+

The Cell CycleInterphase, Mitosis & Cytokinesis

+Learning Objectives

+Define these KEYWORDS

Centromere Chromatin Chromatid Chromosome Histones Telomeres

+The Cell Cycle….

INTERPHASE – Gap 1 (G1), Synthesis (S) and Gap 2 (G2)

MITOSIS – Prophase, Anaphase, Metaphase, Telophase CYTOKINESIS

+INTERPHASE

Gap 1 (G1): - Cells grow in size and duplicate their organelles

- Cells carry out normal functions

Checkpoint

Synthesis (S) – DNA in the nucleus is replicated so there are now jjjjjjjjjjjjjjjjjjjjjjjj2 sets of DNA

Checkpoint

Gap 2 (G2) – Cells continue to grow so they are large enough to jjjjjjjjjjjjjjjjjjjj divide

+Checkpoints make sure the cells have enough nutrients, are the correct size and that the DNA is undamaged.

Once the cells have passed the checkpoints, they are ready for division.

By the end of interphase, each cell has 2 FULL SETS OF DNA – or chromosomes – and is large enough to divide.

+MITOSIS Divides the cell’s nucleus into 2 genetically identical

nuclei – each with its own full set of DNA

+ • Prophase

• Metaphase

• Anaphase

• Telophase

chromosomescentromere

centriole

Spindle fibers

Metaphase plate

Mitosis

+

Complete activity sheet.

Cut out the stages and put them in the correct order, matching them to their correct picture and description.

+INTERPHASE

+MITOSIS

+CYTOKINESIS

+CYTOKINESIS Divides the cytoplasm into 2 cells. Cytokinesis differs in animal and plant

cells.

In ANIMAL CELLS:

The membrane forms a furrow that is pulled inwards by tiny filament like a drawstring.

Gradually, the membrane pinches closed, forming a separate cell around each nucleus.

Cytoplasm is divided evenly between daughter cells

+CYTOKINESIS Divides the cytoplasm into 2 cells. Cytokinesis differs in animal and plant cells.

In PLANT CELLS:

The membrane cannot pinch inward because of the cell wall so a cell plate is formed between the 2 nuclei.

Golgi apparatus supplies the new plasma membrane.

A new cell wall grows and cytoplasm is divided evenly between daughter cells.