Mitosis

Somatids

Body cells

Gametes

Sex cells

Another name for mitosis

Equational cell division

Ploidy

The number of complete sets of chromosomes in a cell

Interphase

Preparatory phase, has four main phases: G0, G1, S, G2

G0 stage

The resting phase. Cells may or may not enter this phase, depending on conditions. Cells are metabolically active but not in the cell cycle. Helps maintain tissue homeostasis and prevents unnecessary cell division to conserve energy and resources

Quiescent stage

Temporary G0 stage entry

Senescent Stage

Permanent G0 stage entry

G1 stage

Cell grows in size and synthesizes proteins. It is metabolically active. All cell organelles except DNA are duplicated

G1 checkpoint

The restriction point that allows the cell to ensure that it has enough nutrients, energy, and favorable conditions to commit to DNA replication

S stage

DNA is replicated. Centrosomes are replicated

G2 phase

The cell grows more to hold all the duplicated contents. Prepares the cell for M phase

M phase

The mitosis phase where the actual cell division happens

Karyokinesis

The division of the nucleus

Cytokinesis

The division of cytoplasm

Prophase

The longest phase. Chromatin condenses into visible chromosomes, each with 2 sister chromatids attached at the centromere. The nuclear membrane starts to break down, organelles like nucleolus, golgi, and ER disappear. The duplicated centrosomes move to opposite poles and spindle fibers start to emerge

Chromatin

A network of DNA and proteins

Spindle fibers

Small fibers that emerge from the microtubules of a centriole which connect to chromosomes at the centromere

Metaphase

The chromosomes arrange end to end at the equator of the cell

Metaphase plate

an imaginary plane that forms during metaphase where chromosomes align in the middle of the cell before being separated 

Anaphase

Spindle fibers separate the sister chromatids. The resulting single chromatid becomes an independent chromosome. Each half moves towards opposite poles. The single strand chromosomes make a V-shape as they go through the cytoplasm

Telophase

Final stage. A nuclear membrane again forms around each pole. Each set of chromosomes decondense into chromatin. Spindle fibers disassemble. The duplicated organelles reappear

Meiosis

A type of cell division that produces four genetically varied haploid cells from a single diploid parent cell. It occurs to form gametes (sex cells)

Meiosis I — Meiosis II

First division. Also called reduction division. Diploid cell becomes haploid. —- Second division. Also called equational division. Ploidy doesn’t change

Interphase (Meiosis)

Chromatin threads replicate and two sister chromatids are formed which are attached at the centromere. Centrioles divide.

Prophase I

Chromatin condenses to form chromosomes. Homologous chromosomes pair up (synapsis). Crossing over occurs where chromosomes exchange DNA at points called chiasmata. The half that underwent synapsis is recombinant and the other is non-recombinant. Non-recombinant carries same genes as parent. Centrioles move to opposite poles and spindle fibers fan out

Homologous chromosomes

Chromosomes that have the same shape, size, and genes

Synapsis

The pairing of two homologous chromosomes; one from the father and one from the mother

Crossing over

The exchange of genes between homologous chromosomes 

Chiasmata

The point at which crossing over occurs

Recombinant —- Non-recombinant

The chromatid that underwent crossing over —- The chromatid that didn’t undergo crossing over, carrying the same gene as the parent

Bivalent or Tetrad

The structure formed when two homologous chromosomes pair up

Metaphase I

All tetrads arrange at the equatorial plane. Each chromosome is attached to a spindle fiber

Anaphase I

Homologous chromosomes are pulled to the opposite poles (not sister-chromatids). This halves the number of chromosomes, forming two haploid regions

Telophase I

Each half of a tetrad reach opposite poles. Nuclear membrane forms around each pole

Cytokinesis I

The cytoplasm of the cell cleaves into two, producing two haploid daughter cells. Centeromeres again duplicate in each cell; two cells and four centromeres

Prophase II

The two pairs of duplicated centrioles move to opposite poles. Nuclear membrane disappears, spindle fibers emerge

Metaphase II

Chromosomes arrange at the equatorial plane

Anaphase II

Spindle fibers attach at the centromere and pull the sister chromatids apart

Telophase II

The spindle fibers disappear. Nuclear membrane reappears at poles. Nucleolus forms. Chromosomes decondense into chromatin.

Cytokinesis II

Cleavage forms and two daughter cells are produced. The ploidy is maintained, marking the end of meiosis II