The area where protein synthesis takes place. All proteins needed in cells are made here.

Organelles that release most of the cells energy during respiration.

The site where chemical reactions occur. Respiration occurs here- oxygen + sugar react to release energy the cell needs.

Controls the functions and activities of a cell. Contains the instructions for making new cells or new organisms.

Made of cellulose for strength and support.

Found in the green area of plants and help plants to undergo photosynthesis.

Controls passage of substances in and out of the cell.

A space in the cytoplasm filled with sap which is important for keeping cells rigid to support the plant.

The Big Questions

• How do we even know cells are even there?

• What has advanced our understanding of cells?

Cells and Microscopy

Specification Link

• Describe how plant and animal cells can be studied in greater detail with a light microscope

• Demonstrate an understanding of how changes in microscope technology have enabled us to see cells with more clarity and detail than in the past, including simple magnification calculations

Light Microscopes

• Microscopes let us see things that we can’t see with the naked eye.

• Light microscopes were invented in the 1950’s. They let us see things like nuclei, chloroplasts and mitochondria.

Microscopes

Light Microscopes

• Invented in 1590’s.

• They let use see things like nuclei, chloroplasts and mitochondria.

Electron Microscopes

• Invented in the 1930’s.

• Let use see much smaller things in more detail like the internal structure of mitochondria and chloroplasts.

Magnification • The length of the magnified object = Length of the object X Magnification

• Rearranging this tells us that

Length of object = Length of the magnified objectThe magnification

1. A scientist looks at a cell with a microscope that has a magnification of times 40.

The cell is 0.1 mm long.Calculate the size of the magnified image.(2)

2. The electron microscope can magnify images...........................................................................than the light microscope.

(ii)  The diagram shows a sperm cell that has been magnified 100 000 times.

  Calculate the actual length of the sperm cell.

Starter

• Using the magnification calculations you have been given, devise a exam question for your partner to answer.

• 5 Minutes to create one• 5 Minutes for your partner to try and

answer it.• You must then mark it.

Using Microscopes

Eyepiece Lens

Objective Lens

Mirror

StageFocusing

Knob

Handle

PARTS OF A MICROSCOPE

Test

Making an onion skin

slide

Step 1

• Using some forceps or your fingernails, peel off the inside layer of a piece of onion.

Step 2

• Place your onion skin onto a glass microscope slide. Be careful that you don’t fold the skin.

Step 3

• Place one or two drops of iodine onto the onion skin. This will help to stain the specimen, making it easier to see the cells. 

Step 4

• Carefully lower a coverslip onto your onion skin. If you do this carefully and slowly you will not get air bubbles.

Step 5

• Now take your slide to a microscope and have a look. Try looking at the cells using the different objective lenses.

• Try to make a simple drawing of the cells you can see.

What can go wrong

air bubbles

onion skin folded over

image of onion skin as viewed under microscope

very detailed drawing of image

simple drawing illustrating main features

X 4 objective

X 10 objective

X 40 objective

Onion Skin 

How to Label Drawings

cell membrane

cytoplasm

nucleus

2.  Use straight lines, with NO ARROWS

1.  clear, simple drawing of main features

3.  label main features

 4.  indicate total magnification used Magnification x 100

Your Tasks

• Write a brief method about what you are going to do from the notes you have made.

• You are then required to draw 3 drawings in PENCIL at the 3 different magnifications.

• Try to label your diagrams.• Remember you are not going to see

every organelle!

I.S

• The discovery of DNA was a major breakthrough in science. Your Task is to find out what was the role of Rosalind Franklin in the discover of DNA.