Unit 2: Mitosis and Cell division

Mitosis definition

When a cell divides to produce two genetically identical diploid daughter cells.

Interphase

(not part of mitosis, but part of cell cycle)

• DNA is replicated

• cell grows in size

• increase in sub-cellular structures (mitochondria)

Prophase

• DNA condenses into chromosomes

• chromosomes become visible

• nuclear membrane breaks down

metaphase

• spindle fibres attach to chromatids

• chromosomes align at the equator of the cell

anaphase

• Spindle fibres pull chromatids to opposite poles of the cell

telophase (cytokinesis)

• chromosomes reach the poles of the cell

• nuclear membrane reforms (around each pole)

• cytokinesis = splitting of the cell (cytoplasm + cell membrane split)

Uses of mitosis

• Growth

• Replacement of cells

• Asexual reproduction

Mnemonic for mitosis

I - interphase

Possess - prophase

More - metaphase

Alligators - anaphase

Than - telophase

Charles - cytokinesis

Define cell growth

• increase in organelles, size, mass/volume and cells

Cell division

Divides into two genetically identical diploid daughter cells (animals+plants)

Cell differentiation

• When a cell becomes specialised into a specialised cell (animals+plants)

Plant elongation

Increase in length of cell to help plants face sun or reach water in roots.

Growth in animals compared to growth in plants

• Plants grow continuously

• Animals grow at faster rates at younger ages

How do plants grows

• Division

• differentiation

• elongation

How animal cells grow

Division and differentiation

Tumour

mass of cells caused by uncontrolled division

What can cause a tumour

A mutation in a gene that can cause rapid, uncontrolled division

When does a tumour turn into cancer

When tumour starts to invade surrounding tissue

metastasising

If tumour spreads from one part of the body to the other