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IntroductionIntroduction Cells are the basic units of organisms

Cells can only be observed under microscope Two basic types of cells:

Animal Cell Plant Cell

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Plant CellPlant Cell

Made of cellulosewhich forms very thinfibres

Strong and rigid In plant cells only

Cell wall

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Protect and supportthe enclosedsubstances(protoplasm)

Resist entry of excesswater into the cell

Give shape to the cell

Cell wall Plant CellPlant Cell

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A dead layer

Large empty spacespresent between

cellulose fibres

@ freely permeable

Cell wall Plant CellPlant Cell

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Lies immediatelyagainst the cell wall

Made of protein andlipid @ Selectivelypermeable

Cell membranePlant CellPlant Cell

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A living layer Can control the

movement of

materials into andout of the cell

Cell membranePlant CellPlant Cell

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Jelly-like substanceenclosed by cellmembrane

Provide a medium forchemical reactions totake place

Cytoplasm Plant CellPlant Cell

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Contains organellesand granules :e.g. chloroplaste.g. mitochondrion

CytoplasmPlant CellPlant Cell

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OrganellesOrganellesvery small size can only be

observed under electronmicroscope

has specific functions

in cytoplasm

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Contain the greenpigment chlorophyll

To trap light energy,to make food byphotosynthesis

Plant CellPlant Cell Chloroplast

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Contain starch grains(products of

photosynthesis)

ChloroplastPlant CellPlant Cell

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Rod shape For respiration

Plant CellPlant Cell Mitochondrion

( mitochondria )

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Active cells ( eg.sperms, liver cells)have moremitochondria

Plant CellPlant Cell Mitochondrion( mitochondria )

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Starch granules Oil droplets

Crystals of insolublewastes

Plant CellPlant Cell Non-living

granules

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large central vacuole Surrounded by tonoplast Contains cell sap

a solution of chemicals(sugars, proteins,mineral salts, wastes,pigments)

Plant CellPlant Cell Vacuole

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Control the normalactivities of the cell

Bounded by anuclear membrane

Contains thread-like chromosomes

Plant Cell

Nucleus

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Each cell has fixednumber of chromosomes Chromosomes carry

genes

genes control cell characteristics

Nucleus

Plant CellPlant Cell

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Different kinds of plant cellsDifferent kinds of plant cells

Onion Epidermal Cells

Root Hair Cell

root hair

Guard Cells

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mitochondrion

nucleus

glycogen

granule

cellmembrane

cytoplasm

Animal cellAnimal cell

No cell wall andchloroplast

Stores glycogengranules and oildroplets in thecytoplasm

vacuole

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Different kinds of animal cellsDifferent kinds of animal cells

white blood cell

red blood cell

cheek cellssperm

nerve cell

muscle cell

Amoeba

Paramecium

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Similarities between plant cellsSimilarities between plant cellsand animal cellsand animal cells

Both have a cell membrane surroundingthe cytoplasm

Both have a nucleus

Both contain mitochondria

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Differences between plant cellsDifferences between plant cellsand animal cellsand animal cells

Animal cells Plant cellsRelatively smaller in

size

Irregular shape

No cell wall

Relatively larger insize

Regular shape

Cell wall present

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Animal cells Plant cellsVacuole small or absent

Glycogen granules asfood store

Nucleus at the centre

Large central vacuole

Starch granules asfood store

Nucleus near cell wall

Differences between plant cellsDifferences between plant cellsand animal cellsand animal cells

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The cell as the basic unit of lifeThe cell as the basic unit of life Cell is the smallest unit of living organisms Unicellular organisms are made of one cell

only

The cells of multicellular organisms arespecialized to perform different functions e.g. mesophyll cells for photosynthesis

and root hair cells for water absorption

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Levels of organizationLevels of organization

Cells are grouped together and work as a whole to perform special

functions

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TissueTissue

A group of similar cells to perform aparticular function Animals : epithelial tissue, muscular

tissue Plants : vascular tissue, mesophyll

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OrganOrganDifferent tissues group together tocarry out specialized functions Heart : consists of muscles,

nervous tissue and blood vessels

Leaf : consists of epidermis,mesophyll and vascular tissue

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Stoma

Air Space

Spongy MesophyllCell

ChloroplastThe Structures of a Leaf Palisade

Mesophyll Cell

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The Structures of a Heart

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SystemSystem Several organs and tissues work together

to carry out a particular set of functions in aco-ordinated way

Human : digestive, respiratory, excretory,circulatory and reproductive systems

Plant : root and shoot systems

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System in our bodySystem in our body examples of systems :

Digestive SystemRespiratory SystemCirculatory SystemNervous SystemReproductive System

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The Respiratory System

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The Circulatory System

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The Nervous System

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Male Reproductive System

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Female Reproductive System

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Level of OrganizationLevel of Organizationcells (e.g. muscle cells, nerve

cells)tissues (e.g. muscle, epithelium)organs (e.g. heart, lungs, stomach)systems (e.g. circulatory system)organisms (e.g. man)

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Its You

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