Mitosis and Meiosis / Cell Cycle

Interphase

G0: resting, where cells are a majority of the time

G1: cell growth

S/Synthesis: DNA is replicated

G2: cell finishes growing

prophase

DNA condenses into chromosomes and organizes

prometaphase

microtubules attach to the chromosomes at the centromere, nuclear membrane dissolves

metaphase

chromosomes line up at the equator

anaphase

microtubules pull chromosomes to poles

telophase

nuclear membrane reforms

Mitosis Checkpoints

G1 checkpoint: make sure cell is ready for mitosis

G2 checkpoint: cell pauses in G2 to make sure DNA is fully replicated and undamaged

metaphase checkpoint: cell pauses pre-anaphase to make sure chromosomes are attached to spindles

tumor suppressors

factors that block progression past a checkpoint (GOOD)

proto-oncogenes

factors that trigger progression past a checkpoint (BAD = pre-cancer)

stem cells

specialized cells meant to enter the cell cycle, job is to produce and divide

haploid

one set of chromosomes

diploid

2 sets of chromosomes

Prophase 1

DNA condenses and forms chromosomes, nuclear membrane dissolves

synapsis/crossing-over occurs

metaphase 1

chromosomes line up at the equator in homologous pairs

anaphase 1

homologous chromosomes separate and are pulled to opposite ends of the cell

telophase 1

Cytoplasm divides, 2 daughter cells are formed

prophase 2

Chromosomes condense, spindles form in each new cell, and spindle fibers attach to chromosomes.

metaphase 2

Chromosomes line up at the equator.

anaphase 2

sister chromatids separate and move to opposite poles

telophase 2 and cytokinesis

cells split into 4 separate haploid/gamete cells

Cleavage Furrow (cytokinesis)

cell cinches

Cell Plate (cytokinesis)

hole in the middle expands to outer edge to separate cells

Budding (cytokinesis)

cell grows off of the cell

Haploid cells can do what else to create gametes?

fuse. once fertilized, creates zygotes

haploid-dominant life cycle

1. haploid organisms produce gametes by mitosis

2. gametes undergo fertilization to produce diploid zygote

3. zygote undergoes meiosis to produce spores

4. spores germinate ad grow to be haploid organisms

diploid-dominant life cycle

1. diploid organisms produce haploid gametes by meiosis

2. haploid gametes undergo fertilization to produce diploid zygote

3. zygote undergoes mitosis to produce diploid organisms

Alternation of Generations

another life cycle, in between diploid and haploid dominant life cycles