Mitosis

List the phases of mitosis in order

1. Prophase

2. Prometaphase

3. Metaphase

4. Anaphase

5. Telophase

Cell division

Process of a single (parent) cell dividing or splitting into two or more daughter cells

What are the 3 main types of cell division?

• Binary fission - prokaryotic cell division

• Mitosis - Eukaryotic cell division producing somatic cells (body cells)

  • Human somatic cells are diploid (2n) since they have 2 copies of every chromosomes

• Meiosis - Eukaryotic cell division producing gametes (sex cells)

  • Human gametes are haploid (n) because they have 1 copy of every chromosome

Asexual vs. Sexual Reproduction

• Asexual - No sexual activity (only 1 parent involved)

  • Only one source of DNA = genetically identical offspring

• Sexual - Sexual activity (2 parents involved)

  • Two sources of DNA = genetically diverse offspring

Why is cell division important?

Important for asexual reproduction, fetal development (growth), and tissue repair

What do all cells have to do before they can divide?

They must replicate its DNA so each daughter cell can get a copy of the DNA

Genome

A complete set of all the cells DNA

Genetic material

Molecules that determine the inherited traits of an organism (usually DNA)

Histones

Proteins that associate with DNA to form nucleosomes

Nucleosomes

Units of 8 histone proteins at the core with DNA wrapped around it

How can nucleosomes take on different forms?

It can take on different forms if the cells is non-dividing or dividing

Chromatin vs. Chromosomes

• Chromatin - loosely packed/coiled nucleosomes in non-dividing cells

• Chromosomes - tightly packed, highly condensed, nucleosomes in a dividing cell

  • Made up of chromatin

DNA Replication

• DNA replication - produces an exact copy of all the DNA in a cell

  • Converts unreplicated chromosomes to replicated chromosomes with 2 identical chromatids

Chromatid

½ of a replicated chromosome joined to another chromatid at the centromere

Cell cycle

• Cell cycle - a representation of the events that a cell performs from the moment it is formed to when it divides

• Has 2 major phases

  • Interphase

  • Mitotic phase

Interphase and mitotic phase

• Interphase - a non-dividing phase for cell growth, DNA replication, and production of organelles/enzymes

  • Has 4 sub-phases - G0, G1, S, and G2

• Mitotic phase - a dividing phase that separates the genetic material while producing multiple cells

  • Mitosis + cytokinesis

  • Has 5 phases - prophase, prometaphase, metaphase, anaphase, and telophase

4 sub-phases of interphase

1. G0 - a non-divding phase where cells do not replicate their DNA nor prepare for divisiob

2. G1 (growth) - cell performs its normal functions, growing and producing organelles, enzymes, and proteins

3. S (synthesis) - DNA synthesis and replication producing replicated chromosomes with 2 sister chromatids

   1. Centrosome is also replicated

4. G2 (growth) - cell continues growth and produces new proteins for M phase

Centrosomes and mitotic spindles

• Centrosomes - a cytoplasmic protein that forms/organizes the mitotic spindle during mitosis

• Mitotic spindle - microtubule proteins of the cytoskeleton that coordinates division of chromosomes

Mitosis

• Mitosis - the asexual process of dividing the nucleus and the genetic material of a somatic cell (body cell)

• Has 5 phases

  • Prophase

  • Prometaphase

  • Metaphase

  • Anaphase

  • Telophase

Stages of mitosis

• Prophase

  • Loosely coiled chromatin condenses to form chromosomes with sister chromatids linked at the centromere

  • Nucleolus disappear from the nucleus

  • Two centrosomes migrate to opposite poles of the cell and begin forming the mitotic spindle

• Prometaphase (late prophase)

  • Nuclear envelope degrades, exposing chromosomes to the cytoplasm

  • Mitotic spindle links to chromosomes by attaching to kinetechore proteins in the centromere

• Metaphase

  • Mitotic spindles align chromosomes in the middle of the cell in a single row

  • The middle of the cell is called the metaphase

• Anaphase

  • Sister chromatids are pulled apart toward opposites ends of the cell

  • Some parts of the mitotic cell shorten, pulling chromatids apart, whereas others lengthen, stretching the cell

• Telophase

  • Reverse of prophase and prometaphase

  • Chromosomes revert back to chromatin

  • Mitotic spindle degrades

  • Nucleolus and nuclear envelope reform at each end of the cell to form 2 nuclei