5 Steps to a 5 AP Biology, 2014-2015 Edition

Cell Division ❮ 97

STAGE MITOSIS MEIOSIS

Metaphase I — Chromosome pairs align along
middle of cell, ready to split apart

Anaphase I — Homologous chromosomes split apart

Telophase I — Nuclear membrane reforms; daughter cells
are now haploid (n)

Prophase II — Nucleus disappears, spindle apparatus forms

Metaphase II — Sister chromatids line up at middle

Anaphase II — Sister chromatids are split apart

Telophase II — Nuclei of new cells reform; chromatin
uncoils

Cytokinesis:physical separation of newly formed daughter cells of cell division.

Cell division control mechanisms:

1.Growth factors:factors that when present, promote growth, and when absent, impede

growth.

2.Checkpoints:a cell stops growing to make sure it has the nutrients and raw materials

to proceed.

3.Density-dependent inhibition:cell stops growing when certain density is reached—runs

out of food!!!

4.Cyclins and protein kinases:cyclin combines with CDK to form a structure known as

MPF that pushes cell into mitosis when enough is present.

Haploid(n): one copy of each chromosome.

Diploid(2n): two copies of each chromosome.

Homologous chromosomes:chromosomes that are similar in shape, size, and function.

Spermatogenesis:the process of male gamete formation (four sperm from one cell).

Oogenesis:the process of female gamete formation (one ovum from each cell).

Life cycles:Sequence of events that make up the reproductive cycle of an organism.

• Human:zygote (2n)→multicellular organism (2n)→gametes (n)→zygote (2n)


• Fungi:zygote (2n)→multicellular organism (n)→gametes (n)→zygote (2n)


• Plants:zygote (2n)→sporophyte (2n)→spores (n)→gametophyte (n)→gametes (n)→
  zygote (2n)
  Sources of variation:crossover, 2npossible gametes that can be formed, random pairing of
  gametes.

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