apoptosis

programmed cell death that is a normal part of development

chromosome

A discrete, continuous molecule of DNA wrapped around protein. 

What is the difference between chromosomes in Eukaryotic cells and Prokaryotic cells?

• Eukaryotic cells contain multiple linear chromosomes
• Prokaryotic cells contain one circular chromosome

Chromatin

DNA (nucleic acids) and its associated proteins in the nucleus of a eukaryotic cell

nucleosomes

the basic unit of chromatin; consists of DNA wrapped around eight histone proteins

chromatids

a continuous strand of DNA comprising one-half of a replicated chromosome

centromere

small section of a chromosome where sister chromatids attach to each other

diploid

containing two different copies of each chromosome, one from each parent; also called 2n

haploid

containing one copy of each chromosome; also called 1n

gametes

a sex cell; sperm or egg

germ cells

cell that gives rise to gametes in an animal

(occur only in the ovaries and testes)

somatic cells

body cell that does not give rise to gametes (eggs or sperm)

What are some examples of somatic cells?

leaf cells, root cells, skin cells, and neurons

 meiosis

division of genetic material that halves the chromosome number and yields genetically variable gametes

mitosis

division of genetic material that yields two genetically identical cells

cell cycle

sequence of events that occur in an actively dividing cell

interphase

stage preceding mitosis or meiosis, when a cell carries out its function, replicates its DNA, and synthesizes proteins, lipids, and carbohydrates

cytokinesis

distribution of cytoplasm into daughter cells in cell division

G-0 phase

resting place of the cell cycle in which the cell continues to function but does not divide

G-1 phase

gap stage of interphase in which the cell grows and carries out its basic 

G-2 phase

gap stage of interphase in which the cell synthesizes and stores membrane components and spindle proteins

S phase

the synthesis phase of interphase, when DNA replicates

mitotic spindle

a structure of microtubules that aligns and separates chromosomes in mitosis

centrosomes

part of the cell that organizes the mitotic spindle

kinetochores

proteins that attach the chromosomes to the spindle

prophase I

prophase of meiosis I, when chromosomes condense and become visible, and crossing over occurs.

prophase II

prophase of meiosis II, when chromosomes condense and become visible 

prometaphase

stage of mitosis just before metaphase, when the nuclear membrane breaks up and spindle fibers attach to kinetochores

metaphase I

metaphase of meiosis I, when homologous chromosome pairs align down the center of a cell

metaphase II

metaphase of meiosis II, when replicated chromosomes align down the center of a cell

anaphase I

anaphase of meiosis I, when spindle fibers pull homologous chromosomes toward opposite poles of the cell

anaphase II

anaphase of meiosis II, when centromeres split and spindle fibers pull sister chromatids toward opposite poles of the cell

telophase I

telophase of meiosis I, when homologs arrive at opposite poles

telophase II

telophase of meiosis II, when chromosomes arrive at opposite poles and nuclear envelopes form

cleavage furrow

in animals, the initial indentation between daughter cells in mitosis

Describe the cytokinesis of a plant cell..

Plant cells must construct a new cell wall that separates the two daughter cells. The first sign of this cell wall is a line separating the forming cells called a cell plate 

growth factor

a protein that binds a specific receptor type on certain cells, starting a chain reaction of chemical messages that signals the cell to divide

telomeres

the tip of a eukaryotic chromosome

telomerase

enzyme that extends telomeres, enabling cells to divide continuously

tumor

abnormal mass tissue