3the Basic Structures of a

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CECIRLY G. PUIG

Asst. Professor IUniversity of Southeastern PhilippinesTagum-Mabini Campus

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Introduction 

• 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 Cell

 – 

Made of cellulose which forms very thin

fibres 

 – Strong and rigid 

 – In plant cells only 

• Cell wall 

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 –  Protect and support

the enclosedsubstances

(protoplasm) 

 –  Resist entry of excess water into the cell

 –  Give shape to the cell 

• Cell wall 

Plant Cell

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 –  A dead layer 

 – Large empty spaces

present between

cellulose fibres

freely permeable 

• Cell wall 

Plant Cell

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 – Lies immediatelyagainst the cell wall 

 – Made of protein and

lipid Selectivelypermeable

• Cell membrane

Plant Cell

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 – 

 A living layer  – Can control the

movement of

materials into andout of the cell

• Cell membrane

Plant Cell

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 – Jelly-like substance

enclosed by cellmembrane 

 – Provide a medium for

chemical reactions to

take place 

• Cytoplasm

Plant Cell

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 – Contains organellesand granules : 

•e.g. chloroplast 

•e.g. mitochondrion 

• Cytoplasm

Plant Cell

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Organelles  very small size  – can only be

observed under electron

microscope 

has specific functions 

in cytoplasm 

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 – Contain the greenpigment chlorophyll 

•To trap light energy,

to make food by

photosynthesis 

Plant Cell• Chloroplast

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 – Contain starch grains

(products of

photosynthesis)

• ChloroplastPlant Cell

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 – Rod shape

 – For respiration 

Plant Cell• Mitochondrion

( mitochondria )

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 –  Active cells ( eg.sperms, liver cells)

have more

mitochondria

Plant Cell• Mitochondrion

( mitochondria )

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 – Starch granules

 – Oil droplets 

 – Crystals of insoluble wastes 

Plant 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 Cell•  Vacuole

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 – Control the normal

activities of the cell 

 – Bounded by a

nuclear membrane 

 – 

Contains thread-like chromosomes 

Plant Cell

•

Nucleus

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 – Each cell has fixed

number of chromosomes 

• Chromosomes carry 

genes 

 – 

genes control cell characteristics 

•

Nucleus

Plant Cell

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Different kinds of plant cells

Onion Epidermal Cells 

Root Hair Cell

root hair

Guard Cells

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mitochondrion

nucleus

glycogen

granule

cell

membrane

cytoplasm

 Animal cell

•No cell wall andchloroplast

• Stores glycogen

granules and oildroplets in the

cytoplasm

 vacuole

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Different 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 cells

and animal cells

Both have a cell membrane surroundingthe cytoplasm 

Both have a nucleus

Both contain mitochondria 

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Differences between plant cellsand animal cells

 Animal cells Plant cellsRelatively smaller in

size 

Irregular shape

No cell wall

Relatively larger in

size 

Regular shape

Cell wall present 

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 Animal cells Plant cells Vacuole small or absent 

Glycogen granules as

food store

Nucleus at the centre 

Large central vacuole 

Starch granules as

food store

Nucleus near cell wall 

Differences between plant cellsand animal cells

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Microscope

• Instrument for

observing small

objects

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Different parts of amicroscope

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Eyepiece

Fine adjustment

 Arm

StageCondenser

control knob

Base

Body tube

Course

adjustment

Iris diaphragm

Revolvingnosepiece

Objective

Clip

Condenser

Mirror

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The cell as the basic unit of life• Cell is the smallest unit of living organisms 

• Unicellular organisms are made of one cellonly

• The cells of multicellular organisms are

specialized to perform different functions  – e.g. mesophyll cells for photosynthesis

and root hair cells for water absorption 

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Levels of organization

• Cells are grouped together and work 

as a whole to perform special

functions

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Tissue

•  A group of similar cells to perform a

particular function  –  Animals : epithelial tissue, muscular

tissue

 – Plants :  vascular tissue, mesophyll

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Organ• Different tissues group together to

carry 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 Mesophyll

Cell

Chloroplast

The Structures of a Leaf 

Palisade

Mesophyll Cell

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The Structures of a Heart

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System

•Several organs and tissues work togetherto carry out a particular set of functions in a

co-ordinated way 

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

 – Plant : root and shoot systems

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System in our body• examples of systems : 

Digestive System 

Respiratory System 

Circulatory System 

Nervous System 

Reproductive 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 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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It’s You 

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