Chapter 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) PartFunction Cell Membrane Cytoplasm Nucleus Chloroplast Cell Wall Vacuole

PartFunction Cell MembraneProtects the cell Controls what enters & leavest the cell CytoplasmPlace where chemical reactions take place NucleusControls the cells activities ChloroplastCarries out photosynthesis Cell WallGives shape to the cell VacuoleStores 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 CellsAnimal Cells Cell wall present No chloroplasts Large vacuoles

Plant CellsAnimal Cells Cell wall presentNo cell wall Chloroplasts presentNo chloroplasts Large vacuolesSmall 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: PartFunction 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 2 CELLS 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 2 CELLS AND THE MICROSCOPE

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 2 CELLS AND THE MICROSCOPE

Draw a few drops of iodine solution across the cells using absorbent paper. CHAPTER 2 CELLS AND THE MICROSCOPE

Definitions Tissues A tissue is a group of similar cells with the same function e.g. muscle tissue Organ An organ is made of many different tissues working together e.g. the heart Systems A system is a group of organs working together e.g. the circulatory system

PlantsAnimals TissueStorage tissue OrganFlower SystemShoot System Quiz