life science grade7 chpt 4 reproduction

a type of reproduction in which the genetic materials from two different cells combine, producing an offspring.

reproductive organs

the female sex cell

forms in the ovary

the male sex cell

forms in the testis

process in which an egg cell and sperm cell join together.

produces a new cell (zygote)

the new celll that forms from fertilization

mitosis and cell division

body cells (similar chromosomes occur in pairs)

sex cells

`cells that have pairs of chromosomes

pairs of chomosomes that have genes for the same traits arranged in the same order.

because one chromosome is inherited from each parent

if a zygote has too many or too few chromosomes it will not develop properly

cells that have only one chromosome from each pair

In a "diploid" cell, there are two copies of each chromosome In a "haploid" cell, there's only one copy of each chromosome.

Most of your body's cells are diploid. Only the gametes, the sperm (in men) and the eggs (in women) are haploid

Diploid cells reproduce by mitosis

Haploid cells are a result of the process of meiosis

meiosis

one diploid cell divides and makes four haploid sex cells

meiosis occurs only during the formation of sex cells

• interphase:
• cell grows and duplicates chromosomes

prophase I

metaphase I

anaphase I

telophase I

duplicated chromosomes condense

homologous chromosomes form pairs

membrane around nucleus breaks apart

nucleolus disappears

homologous chromosome pairs line up in middle of cell

spindle fiber attaches to each chromosome

chromosome pairs separate and are pulled toward opposite ends of cell

(sister chromatids stay together)

nuclear membrane forms around each group of duplicated chromosomes

cytoplasm divides through cytokinesis, making two daughter cells

sister chromatids remain together