Chapter 3: The CellChapter 3: The Cell

What do you know about cells?

Objectives:

1. To define the term cells

2. To look at the basic structure of the cell

3. To identify the main parts of the cell

4. To distinguish between plant and animal cells

5. To identify the main parts of a microscope

6. To use a light microscope to examine plant and animal cells under low and high power

All living things are made of cells.

Cell Structure

Cells are made up of 3 main parts:

1. Cell Membrane

2. Cytoplasm

3. Nucleus

Structure of Animal & Plant Cell

Parts of the cell and their function (job)

Part Function

Cell Membrane

Cytoplasm

Nucleus

Chloroplast

Cell Wall

Vacuole

Part Function

Cell Membrane Protects the cell

Controls what enters & leavest the cell

Cytoplasm Place where chemical reactions take place

Nucleus Controls the cells activities

Chloroplast Carries out photosynthesis

Cell Wall Gives shape to the cell

Vacuole Stores materials in the cell

Parts & Functions of the Cell

Plant cells have all the features present in animal cells.

In addition, they have:– A cell wall for

strength– Chloroplasts– Large vacuoles

Differences between Plant & Animal Cells

Plant Cells Animal Cells

Cell wall present

No chloroplasts

Large vacuoles

Plant Cells Animal Cells

Cell wall present No cell wall

Chloroplasts present No chloroplasts

Large vacuoles Small vacuoles or no vacuoles

Differences between plant & Animal Cells

Is this a plant cell or an animal cell?

Give 2 reasons for your answer

Identify the main parts of the plant cell

A

B

D

C

E

E

A microscope is used to view small objects in detail.

Identify the main parts of the microscope

A

B

C

D

E

The parts of a microscope and their functions are as follows:

Part Function

Eye piece lens

Objective lens

Coarse Focus Wheel

Fine Focus Wheel

Stage

Mirror or light source

Magnification using a light microscope

• The total magnification is calculated by multiplying the power of the eyepiece by the power of the objective lens being used.

Total magnification = eye piece lens X objective lens

• To examine animal or plant cells under a microscope:– Make sure there is light passing through the

opening in the stage.– Use the lowest power lens on the nosepiece.– Clip the slide onto the stage.– Turn the coarse focus knob to bring the stage

close to the slide.

CHAPTER 2CELLS AND THE

MICROSCOPE

– Turn the coarse focus knob to bring the lens away from the slide.

– Move the slide so that the cells of interest are in the centre.

– Adjust the amount of light passing through the slide.

– Change the objective lens to a higher power and re-focus using the fine focus knob.

– Draw labelled diagrams of the cells at each magnification.

CHAPTER 2CELLS AND THE

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• To prepare a slide from plant tissue:– Cut an onion and remove

a thin layer of cells.– Place the onion cells in

water on a microscope slide.

– Place a cover slip over the onion cells.

Mandatory Experiment To prepare a slide from plant tissue and draw a diagram of the cells under magnification

CHAPTER 2CELLS AND THE

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• Draw a few drops of iodine solution across the cells using absorbent paper.

CHAPTER 2CELLS AND THE

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Definitions

TissuesA tissue is a group of similar cells with the

same function e.g. muscle tissue OrganAn organ is made of many different tissues

working together e.g. the heartSystemsA system is a group of organs working

together e.g. the circulatory system

Plants Animals

Tissue Storage tissue

Organ Flower

System Shoot System

Quiz