Objectives: To be able to: describe how cells divide for growth and reproduction OUTCOMES: MUST be able to state how multiply in number by growing and dividing SHOULD be able to describe how cells divide differently for different types of reproduction COULD be able to describe how specialised cells fuse during fertilisation in plants

To be able to:

describe how cells divide for growth and reproduction

OUTCOMES:

MUST be able to state how multiply in number by growing and dividing

SHOULD be able to describe how cells divide differently for different types of reproduction

COULD be able to describe how specialised cells fuse during fertilisation in plants

Where do cells come from? Think of the following situations….. REPAIR... You cut your finger. The wound is eventually healed and weeks later you can’t even see where the cut used to be. REPRODUCTION... Your body can make sex cells. In humans, these cells are the sperm and egg. These cells contain the same genetic information that can be found in other body cells. GROWTH... Your body loses cells and cells are constantly dying. However, your skin never disappears and you don’t get smaller. This is because you are constantly producing new cells and these new cells are produced from your existing cells.

REPAIR REPRODUCTION GROWTH You will have seen that our bodies produce cells for three main reasons: New cells are produced from old cells dividing. Where do cells come from?

REPAIR

REPRODUCTION

GROWTH

Cell division animation Cell Division Movie

Cell division animation

Cell Division Movie

Q. Can you think of a problem if one cell splits to produce two cells? A. The two new cells would be smaller than the original cell. Therefore, a cell needs to make new copies of the material inside itself as well as the membrane and nucleus. Just before a cell divides, it will appear to grow slightly as it reproduces everything inside itself. The nucleus must also divide into two equal halves. This only occurs once the nucleus has doubled from its original size. Where do cells come from?

Cell division occurs extremely quickly and can happen over and over again. Grow quickly This is how it is possible for the body to ... Repair cuts and replace dead cells quickly. Produce an enormous number of reproductive cells. Where do cells come from?

Cell Division

Cell growth Animal cells: Plant cells:

Plant reproduction For a plant to reproduce two stages must happen: Stage 1: Pollination – pollen from one plant is taken to another by insects or the wind:

Pollination animation

Pollination animation

Plant reproduction Stage 2: Fertilisation – a pollen tube grows down through the style and the pollen grain (which contains the male sex cell) travels down the tube to fertilise the female egg cell: Ovaries

Pollination & Fertilization

IT: Label The Diagram