Cellular Reproduction Terms

cell division

the process in reproduction and growth by which a cell divides to form daughter cells

Chromosomes

threadlike structures made of DNA molecules that contain the genes

asexual reproduction

single-celled organisms reproduce by dividing in half, producing offspring that are genetic replicas of the parent cell

clone

a group of geneticallyidentical individuals

sexual reproduction

A reproductive process that involves two parents that combine their genetic material to produce a new organism, which differs from both parents

gametes

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.

diploid 2n

2 sets of homologous chromosomes

haploid n

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

triploid 3n

three sets of chromosomes

homologous chromosomes

Chromosomes that have the same sequence of genes and the same structure

allele

Different forms of a gene

genotype

genetic makeup of an organism

phenotype

physical characteristics of an organism

chromatin

Clusters of DNA, RNA, and proteins in the nucleus of a cell

Histones

proteins used to package DNA in eukaryotes

nucleosomes

DNA wrapped around histone proteins.

sister chromatids

Identical copies of a chromosome; these are created during the S subphase of interphase.

centromere

2 sister chromatids are joined together tightly at a narrow "waist''

cell cycle

series of events in which a cell grows, prepares for division, and divides to form two daughter cells

interphase

Cell grows, performs its normal functions, and prepares for division; consists of G1, S, and G2 phases--90% of cell cycle

DNA replication

Process of copying DNA before cell division.

mitotic (m) phase

The phase of the cell cycle that includes mitosis and cytokinesis.

mitosis

cell division in which the nucleus divides into nuclei containing the same number of chromosomes

cytokinesis

division of the cytoplasm

prophase

Chromosomes become visable, nuclear envelop dissolves, spindle forms from centrosomes

Metaphase

chromosomes line up across the center of nucleus & mitotic spindle binds to centromere

anaphase

chromosomes separate and move to opposite ends of the cell

telophase

Nuclear envelop reforms, cytokinesis occurs with cleavage furrow

mitotic spindle

A football-shaped structure formed of microtubules and associated proteins that is involved in the movement of chromosomes during mitosis and meiosis.

microtubes

thin, hollow cylinders made of protein

cleavage, cytokinesis

division of the cytoplasm

contractile ring

A thin band of actin and myosin filaments that wraps around the midsection of an animal cell undergoing cytoplasmic division. It contracts and pinches the cytoplasm in two.

cell plate

A double membrane across the midline of a dividing plant cell, between which the new cell wall forms during cytokinesis.

somatic cell

body cell

karyotype

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

autosomes

22 pairs of matching chromosomes

sex chromosomes

X and Y chromosomes.

life cycle

a multicellular organism is the sequence of generation-to-generation stages, from fertilization to the production of its own offspring

fermentation

Process by which cells release energy in the absence of oxygen

zygote

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

meiosis

the process of cell division that produces haploid gametes in diploid organisms, resembles mitosis, but with two differences.

crossing over

Exchange of genetic material between homologous chromosomes.

nondisjunction

members of a chromosome pair fail to separate at anaphase--producing gametes with abnormal numbers of chromosomes.

trisomy 21

condition in which an individual has three number 21 chromosomes, making 47 chromosomes-- resulting in Down syndrome

cell cycle control system

A cyclically operating set of proteins that triggers and coordinates events in the eukaryotic cell cycle.

cancer

A disease in which some body cells grow and divide uncontrollably, damaging the parts of the body around them.

tumor

mass of rapidly dividing cells that can damage surrounding tissue

benign tumor

a mass of abnormal cells that remains at the site of origin

malignant tumors

spread into neighboring tissues & parts of the body, forming new tumors, and can interrupt organ function

chemotherapy

The use of drugs to treat diseases such as cancer