Science 4.1

sexual reproduction

a type of reproduction in which genetic material from two different cells combine to produce an offspring.

sex cells

cells that combine during sexual reproduction; formed in reproductive organs.

egg

female sex cell; formed in an ovary.

sperm

male sex cell; formed in a testis.

fertilization

a reproductive process during which an egg cell and a sperm cell join to form a zygote.

zygote

the new cell that forms when a sperm cell fertilizes an egg cell.

diploid cells

cells with pairs of chromosomes; one comes from your mother and the other comes from your father.

homologous chromosomes

pairs of chromosomes that have genes for the same trait arranged in the same order; one from each parent.

haploid cells

cells that contain only one chromosome from each pair.

meiosis

a type of cell division that produces haploid sex cells; only occurs in reproductive organs.

genetic variation

the diversity in gene frequencies, which occurs in all organisms that reproduce sexually.

Cavendish bananas

a variety of bananas that are clones of each other and susceptible to diseases due to lack of genetic diversity.

Meiosis I

the first division of meiosis where tetrads are separated.

Meiosis II

the second division of meiosis where sister chromatids are separated.

prophase I

stage of meiosis I where duplicated chromosomes condense and homologous chromosomes form tetrads.

metaphase I

stage of meiosis I where pairs of homologous chromosomes are brought to the center of the cell.

anaphase I

stage of meiosis I where homologous pairs are pulled apart.

telophase I

stage of meiosis I where cytoplasm divides and nuclear envelopes form.

prophase II

stage of meiosis II where the nuclear envelope disintegrates and spindle apparatus forms.

metaphase II

stage of meiosis II where sister chromatids are brought to the center of the cell.

anaphase II

stage of meiosis II where sister chromatids are pulled apart.

telophase II

stage of meiosis II where cytoplasm divides and nuclear envelopes reform.

crossing over

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

random assortment

the process during meiosis where chromosomes are randomly distributed into gametes.

mitosis

the process that creates two identical diploid body cells by duplicating the chromosomes and dividing the nucleus once.