Cell Cycle & Mitosis

Chromosome Theory &

Gene

A segment of DNA that codes for a protein or RNA product. Genes comprise both structural and regulatory elements.

chromosome

A complex of DNA-binding proteins and DNA. Chromosomes are circular in most bacteria and archaea and linear in eukaryotes.

haploid number

The number of different types of chromosomes present in a cell. Haploid number is indicated with an n. Humans have 23 different types of chromosomes, so in that species n = 23.

ploidy

The number of each type of chromosome present in a cell. Ploidy is written as a number before the n that presents haploid number. Humans, for example, are 2n, meaning that they have two of each type of chromosomes

haploid

Having one of each type of chromosome

diploid

Having two of each type of chromosome

homologous chromosomes/homologs

Different versions of the same chromosome type

replicated chromosomes

A chromosome comprised of two identical DNA molecules, joined together

sister chromosomes

The identical copies in a replicated chromosome

mitosis

A process in eukaryotes that is responsible for distributing a copy of each chromosome to each daughter cell. It occurs after chromosomes have been replicated and prior to the physical division of the parent cell into two daughter cells.

m phase

The portion of the cell cycle when mitosis and cell division occur

interphase

The portion of the cell cycle when growth and DNA replication occurp

prophase

The initial phase of mitosis, when replicated chromosomes condense and the nuclear envelope breaks down

metaphase

The middle phase of mitosis, when replicated chromosomes move to the middle of the cell

anaphase and telophase

The late phases of mitosis, when sister chromatids separate and one of each type of chromosome ends up at either end of the parent cell, then nuclear envelopes re-form around each set of chromosomes.

germ cells

Cells that directly give rise to sperm or eggs, or are sperm or eggs themselves.  Germ cells undergo meiosis to produce haploid daughter cells.

somatic cells

Cells that form the body, and that only undergo mitosis