BiologyBiology

CELLCELL

The basic unit of The basic unit of structure and function structure and function in living organisms.in living organisms.

Extremely smallExtremely small can be seen properly can be seen properly

only when magnified only when magnified and viewed through and viewed through microscope.microscope.

CELLCELL

Your body has about Your body has about 50 billion cells; some 50 billion cells; some microscopic microscopic organisms only have organisms only have one cell, e.g. amoeba.one cell, e.g. amoeba.

The structure of a typical plant cellThe structure of a typical plant cell

cell wall

cell membrane

vacuolecytoplasm

nucleus

chloroplast

Non-living granules

Cell WallCell Wall

Found in Found in plant cellsplant cells only. only. Made of cellulose fibre.Made of cellulose fibre. Freely permeable.Freely permeable.

Functions : Functions :

a/ To protect and support the enclosed protoplasm.a/ To protect and support the enclosed protoplasm.

b/ To resist the entry of excess water into the cell.b/ To resist the entry of excess water into the cell.

Cell membrane / Plasma membraneCell membrane / Plasma membrane

All cells are surrounded by cell membrane.All cells are surrounded by cell membrane. It is very thin.It is very thin. It is selectively permeable.It is selectively permeable.

Function:Function:

To control the passage of materials in and out of To control the passage of materials in and out of the cellthe cell..

CytoplasmCytoplasm

A clear, jelly like substance enclosed by the cell A clear, jelly like substance enclosed by the cell membrane.membrane.

It consists of an aqueous solution with proteins.It consists of an aqueous solution with proteins.

Function:Function:

a/ A medium for chemical reactions to take place.a/ A medium for chemical reactions to take place.

b/ To hold the organelles and granules.b/ To hold the organelles and granules.

OrganellesOrganellesChloroplastsChloroplasts

Present in green plant Present in green plant cells cells

Contains the green Contains the green pigment chlorophyllpigment chlorophyll

Function:Function:

The site of The site of photosynthesis.photosynthesis.

OrganellesOrganellesMitochondriaMitochondria

Present in all living cells.Present in all living cells. Appear as rod-shaped or Appear as rod-shaped or

cylindrical organelles.cylindrical organelles. Cellular respiration takes Cellular respiration takes

place there and food is place there and food is oxidized to release energy.oxidized to release energy.

Also known as the ‘Power Also known as the ‘Power House’.House’.

Function:Function: Site of respiration.Site of respiration.

GranulesGranules

Crystals of insoluble Crystals of insoluble waste.waste.

Starch granules in the Starch granules in the cytoplasm as food cytoplasm as food reserve in plant cells.reserve in plant cells.

VacuoleVacuole

Fluid-filled cavities Fluid-filled cavities bounded by a membrane bounded by a membrane called called tonoplasttonoplast..

Contains a solution of Contains a solution of sugars, protein and mineral sugars, protein and mineral salts called salts called cell sapcell sap..

The vacuoles of animal The vacuoles of animal cells are usually very small.cells are usually very small.

vacuole

NucleusNucleus

Contains genes (carry Contains genes (carry the genetic information).the genetic information).

Genes are made up of Genes are made up of DNA and they are DNA and they are located on the located on the chromatin/chromosomeschromatin/chromosomes..

NucleusNucleus

Function:Function:

a/ controls the activities a/ controls the activities

of the cell.of the cell.

b/ transmits genetic b/ transmits genetic

information to the information to the

next generation.next generation.

Basic structure of animal cellBasic structure of animal cell

mitochondrion

nucleusnucleolus

nuclear membrane

cytoplasm

vacuole

cell membrane

Animal CellsAnimal Cells

Animal cells do not have Animal cells do not have cell wall and chloroplast.cell wall and chloroplast.

The vacuole in animal cells The vacuole in animal cells are usually small.are usually small.

Non-living granules are Non-living granules are usually glycogen or oil usually glycogen or oil droplets.droplets.

There is a greater variety of There is a greater variety of animal cells than the plant animal cells than the plant cells.cells.

Similarities between animal and Similarities between animal and plant cellsplant cells

Both have:Both have:

nucleusnucleus cytoplasmcytoplasm

mitochondrionmitochondrion chloroplastchloroplast

cell wallcell wall cell membranecell membrane

Differences in Animal and Differences in Animal and Plant CellsPlant Cells

Plant Cell Animal Cell With cell wall Without cell wall With chloroplast Without chloroplast Large vacuole at the central

Vacuoles are small or absent

Starch granules as food reserve

Glycogen granules as food reserve

Usually larger in size and regular in shape

Usually smaller in size and irregular in shape

Nucleus found just beneath the cell wall

Nucleus found in the center of the cell

Can you distinguishCan you distinguish plant cells and animal cells from plant cells and animal cells from

the following pictures?the following pictures?

Plant cells Animal cells

Can you distinguishCan you distinguish plant cells and animal cells from plant cells and animal cells from

the following pictures?the following pictures?

Animal cells Plant cells

WEBWEB SITESSITES

http://library.thinkquest.org/3564/

http://www.kapili.com/biology4kids/cell

http://personal.tmlp.com/Jimr57/tour/cell/