Plant and animal cells I Today’s objectives are: Year 7 Science – 6th of March 2013 – Cell Unit. S. Rathier To practice the skills you have learned last week To discover what animal and plant cells look like under the microscope and learn how we can tell them apart To learn how to make biological drawings

Starter – cell fact or fiction? There are about cells in your body

The heaviest known cell is the ostrich egg

There are more bacterial cells in your body than human cells

Brain cells live longer than any other cell

Some cells eat other cells

The longest cell in your body is over a meter long

People and mushrooms have the same type of cells

Cells glow in the dark

Cells commit suicide

What are cells?

Cells are the building blocks of life The cell is the smallest viable form of life.

Using microscopes – quick reminder Carry with both hands close to body Bring the stage up looking from the side Start at low power (red lens)

Prepare your own animal and plant cell slides! Watch this video closely: it’s all in there!

Biological drawings Basic rules 1)Use whole page 2)Titles 3)Use pencil 4)Use solid lines 5)Don’t colour or shade 6)Give magnification Title Draw 1 onion cell and 1 cheek cell – they will be collected at the end and you will need them next lesson, so do your best work! Title For example 10 ×10 = 100 or ×100 magnification’

Biological drawings Criteria for a good drawingMarksMy score Underlined title1 Magnification calculated and shown2 Drawing fills most of page1 Sharp pencil used1 Solid lines1 Any shading is done with dots1 Cell parts are labelled2 Label lines are drawn with ruler1 TOTAL10

Activity – plant and animal cells 1. Plant cell – DO THIS BEFORE YOU TRY THE CHEEK CELL Work in pairs, prepare 1 slide for both Person 1 get the microscope, the marking scheme for drawings and the blank paper (2 sheets per pair) Person 2 get the onion, tweezers, 1 slide, 1 cover slip and dye (iodine) Each student to draw 1 plant cell on the upper half of the sheet of paper Drawing of a plant cell

2. Animal cell – LISTEN CAREFULLY TO SAFETY INSTRUCTIONS Method Scrape the cells out of your mouth with a cotton bud using your finger to push against the cotton bud. Put the cells on the slide by gently rubbing the cotton bud against the slide ( Caution : Do not let the slide touch the desk as this will ruin your results). Add 1 DROP of Methylene Blue Stain to the slide (Do this over a sink as it can get messy!). Put a coverslip over the slide ( Caution : Be careful with the coverslip as they are very delicate and break extremely easily). Put the slide under the microscope. Focus the microscope on the 10x objective, then the 20x and 40x objectives. USE OWN COTTON SWAB ONLY ONCE DIPOSE OF AS INSTRUCTED IMMEDIATELY

Activity – plant and animal cells 2. Animal cell – LISTEN CAREFULLY TO SAFETY INSTRUCTIONS Work in pairs, prepare 1 slide each Person 1 get 2 cotton swabs, 2 slides, 2 cover slips, dye (methylene blue) Person 2 get the blank paper (2 sheets per pair) Each draw 1 cheek cell on the lower half of the paper. You must finish this work today so you may not get to draw your own cell! Diagram of an animal cell

From what you have learned today…. Use mini whiteboards Which of these are plant and which of these are animal cells?

Extension work The two types of cells (plant and animal) we have been observing today have some features in common. Which might these be? What are some of the differences you have noticed?

Definitions Cell membrane: contains the cell and controls what passes in and out of the cell Nucleus: controls the cell and contains instructions to make more cells Cytoplasm: where the chemical reactions take place to keep the cell alive and working Cell wall: support the cell Vacuole containing cell sap (no chloroplasts in onion cells)