5. Cell Reproduction & Mitosis

There are 3 Stages that occur before cell division.

1. Interphase

2. Mitosis

3. Cytokinesis

Interphase is made up of 3 Parts: ?

Interphase is made up of 3 Parts:

● G1: Cell Grows and performs normal functions

● S: DNA Replication → creates sister chromatids

● G2: Cell grows more and prepares for mitosis

Mitosis is the process of ?

Mitosis is the process of duplicating the nucleus.

Why might a cell divide?

• To grow more cells

• To repair

What could go wrong when a cell divides

• Mistake copying DNA

• Doesn’t split

• Misalignment of chromosome

Stage 1 of cell cycle?

what?

Stage 1 Interphase

• The longest of all 3 stages

• During this stage, the cell grows, so it can prepare to divide. and share the DNA and organelles between the 2 new cells.

• Stage in which there is No Dividing.

• Nucleus is in one piece

• DNA is stringy → Chromatin

• Makes copies of DNA (Sister chromatids)

• Focus on Growing , & getting ready to divide

How do the cells grow?

and they get there by going through?

How do the cells grow?

• Need water and nutrients to grow

and they get there by going through the cell membrane...

Recall the membrane’s function:

Recall the membrane’s function:

Controls the flow of materials in and out of the cell

How Nutrients (Oxygen, minerals, sugars) flow in membrane

Diffusion

• Movement of particles from high to low concentration

How Water flow in membrane

Osmosis

• Special kind of diffusion of water across the membrance

Stage 2 of cell cycle?:

what?

Stage 2: Mitosis

• This is the stage where the nucleus divides into two. Not the entire cell

Mitosis

If the nucleus is divided in 2: ?

If the nucleus is divided in 2:

● You have 2 copies of the DNA

● You create 2 daughter cells

Mitosis

● There are 4 main sub phases (?)

● There are 4 main sub phases (PMAT)

○ Prophase

○ Metaphase

○ Anaphase

○ Telophase

Prophase:

Prophase:

• Chromosomes becomes visible as dense paired, chromatin attached at a centromere

• Centrosomes move to opposite poles

• Nuclear Membrane begins to breakdown

• Spindle fibers ‘strings’ of protein to pull chromatids apart

Metaphase: ?

Metaphase:

• Chromatin lines up in the middle of the cell at equatorial plate

(Think M for Middle → Metaphase)

• Spindle fibres attach to the centromere

• Prepare them nicely to cut the DNA in half!

Anaphase: ?

Anaphase:

• Centromeres split

• Sister Chromatides are separated from one another

• Chromatids move to opposite poles

Telophase:

Telophase:

• Like a reverse of prophase.

• Chromatids reach poles

• The dense chromatin undoes itself, into strings again

• Nuclear membrane reforms around each set of Chromatin (Now there are two nuclei)

Stage 3 cell cycle?

what?

Cytokinesis:

• Membrane pinches inward to make two separate cells.

• Division of Cytoplasm

• The dense chromatin undoes itself, into strings again

• The nucleus comes back surrounding the chromatin (Now there are two nuclei)

• Cell returns to interphase

Centromere: ?

Centromere:

• Structure that joins sister chromatids

• Chromatid: ?

Chromatid:

• Half of a duplicated chromosome