Cells Lesson 2

Starter A reminder about microscopes from lesson 1? Click ↑ (2 mins) They all make things look bigger! Explain to pupils that these things all make things look bigger than with the naked eye 2

Learning outcomes By the end of this lesson: All pupils can: use a microscope safely and successfully make a drawing and peer assess using success criteria Name the basic parts of a cell Most pupils can: recall functions of each part describe the differences between a cell, tissue, organ and system can calculate magnification Some pupils can explain ‘cell theory’

What is the difference between these two groups? Then ask – “Why do we call some living and some non-living?” 4

Movement Reproduction Sensitivity Growth Respiration Excretion Nutrition

Movement Reproduction Sensitivity Growth Respiration Excretion Nutrition Living things do all of these. Non-living things do not.

What are living things made from? All living things are made from cells. Cells are the building blocks for every living organism – even me and you! This is called cell theory. As cells are very small, we can only see them with the help of a microscope.

Festuca glauca [flower] Plants – grasses magnification x10 Festuca glauca [leaf] Festuca glauca [flower]

Festuca glauca [flower] Plants – grasses magnification x60 Festuca glauca [leaf] Festuca glauca [flower]

Plants – magnification x10 Bottom Top Pansy [flower] Golden hop [leaf]

Plants – magnification x60 Kerria japonica [top] Golden hop

Plant tissue – magnification x60 Crassulacean leaf [ts] x60 Dicotyledonous root [ts] x60

Plant tissue – magnification x200 Crassulacean leaf [ts] x200 Dicotyledonous root [ts] x200

Animal tissues – magnification x10 Entire eye x 10 [an organ] Cerebellum [brain] x 10

Animal tissues – magnification x60 top back front Entire eye x60 Cerebellum [brain] x60

Animal tissues – magnification x200 Cerebellum [brain] x200

Responsible use of microscopes Microscopes are fragile and delicate: They should always be carried with two hands: one underneath and one holding the curved part of the body. You should not touch the lenses. Persistent mistakes include: holding the microscope with one hand focussing down onto the slide and breaking it turning the objective lens around and crashing into the slide forgetting to mop up excess liquid.

How to use a microscope Now follow the instructions below carefully. Make sure you have selected the low power objective lens (it’s the smallest). Look down the eyepiece and adjust the mirror until it is as light as you can get it. Move the focussing knob until the objective lens is as far down as it will go. Put your slide on the stage and secure it with the stage clips. Using the focussing knob, move the objective lens slowly up. Until you can see something. (You will need to keep looking down the eyepiece as you do this). When you think you can see something, check with the teacher before drawing what you see. When you have finished, remember to remove the slide from the microscope before packing it away.

Rules for microscope drawing: Write a clear heading. Use a sharp HB pencil. Draw firm, continuous lines and avoid using too much shading. Include the magnification (see next slide as to how to do this) Draw label lines with a ruler. These must not touch the structure they are labelling and should not cross each other. Write labels horizontally on the page and arrange them neatly around the drawing.

List the mistakes in diagram b

Microscopes, magnification and scale On the next slide are photographs of a ruler at different magnifications. This will help you work out the size of the objects on other slides.

Magnification Magnification x60 Intervals in mm Magnification x10 Interval is 1 mm

magnification of OBJECTIVE lens x magnification of EYEPIECE lens Calculate the total magnification and write it on your drawing: Look at this short video clip: http://www.youtube.com/watch?v=NatMpe5iYtE – 1 min 55 s; cell structure and function Total magnification = magnification of OBJECTIVE lens x magnification of EYEPIECE lens

Label the parts of the animal cell 24

Label the parts of the animal cell Nucleus Cell Membrane Cytoplasm 25

The cell – a living factory!

What does each part do?

Label the parts of a typical plant cell 28

Label the parts of a typical plant cell Cell Membrane Vacuole Cell Wall Nucleus Chloroplast Cytoplasm 29

Peer assessment Write a clear heading. Use a sharp HB pencil. Draw firm, continuous lines and avoid using too much shading. Include the magnification. Draw label lines with a ruler. These must not touch the structure they are labelling and should not cross each other. Write labels horizontally on the page and arrange them neatly around the drawing.

Functions of the cell parts extra information on this link: http://www Cell wall Cell membrane Vacuole Nucleus Cytoplasm Chloroplasts Maintains shape of cell Allows substances to enter and leave the cell. Contains cell sap and water Controls what happens in the cell. Is the site of cell reactions Contains green chlorophyll for making food 31

Two songs/rap that may help you remember in the future: http://www Two songs/rap that may help you remember in the future: http://www.youtube.com/watch?v=RSTB57a6Uzk&feature=related – 2 mins 11 s; cell song http://www.youtube.com/watch?v=Yu21ShnKhHk&feature=related – 1 min 23 s; plant and animal cell rap

From cells to systems This activity introduces some key ideas about the building blocks of life. We will revisit some of the ideas in future lessons. Click on the link: http://www.bbc.co.uk/schools/ks3bitesize/science/organisms_behaviour_health/cells_systems/activity.shtml

Extension videos http://www.youtube.com/watch?v=rABKB5aS2Zg&feature=related advanced animation of structure and function of the cell (first 3 mins) http://www.youtube.com/watch?v=zufaN_aetZI 17 mins 12 s; evolution of the eukaryotic cell