CELL CYCLECell Division

cancer

https://science.education.nih.gov/supplements/nih1/cancer/activities/activity2_animations.htm

Strawberry Division!

Why do cells need to divide? Growth – so organisms can increase in

size (natural selection theory) Development – for cells to become

specialized (e.g. create organs) Repair – for cells to replace removed or

dead cells (e.g skin cells)

Which cells divide the most? Skin cells are dividing all day, everyday. We lose around 30,000 to 40,000 skin cells a

minute! That’s 50 million skin cells lost in one day!

Cell Cycle – Somatic Cells

Interphase – cell growth takes placeInter = enter

Mitosis – division of DNA(chromosomes)mito = strong, powerfulsis = process

Cytokinesis – division of cytoplasm cyto = cell

kinesis = movement

What is the 1st part of the cell cycle?

Interphase G1 (growth stage one) : cell is

growing & developing and making proteins

S (synthesis): DNA replication process

G2 (growth stage two): cell is making final preparations for cell division

Cell Cycle

Closer look at “S phase”

What is the 2nd part of the cell cycle?

MitosisProphaseMetaphaseAnaphaseTelophase/Cytokinesis

Mitosis

Prophase-chromatin begins to coil into think, visible chromosomes

Mitosis

Metaphase-spindles fibers line up chromosomes in the “middle”

Mitosis

Anaphase-spindle fibers move chromosomes “apart”

Mitosis

Telophase-chromosomes reach opposite ends-centromere

Cytokinesis

Animal Cell Plant Cell

Cytokinesis: Which cell is pictured?

What happens if the cycle is disrupted?

Cancer is uncontrolled cell division or inappropriate cell proliferation

Cascade of chemical reactions that relay a cell from one stage to the next

Set of checkpoints that monitor completion of critical events and delay progression to thenext stage, if necessary

Genetic alterations shown to contribute to cancer development

Gain-of-function mutations (oncogenes) Loss of function mutations (“tumor suppressor” genes)

Independent Activity

In ten minutes, you will be able to write 6 sentences using the following words:

Interphase Prophase Metaphase Anaphase Telophase Cytokinesis