CellThe Cell is the structural and

functional unit of life.All living organisms are made up of cells.It is the smallest living entity found in living organisms.

Cell was introduced by Robert Hooke in 1665

Pattern of cells

Properties of cellThe Cell is the smallest living unit of life.It is so small that it is not visible to the naked eye.The shape of the cell varies in different organisms and within an organism.Size of cells also differs.All living cells exhibit certain basic properties like respiration, growth, metabolism etc.Cells originate from a pre-existing cell. A mother cell divides to produce daughter cells. Hence, cells exhibit cell division.

Unicellular Organismsuni means single

The organisms which are made up only of a single(one) cell.

Eg. Amoeba, chlamydomonas, paramoecium and bacteria

Amoeba contains only one cell

Single cell

Multicellular Organisms

multi means many• The organisms which are

made up of more than one cell.

Eg. Animals,plants,insects,birds,lizards

The three main parts of a cell:-

Plasma (cell) memberane NucleusCytoplasm

Cell memberane

Nucleus

Cytoplasm

Main parts of a cell

Plasma membrane

It is the outermost cover of the cell that separates the content of the cell from the surrounding

Cell membrane is called selectively permeable membrane

Because it allows or permits the entry and exit of some specific materials in and out of the cell

Cell wall or plasma membrane

Content of cell

surrounding

water

O2 and CO2

You can not go outside

Gases like O2 and CO2 move in and out of the cell by the

process of DIFFUSION

Diffusion : It is the intermixing of the particles

of two matters

MATTER-1 MATTER-2

After diffusion

The things always move from more to less quantities

In and out of O2 and CO2

It occurs by the process of DIFFUSION

As soon as there is difference in the concentration of O2 or CO2 inside and outside of the cell, O2 or CO2

moves from a region of high to low concentration region

If the concentration of CO2 or O2 is low in cell than

outside, then the gases will go inside the cell and if

reverse happens then gases will go outside the cell.

Exchange of gases

O2 or CO2

Cell

Osmosis

It is the flow of water from a region of high water

concentration to a region of low water concentration

through a semi permeable membrane

Movement of water

In and out of water occurs by the process of OSMOSIS

If we put an animal cell or a plant cell into a solution of sugar or

salt in water

Three things may happen

If the concentration of water is low in cell than surrounding, the water will move from outside to the cell and it will swell up and such a solution is called Hypotonic solution

Water in the solution

Water in the cell

Hypotonic solution

Flow of water from solution to cell

Surrounding of cell

Solution of sugar in water

If the concentration of water is same in cell as that of surrounding, there will be no net movement of water and solution is called isotonic solution

Water in the solution

Water in the cell

Isotonic solution

Same water concentration in solution and cell

Surrounding of cell

Solution of sugar in water

If the concentration of water is higher in cell than surrounding, the water will move from inside to the solution and it will shrink and such a solution is called Hypertonic solution

Water in the solution

Water in the cell

Hypertonic solution

Surrounding of cell

Solution of sugar in water

Flow of water from cell to solution

Applications of osmosis

Unicellular fresh water organisms and most plant cells gain water

through osmosisMovement of water from roots to

other parts of plants occurs by osmosis

Cell wallThis is the extra or additional rigid cover to the plasma or

cell membrane. It is found only in plant cells

Cell memberane

Cell wall

PLASMOLYSIS

When a living plant cell loses water

through osmosis, there is a shrinkage in

the contents of the cell. This phenomenon

is known as plasmolysis

THE NUCLEUSThe nucleus has a double layering cover called nuclear membrane.Nuclear membrane has pores which allows transfer of material from nucleus to cytoplasm

Nucleus contains chromosomes which are

rod-shaped structures

chromosomes are composed of DNA and proteins

Importance of chromosomes

They contain information for the inheritance from

parents to next generation in the form of

DNA

DNA-Deoxyribo

Nucleic Acid

Functional parts of DNA are called GENES

GenesDNAChromosomes

Prokaryotes

Organisms whose cell has not the nuclear

membrane are known as Prokaryotes eg.

bacterias

In prokaryotic organisms cell has not nuclear

membrane and nuclear region contain only nucleic acids and called nucleoid

Eukaryotes

Organisms with cell having the nuclear

membrane are known as Eukaryotes eg.

Animals,plants

Prokaryotic Cell Eukaryotic Cell

1. Size is generally small

1. Size is generally large

2.Nuclear region is undefined and called nucleoid.

2.Nuclear region is well defined and surrounded by a nuclear membrane.

3.They have single chromosome.

3.More than one chromosome.

4.Membrane-bound cell organelles are absent

4.Membrane enclosed organelles

organellesNucleus

membrane

Cell Organelles

Endoplasmic Reticulum(ER)

Smooth Endoplasmic

Reticulum(SER)

Rough Endoplasmic Reticulum(RER)

RERIt looks rough under a microscope

because it has particles called ribosomes attached to its surface.

Ribosomes are the sites of protein manufacture

The manufactured proteins are then sent to various places in the cell.

SERIt helps in the manufacture of fat

molecules or lipidsSome of these molecules or lipids help in building the cell

membrane. This Process is known as membrane biogenesis.

Golgi ApparatusThe material manufactured near the ER is packaged and dispatched to various targets

inside and outside the cell through the golgi apparatus

FunctionIt includes the storage, modification and packaging of products in vesiclesIt is also involved in the formation of lysosomes

SER

RER Golgi Apparatus

proteins

Fat or lipids

LysosomesFunctions:-

They help to keep the cell clean by digesting any foreign material such as bacteria or food or old cell organelles.They are able to do so because they contain powerful digestive enzymes

Lysosomes are known as “Suicide bags of a cell”

During any disturbance in cell, cell gets damaged.because of that lysosomes may burst and the enzymes digest their own

cell.

Lysosomes

Old cell organelles

Foreign materials

MitochondriaThey areknown as the “Powerhouse of the cell”

The energy required for various chemical activities needed for life is

realeses by mitochondria in the form of ATP

ATP-Adenosine triphopshateATP is known as the energy

currency of the cellOur body uses energy stored in ATP

for making new chemical compounds

ATP

Mitochondria are strange organelles

Because they have their own DNA and ribosomes

Therefore they are able to make their own proteins.

Plastids

•They are present only in plant cells.

Plastids

Chromoplsts(coloured plastids)

Leucoplasts(white or colourless

plastiids)

Plastids containing the pigment chlorophyll are known as chloroplasts.

Like mitochondria,Plastids also have their own DNA and ribosomes

VacuolesThey are storage sacs(pouch)

for solid or liquid contentsVacuoles are small in size in

animal cells while they are large in plant cells.

Many substances of importance in the life of plant cell are stored in

vacuoles eg. Amino acids,sugars,proteins etc.

In Amoeba, the Food vacuole contain the food items that the

amoeba has consumed