The world of mitosis! Where one cell splits into 2…

sounds like an inefficient way to do things but sure…¯\_(ツ)_/¯ it works i guess

Cell Division

Why do cells reproduce? What is the point?

Organisms need to reproduce and replace old/damaged cells other organisms would be unicellular¹

Cell division is also needed for sexual reproduction and growth.

Cell Cycle

Eukaryotic cells divide in 2 ways

• Mitosis: divides into 2 daughter cells that are genetically identical to each other and parent cells
• Meiosis: Click here

There is a cell cycle that cells follow, which is known as IPMAT

Rest Phase; Interphase

Cells often stop dividing one they are fully differentiated; specialised cells move from G1 to G0 (resting phases)

Cells may remain in G0 for the rest of its lifetime, or maybe just temporarily

G0 is also the phase in which stem cells wait until their associated body cells need replacing

Mitosis: Dividing and growing

The type of division that makes animals and plants grow is mitosis

A parent cell divides into two daughter cells²

The way which old and damaged cells are replaced

Normally, a cell only contains one copy of each chromosomes - before dividing chromosomes are duplicated

Duplication

Cell chromosomes are usually a long thin strand; but for a part of interphase, they condense and each chromosome duplicates (via DNA replication!) and become 2 strands, each one called a chromatid; the two are joined at the centromere.

During mitosis, the DNA was duplicated into each of the daughter cells.

IPMAT

Interphase [This isn’t officially counted as a stage of mitosis… but some say it is? So if they just say PMAT, they are refering to this as well]

• This stage happens before mitosis; where DNA replicates
• Each chromosome replicates so it contains two identical chromatids
• Organelles rae replicated and cells increase in size by a small amount
• The stages of this are: G1 (growth), G0 (rest), Synthesis (replication), G2 (final check)

Prophase (preparation phase)

• DNA condenses into chromosomes
• Two pairs of centrioles (T like structure) form and move to opposite sides of the cell
• Nuclear membrane breaks down; nucleolus disappears

Metaphase (middle)

• Chromatids become visible
• Chromosomes line up at the centre of the cell; the cell equator
• Spindle fibres attach from poles to the chromosomes at the centromere

Anaphase

• Spindle fibres pull chromosomes aprt
• One chromatid (half a chromosome) moves to each pole
• Chromatids are now called chromosomes again after they are separated 🙄🙄³

Telophase (includes Cytokinesis)

• Two sets of chromosomes form groups at each pole
• DNA packages into DNA membrane and uncoils back into the stringy stuff (scientifically called chromatin; but who cares)
• Nucleolus reforms along with nuclear membrane
• Cytokineses: Furrows develop and deepens until cytoplasm splits into 2 separate daughter cells (basically the cell splits into 2 new cells)

and thats the end! (for now unless you do meiosis)