Cell

B M Subramanya Swamy M.Sc. B.Ed.

CIE Co ordinator & Examination OfficerKanaan Global School

Jakarta Indonesia

swamy@kanaanglobal.sch.id

Introduction

• A cell is the basic unit of structure and function in an organism

• All organisms are unicellular or multicellular

• It is a smallest living unit showing all the characteristic of life and performing all the vital functions

Animal cell

Structure Function

Cell Membrane Also called plasma membrane

A thin delicate layer made of layers of proteins and fats

Completely surrounds and holds in the constituents of the cell

High surface area of the cell provides for absorption of nutrients and the disposal of wastes

Differentially permeable controlling the transport of materials in and out of the cell

Allow certain small substances like glucose water and oxygen to enter the cell

Prevent larger molecules like protein and starch from leaving the cell

Structure Function

Nucleus Most prominent structure of the cell

Usually spherical in shape

Found near the centre of the animal cell

Bound by two membranes forming the nuclear envelop

Isolates the genetic material from the rest of cell

Nuclear pores are scattered over the surface of this envelop

Found within the nucleus is one or more small spherical structure called the nucleolus which is not bound by a membrane

Nucleoplasm is the cytoplasm like material that fills up the nucleus .it contains chromatin which is made up of DNA

Involved in cell division

Controls all cellular activity

Houses the organisms genetic material

Nuclear pores act as channelsPermitting certain molecules to enter or leave the nucleus

Structure Function

Cytoplasm Jelly like substance

Fills up the cell

Suspension of various organelles

It is here that metabolisms takes place

Organelles Structure Functions

Vacuoles Sacs filled with cell sap a watery solution of sugars salts and pigments

Some function during digestion eliminating excess water entrapping food particles or for discharging wastes

Structure Function

Mitochondria Rod shaped organelles Structure with the inner folded membranesPermanent structure in the cell

Power house of the cell

Site for aerobic respiration which generates energy for all the cellular activities

Inner folds carry respiratory enzymes which help to control respiration and the release of energy from glucose molecules in the cell

Involved in chemical energy conversion during metabolic activities of the cell

Ribosomes

• Translate the genetic code into proteins.

• Found attached to the Rough endoplasmic reticulum or free in the cytoplasm.

• 60% RNA and 40% protein.

Rough Endoplasmic Reticulum

• Network of continuous sacs, studded with ribosome's.

• Manufactures, processes, and transports proteins for export from cell.

• Continuous with nuclear envelope.

Golgi Apparatus

• Modifies proteins and lipids made by the ER and prepares them for export from the cell.

• Encloses digestive enzymes into membranes to form lysosomes.

Lysosomes

• Single membrane bound structure.

• Contains digestive enzymes that break down cellular waste and debris and nutrients for use by the cell.

Centrioles

• Found only in animal cells.

• Self-replicating• Made of bundles of

microtubules.• Help in organizing cell

division.

Structure Function

Protoplasm Combination of all the living parts of the cell

Cells with protoplasm is regarded as living

Starch grainsStructure Function

Insoluble carbohydrates

Occurs as very small grains

Food source for plants

Cell wallStructure Function

Rigid wall made up of a layer of cellulose Provides support and shape to the individuals

vacuoleStructure function

Large compartments

Known as a sap vacuole

Filled with a fluid called cell sap

Membrane that surrounds the vacuole called a Tonoplast

Plays a role in osmoregulation

Maintaining the shape of the cell

Chloroplast Structure Function

Collection of organelles known as plastids

Plastids that store chlorophyll are known as chloroplast

Characteristically green

Absorption of sunlight

Required to carry out photosynthesis

Compare and contrast plant and animal cells

Structures Plant Animal

Cell wall Rigid cell wall made of cellulose. It determines the size and shape of the cell. It also helps to support and strengthen the plant

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Structures Plants Animals

Starch grains Stores food as starch

Can be found in plastids

Excess carbohydrate is stored as glycogen granules

Sap vacuole Large and centrally located It is usually filled with cell sap

Small in size There may be some food vacuole or contractile vacuoles present

Tonoplast This is the membrane that surrounds the sap vacuole formed by a layer of cytoplasm

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Chloroplast Found in green leaves actually it gives the leaf the characteristic green color

It contains chlorophyll to trap light energy for photosynthesis

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Function of the cell membrane• The cell membrane is a thin layer of proteins

and fats around the cell• It surrounds the living cells• Separates one cell from another adjacent cell• Controls and regulates the passage of

substances in and out of the cells• Control the exchange rate of substances in

order to maintain normal conditions inside the cell

Prokaryotic Cells

• Believed to be the first cells to evolve.• Lack a membrane bound nucleus and

organelles.• Genetic material is naked in the cytoplasm• Ribosome are only organelle.