Reproduction

the ability of an individual to produce viable offspring

Asexual reproduction

a single parent produces genetically identical offspring

Binary fission

division of a single parent cell into two genetically identical daughter cells of equal size

Budding

unequal splitting of a parent cell or organism into two genetically identical offspring of unequal size

Fragmentation

a piece of an organism breaks away and becomes another genetically identical individual

Regeneration

replacement of a lost body part

Parthenogenesis

development of an unfertilized egg into a new individual

Sexual reproduction

two parents contribute genetics to produce genetically unique offspring

Fertilization

fusion of a sperm cell with an egg cell

Zygote

a fertilized egg possessing the diploid chromosome number

Diploid number

full chromosome number for a species represented as 2n

Haploid number

half the full chromosome number represented as n

Gametes

sex cells such as sperm and eggs that contain the haploid number

Gonads

sex organs that produce gametes

Testes

male gonads that produce sperm

Ovaries

female gonads that produce eggs

Meiosis

cell division that produces gametes and cuts chromosome number in half

Homologous chromosomes

chromosomes identical in size shape and traits they carry

Autosomes

chromosomes that do not influence gender

Sex chromosomes

chromosomes that determine gender

Tetrad

a pair of duplicated homologous chromosomes consisting of four chromatids

Crossing over

exchange of genetic material between chromatids within a tetrad

Chiasma

the point where crossing over occurs

Independent assortment

random orientation and separation of tetrads during meiosis I

Interphase

preparation period including G1 S and G2

G1 period

no cell growth occurs

S period

DNA synthesis and chromosome duplication

G2 period

no mass production of cell structures

Prophase I

chromosomes thicken nuclear envelope breaks down spindle forms tetrads form crossing over occurs

Metaphase I

tetrads line up along the middle of the cell

Anaphase I

tetrads separate into dyads

Telophase I

formation of two haploid nuclei with duplicated chromosomes

Interkinesis

rest period between meiosis I and II where nothing occurs

Prophase II

chromosomes thicken spindle forms nuclear envelope breaks down

Metaphase II

dyads line up along the middle of the cell

Anaphase II

dyads separate into individual chromatids

Telophase II

formation of four haploid nuclei in four cells

Sister chromatids

identical copies of a chromosome held together by a centromere

Centromere

the region holding sister chromatids together

Spindle fibers

microtubules that move chromosomes

Dyads

duplicated chromosomes after tetrads separate

Spermatogenesis

production of sperm in the testes

Oogenesis

production of eggs in the ovaries

Polar bodies

small nonviable cells produced during oogenesis

Random fertilization

random combination of sperm and egg increasing genetic variation