CHAPTER 2 : CELL STRUCTURE & CELL ORGANISATION 2.1 Cell Structure & Function 2.2 Cell Organisation

form4(BIOLOGY) chap 2 pt1

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2.1 Cell Structure & Function2.2 Cell Organisation

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Learning Outcomes :1. Draw & label an animal cell and a plant

cell2. Identify the cellular components of an

animal cell & a plant cell3. State the functions of the cellular

components in an animal and a plant cell4. Compare & contrast an animal cell with a

plant cell5. Relate the density of certain organelles

with the functions of specific cells.

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HISTORY Robert Hooke (1665) was first

discovered the cell structure of plant

He examined fine slices of cork with a primitive microscope

He saw many ‘box-like’ structures , then he called ‘cells’, from Latin for ‘little rooms’.

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THE CELL THEORY(Schleiden M & Schwann T)

All living organisms are made up of one or more cells

New cells are formed by the division of pre-existing cells

Cells contain genetic material of an organism which is passed from the parent cells to daughter cells

Cells are the basic unit of structure & function in living things

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ORGANELLES specialised structures which are each surrounded by its own membrane & perform specific function

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Thin, semi-permeable Made of protein, lipid Controls the

movement of substances in and out of the cell


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CYTOPLASM Jelly-like substance

that contains water & mineral salts

Contains organelles and food such as carbohydrates (glucose)

Medium for metabolic reactions

Supplies the substances required by organelles


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CELL WALL Thick layer outside

the plasma membrane Made up of cellulose,

fully permeable Maintains the shape

of the plant cells Provides mechanical

support Non-organelle

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NUCLEUS Spherical shape with

double membrane Contains nucleolus,

chromosomes, nucleoplasm & nuclear membrane

Controls & regulates all the activities of cell

Contain the heredity factors responsible for the traits

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RIBOSOME Small particles

consisting of RNA Exists freely in the

cytoplasm or on the surface of the endoplasmic reticulum

Synthesis of protein

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ENDOPLASMIC RETICULUM A system of membrane-

enclosed tubules closely packed together and continuous with the nuclear membrane

RER has ribosome, SER does not have

Transport system for protein & lipids within the cell

RER transport protein to other part of cell

SER stimulates the synthesis of lipids & cholesterol & transport within the cell

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GOLGI APPARATUS Vacuolar region

surrounded by a complex meshwork of vesicles budding off at its end

Received protein & lipids from ER & modify them to form specific secretion such as enzymes & hormones

Pack the secretions formed into secreting vesicles & transport them to plasma membrane to be secreted

Controls the secretory activity of cells

Formation of lysosomes

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VACUOLE Filled with cell sap,

surrounded by semi-permeable membrane called the tonoplast

Contain water, sugar & dissolved minerals

Maintain turgidity of cells in plants

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MITOCHONDRIA Rod-shape with a

double membrane Outer membrane is

smooth, inner membrane is folded to form cristae

Known as ‘power-house’ of the cell

Releases energy as it is the site for aerobic respiration

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CHLOROPLAST Disc-shape organelle

with a double membrane

Consist of an orderly arrangement of grana within the stroma. Granum contains chlorophyll

Site of photosynthesis Trapped light energy

and change it into chemical energy

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LYSOSOMES Membrane-bound

vesicles found in animal cells

Contain enzymes which control breakdown of protein & lipids

Contain enzymes that digest aged or defective cell components or materials taken in by the cell from its environments such as food particles or bacteria.

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CENTRIOLES A pair of small

cylindrical structures (microtubules)

Form spindle fibre for cell division

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A plasma membrane surrounding the cytoplasm

Both contain nucleus & cytoplasm

Both contain organelles such as mitochondria, ER, Golgi apparatus &


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cellSIZE Larger than animal

cellIrregular shape SHAPE Often regular in

shapeAbsent CELL WALL PresentAbsent CHLOROPLAST Present

No large vacuoles. If present, small &


VACUOLES Large central vacuole filled with

cell sapIn a form of glycogen

in liver & muscle tissues

FOOD STORAGE In a form of starch

Present CENTRIOLES AbsentSome animal cell

have cilia or flagellaCILIA & FLAGELLA Absent

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The number of specific organelles in a cell varies on the type of cell and its function.

Active cell many mitochondria to provide enough energy for its activities. Eg. : sperm cells, flight muscle cell (insects & birds)

Cell in meristems of plant shoot & root

Green plants more chloroplasts to carry out photosynthesis such as palisade mesophyll cells and spongy mesophyll cells, also guard cells.

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EXERCISE 2.11. What are the organelle structures of a


2. What are the functions of each structure describe above?

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