Biology: Key Concepts in Cell Reproduction and DNA Structure

asexual reproduction

form of reproduction in which offspring arise from only oneparent

sexual reproduction

he combination of genetic material from two individuals tocreate a third individual

gamete

a sex cell; sperm or egg cell

apoptosis

programmed cell death that is a normal part of development

chromosome

a continuous molecule of DNA wrapped around protein in the nucleusof a eukaryotic cell; also, the genetic material of a prokaryotic cell

DNA polymerase

enzyme that adds new DNA nucleotides and corrects mismatchedbase pairs in DNA replication

Ligase

enzyme that catalyzes formation of covalent bonds in the DNA sugar-phosphate backbone

binary fission

type of asexual reproduction in which a prokaryotic cell divides intotwo identical cells

chromatid

one of two identical DNA molecules that make up a replicatedchromosome

centromere

small section of a chromosome where sister chromatids attach to eachother

cell cycle

sequence of events that occur in an actively dividing cell

interphase

stage preceding mitosis or meiosis, when the cell carries out itsfunctions, replicates its DNA, and grows

cytokinesis

distribution of cytoplasm into daughter cells in cell division

cleavage furrow

in dividing animal cells, the indentation that begins the process ofcytokinesis

cell plate

in plants, the materials that begin to form the wall that divides two cells

diploid cell

cell containing two full sets of chromosomes, one from each parent; alsocalled 2n

karyotype

a size-ordered chart of the chromosomes in a cell

somatic cell

body cell that does not give rise to gametes

germ cell

specialized cell that gives rise to gametes

crossing over

exchange of genetic material between homologous chromosomesduring prophase I of meiosis

spindle

a structure of microtubules that aligns and separates chromosomes inmitosis and meiosis

prophase

stage of mitosis when chromosomes condense and the mitotic spindlebegins to form

metaphase

stage of mitosis in which chromosomes are aligned down the center of acell

anaphase

stage of mitosis in which the spindle pulls sister chromatids towardopposite poles of the cell

telophase

stage of mitosis in which chromosomes arrive at opposite poles andnuclear envelopes form