Biology Unit 7: Meiosis and Reproduction

Trait

A characteristic that an organism can pass on to its offspring through its genes.

Gene

Sequence of DNA that codes for a protein and thus determines a trait

Sister Chromatid

Replicated forms of a chromosome joined together by the centromere and eventually separated during mitosis or meiosis II.

Homologous Chromosomes

Chromosomes that have the same sequence of genes, that have the same structure, and that pair during meiosis.

Somatic Cell

Any of the cells of a plant or animal except the reproductive cells.

Gamete

A mature haploid male or female germ cell that is able to unite with another of the opposite sex in sexual reproduction to form a zygote.

Haploid

An organism or cell having only one complete set of chromosomes.

Diploid

Containing two complete sets of chromosomes, one from each parent.

Fertilization

The action or process of fertilizing an egg, female animal, or plant, involving the fusion of male and female gametes to form a zygote.

Zygote

A diploid cell resulting from the fusion of two haploid gametes; a fertilized ovum.

Meiosis

Cell division that produces reproductive cells in sexually reproducing organisms

Meiosis II

The second phase of meiosis consisting of chromatids separating, along with the two diploid cells splitting. in two

Crossing over

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

Tetrad

Each pair of homologous chromosomes.

Independent Assortment

One of Mendel's principles that states that genes for different traits can segregate independently during the formation of gametes

Random Fertilization

Source of genetic variation caused by the unlimited number of possible sperm & egg combinations

Sepal

A modified leaf in angiosperms that helps enclose and protect a flower bud before it opens.

Petal

A modified leaf of a flowering plant; are the often colorful parts of a flower that advertise it to insects and other pollinators.

Stamen

The male reproductive organ of a flower consisting of an anther and a filament

Anther

The part of a stamen that contains the pollen.

Filament

Supports/ holds up the anther

Pistil

The female reproductive part of a flower

Stigma

Female part of the plant and is the sticky top surface of the flower, to which pollen adheres.

Style

The stalk of a flower's carpel, with the ovary at the base and the stigma at the top.

Ovule

Female reproductive structure of a seed plant where the haploid egg develops

Pollination

The transfer of pollen from male reproductive structures to female reproductive structures in plants

Pollen Tube

A tube that forms after germination of the pollen grain and that functions in the delivery of sperm to the ovule.

Seed

Plant embryo and a food supply encased in a protective covering

Fruit

A mature ovary of a flower that protects dormant seeds and aids in their dispersal.

Sperm

Male sex cell (gamete)

Testes

The place where sperm and testosterone are produced

Scrotum

External sac that contains the testes (used for temperature regulation)

Epididymis

A long, coiled duct on the outside of the testis in which sperm mature

Vas Deferens

The duct that conveys sperm from the testicle to the urethra.

Semen

A thick fluid containing sperm and other secretions (seminal fluid) from the male reproductive system

Seminal Vesicles

Two small glands that secrete a fluid rich in sugar that nourishes and helps sperm move

Prostate Gland

A gland in males that contributes to the seminal fluid

Urethra

tube that carries urine from the bladder and semen from the vas deferens to the outside of the body.

Penis

Male reproductive organ

Egg

female gamete

Ovary

Organ of the female reproductive system in which eggs and estrogen are produced.

Oviduct

Fallopian tube; tube that carries eggs from an ovary to the uterus

Uterus

Female organ of reproduction used to house the developing fetus.

Cervix

opening to the uterus that can dilate during childbirth

Vagina

A muscular, elastic passageway that extends from the uterus to the outside of the body

Placenta

A structure that allows an embryo to be nourished with the mother's blood supply

Umbilical Cord

A flexible cordlike structure containing blood vessels and attaching a human or other mammalian fetus to the placenta during gestation.