The Cell Cycle

How long do the cells in your body live? Question How long do the cells in your body live?

Answer It depends.

Answer Different cells live for different lengths of time. For example, here’s how often some different kinds of cell need to be replaced.

Answer Skins cells – 20 days Liver cells – 200 days Brain cells – 30 – 50 years Intestinal lining – 3 days Stomach lining – 2 days Red blood cells – 120 days

If cells have such a short life-span, and you are made of 100 000 000 000 000 cells, this must mean that A LOT of cells are dying all the time.

If cells have such a short life-span, and you are made of 100 000 000 000 000 cells, this must mean that A LOT of cells are dying all the time. In fact, about 300 million of your cells die each minute.

This must also mean that A LOT of cells are being produced to replace the ones that are lost.

Cells are produced as part of THE CELL CYCLE

The Cell Cycle So, how do we replace all those cells that we lose everyday?

The Cell Cycle So, how do we replace all those cells that we lose everyday? Cell Division

The Cell Cycle Most of the cells in your body replace themselves in a process called MITOSIS

The Cell Cycle The cell cycle is divided into three stages

The Cell Cycle Interphase Mitosis Cytokinesis The cell cycle is divided into three stages Interphase Mitosis Cytokinesis

The Cell Cycle Interphase is the longest stage in the cells life. It is when a cell carries out its various functions within the organism. During interphase cells Grow in size Prepare for cell division Replicate their DNA

DNA Replication DNA makes a copy or “replica” of itself during interphase. So for a little while the cell has 2 complete sets of DNA.

DNA Replication

Mitosis Mitosis is the next stage in the cell cycle. (But a lot of things happen.) Mitosis is divided into 4 phases. Prophase Metaphase Anaphase Telophase

Mitosis

The Cell Cycle The last stage of the cell cycle is Cytokinesis. This is when the original (parent) cell separates into to new (daughter) cells

The Cell Cycle - Review A single cell divides to make two new cells – this is how our body replaces cells. Most of the cells in our body do this with a process called MITOSIS.

The Cell Cycle - Review Before mitosis can occur the DNA in the cell must Replicate. This happens during Interphase. Mitosis results in two new cells that are IDENTICAL to the original parent cell.