corresponding loci.

sex chromosomes

Chromosomes involved in the determination of the sex (gender) of an individual.

autosomes

chromosomes that are not directly involved in determining the sex of an individual

diploid cell

A cell having two sets of homologous chromosomes

haploid cell

A cell with only one set of chromosomes

fertilization

Union of haploid gametes to produce a diploid zygote.

zygote

Fertilized egg that carries one set of chromosomes from each parent.

meiosis

A type of cell division in sexually reproducing organisms that results in cells with half the number of chromosome sets as the original cell.

alternation of generations

A life cycle in which there is both a multicellular diploid form and a multicellular haploid form. Characteristic of plants.

meiosis I

The division of meiosis that separates the homologous pairs of chromosomes.

meiosis II

The division of meiosis that separates the sister chromatids.

synapsis

The side by side pairing of homologous maternal and paternal chromosomes at the start of meiosis.

crossing over

Exchange of genetic material between homologous chromosomes during prophase I of meiosis

recombinant chromosome

A chromosome created when crossing over combines the DNA from two parents into a single chromosome.

independent assortment of chromosomes

The random distribution of maternal and paternal chromosomes into gametes during meiosis.

random fertilization

Source of genetic variation caused by the extremely large number of possible sperm & egg combinations.

prophase I

Phase of meiosis in which chromosomes condense, homologous chromosomes pair up, crossing over occurs, the spindle is formed, and the nuclear envelope breaks apart.

metaphase I

Phase of meiosis in which paired homologous chromosomes (tetrads) align at the center of the cell.

anaphase I

Phase of meiosis in which the homologous chromosomes are separated (the tetrad is split) and pulled to opposite sides of the cell.

telophase I

Phase of meiosis in which two nuclei with the haploid number of chromosomes form.

cytokinesis

Division of the cytoplasm during cell division.

Prophase II

Phase of meiosis in which the spindle begins to form and attach to the chromosomes in preparation to separate the sister chromatids.

metaphase II

Phase of meiosis in which chromosomes line up along the equator of the cell in preparation to separate the sister chromatids.

anaphase II

Phase of meiosis in which the spindle microtubules shrink and pull the sister chromatids to opposite sides of the cell.

telophase II

Phase of meiosis in which new nuclei form in the four new haploid daughter cells.