Chapter-5

FUNDAMENTAL UNIT OF LIFE

CELL
cell is the structural and functional unit of life.

> Cells are called the structural unit of life. Because it provides the structure to our body!
The cell is called the functional unit of life because all the body works are at the cell level.

In 1665, Robert Hook saw the thin cut of the work (wood skins) from the microscope made by the
microscope, (t looks like a honeycomb, which was so many small compartment . (it was a dead cel)
> Robert Brown discovered the nucleus in the cell in 1831.

> Purkinje coined the term protoplasm' for the fluid of the cell in 1839.
> Leeuwenhoek (1674) discovered free-living cells in pond water using an advanced microscope.
Acell---asmall room)
5
All organisms are made up of cells, these are the basic units of life.
For exanmple:- animals, trees, plants, etc.
L
PLANT CELLS (THESE ARE THE CELLS OF TREES AND PLANTS)

CELL OFAN ONION PLANT PEEL

x50

-nucleus
onion skin cell

cytoplasm

cell wall

DIFFERENT TYPES OF CELLS IN ANIMALS

On the basis of no. of cells, organisms are of two types:
() Unicellular Orgarnism
(i) Multicellular Organism
() Unicellular Organism:
These organisms are single celled which perform all the functions. Example: Amoeba, paramecium, bacteria.

() Multicellular Organism:
Many cells grouped together to perform different function in the body and also form various body parts. Example:
fungi plants, animals.
The shape and size of cell are different according to the kind of function they perform. There is division of labour
in cells.

Different between Unicellular Organism and Multicellular Organism

Unicellular Organisms Multicellular Organisms
They are made up of single cell.
The single cell of the organism can
" They are organisms are made up of
many cells.
S
perform all the functions of life. " Division of labour exists among cells.
These organisms are generaly very Different cells are specialized to
small (microscopic) in size. perform different functions.
They lack tissues, organs and organ " They are mostty large in size.
systems. " They are composed of tissues, organs
Growth occurs by an increase in the and organ systems.
size of the cell. . Growth occurs by an increase in the
eg. Amoeba, Paramecium and number of cells by cell division.
Euglena. eg. Earthworms, Fish, Frogs, Lizard
and human beings.

CELLS ARE OF TWO TYPES:

() Prokaryotic cellcell
(1) Eukaryotic cell
Prokaryotic Cell Eukaryotic Cell
Prokaryotic cell has Eukaryotic animal cellis
tough cell wall. |only surrounded by thin
plasma membrane.
|It does not have nucleus. It has a prominent
nucleus in the center.
The cell bears several The cell organelles are
organelles like absent.
mitochondria, golgi
Complex etc.
DNA is circular. DNA is linear, thread like
structure.

E.g. bacterial cells E.g. cells of multicellular

organisms.
Size of the cell

The size of the cell can vary depending on the type of work done by them in any organism.
Cells are able to change their size. For example, white blood cells and amoea can change itself.

There are three main components of the cells

Cytoplasm
1. cell membrane plasma membrane Nucleus
Cell membrane
2. nucleus of celI
Mitochondrion
3. Cytoplasm
1. THE CELL MEMBRANE/ PLASMA MEMBRANE
I. separates it from each other cell.
ASSES
I. This is both in the plant cell and animals cells.
IL. It is made from protein and lipid. It is descriptive permeable,
IV. it gives some substance to the cells inside the cells.
V. Itis flexible.

Function
As it is a select pemeable membrane, allows the flow oflimited substances ina cells.
CELL WALL
. Cell mural it is the most heavy membrane of plant cell.
I. This is not in the animals cells,
II. it is only found only in plant cells.
IV. This is strict thick, sense, death, structure.
V. There are middle festivities between two cell reefs.

VI. It is made up of salulos.

Function
1. It determines the size and hardness of plants'cells.
2. t provides protection to the plasma membrane.
3. This prevents the cells from insects in dryness.
4. It helps in transporting various types ofmaterial inside and outside.
NUCLEUS
I. It controls all the cells of the cell.

II. Echeriotic cells are obscure and obscure center in the processic cells.
II. Its dual centers around the membrane and there are centrifugal money.
IV. There are genetic properties in Centerable Materials are made of
Christians and Chromatin (Structure like thread).
V. The nucleus controls all the chios of the cel.

Function
It controls all metabolic activities from cells.

t controls the cell cycle.

It is a gene storage,
iv. it is related to transmission of hereditary symptoms from parents.

CYTOPLASM
1. It is an aqueous fluid which contains many types of proteins.
2. It is a viscous colourless semi-fluid substance which is located between the plasma membrane and the
nuclear membrane.

Functions
1. The protoplasma serves as a storehouse of important chemicals like amino acids, proteins, sugars,
vitamin C, etc.

2. It is the site of certain metabolic reactions such as glycolysis, synthesis of fats, acids, conservation of
nucleotides, etc.

PARTS OF CYTOPLASM
Organelles of the cell-These are the parts of the cell
which perform various functions to keep the cell alive
1) Endoplasmic reticulum
2) Golgi apparatus
3) Lysosomes
4) Mitochondria
5) Plastids
f
6) Vacuoles
 1. ENDOPLASMIC RETICULUM(ER)
It is a very large system of on and off. It looks like a long tube or a ball.

There are two types of endoplasmic reticulum.

1. Smooth endoplasmic reticulum (SER)
2. Rough endoplasmic reticulum (RER)

1. SMOOTH ENDOPLASMIC RETICULUM (SER) Fough encoplasic

Nuceus
retculun
It is made up of membranes and tubes.

It helps in making ipids and has fewer ribosomes.

2. ROUGH ENDOPLASMIC RETICULUM(RER)

It is made up of vesicles and tubes. It helps in protein synthesis. Smooth erdoclase
etculun
And has more ribosomes.

Functions of endoplasmic reticulum

> It works as a transport between the cytoplasm and the nucleus.

> it provides space for biochemical reactions.

> t helps in the digestion of fats, steroids, cholesterol.
> It helps in eliminating toxins and drugs from the cells.
> The cell membrane is made from some proteins and lipids, this formation process is called bio-genesis.

2. GOLGI APPARATUS Golgi apparatus

Incominggtransport vesicle
cis face

It is a group of thin membrane-bound vesicles, vesicles are cisternae lumen

parallel to each other. Which is called Golgi apparatus (cistern).

Function:
> It packs the material synthesized in ER.
> it forms lysosomes.
> It also stores and modifies the material in vesicles. trans fac

newty loming vesicle secretory vesicle

3. LYSOSOME (Suicidal bag) O Encyckpasa Brtannica Ine

> t is formed by Golgi apparatus. It contains very powerful digestive enzymes.

> It is mnostly found in eukaryotic cells in animals.
Function:
> it cleans the cells.

> t digests the damaged parts of cell organelles.

> It also digests the substance that damages the cells.
> During disturbance in cellular metatbolism,
for example when the cell is damaged, the lysosome
may burst and the enzymes digest their own cell. Lysosome
> So lysosomes are known as suicide bags of a cell.

4. MITOCHONDRIA (Power house)

Cell
It is present only in eukaryotic cells. It is made up of
double membrane, outer membrane is porous and
Mitochondria
inner membrane is folded (with many folds called cristae).
> It contains its own DNA and ribosomes.

> t is absent in bacteria and red blood cells of mammals.

Function
It is the site of cellular respiration hence provide energy
for vital activities of living cells.
> ts main function is to store ATP (energy currency ofthecel). Mitochondrial DNA
> it is also called power hOuse of the cell.

5. PLASTIDS
it is present only in plant cells. They are generally spherical or discoidal n shape and double membrane
bound in organisms.
It also contains its own DNA and ribosomes.

It is of three types.
Leucoplast (chromatoplast)
Chromoplast (chromatoplast)
Chloroplast (chloroplast)
).Leucoplast
These are white in colour and are found in cells
below the ground.
2).Chromoplast
These are reddish brown in colour and are found in stem cells.

3).Chloroplast:
These are green in colour and are found in upper cells (leaf).
Function
1. These produce food through photosynthesis in the presence of sunlight and CO2 to form carbon dioxide.
2. They provide colour to flowers to attract insects for pollination.
3. These store protein, oil and wax.

6. Vacuoles
1. Vacuoles are storage sacs of liquid in solids.
2. Their size is large in plant cells and small in animal cells.
VACUOLES
3. In single cell organisms like amoeba, food material is
stored in the celI.

Function
1. It stores a group of different substances.
2. Like amino acids, sugar, organic acids, and proteins etc.
3. Provides rigidity to the cell
4. Also Works to remove excess water and waste materials

RIBOSOME
Ribosome is a microscopic particle, which synthesizes protein from amino acids. All types of proteins are
produced by ribosomes. They are found on the surface of endoplasmic reticulum, in mitochondria and in
chloroplasts.
Difference between animal cells and plant cells

Animal Cell Plant Cell

Cell wall is absent. Cell wall is present.

Plastids are absent. Plastids are present.

Centrioles are present. Centrioles are absent.

Golgi bodies are present. Golgi bodies are present and called dictyosome.

Vacuoles are absent. If present, they are small. Vacuoles are present and large in size.

Centrosome is present with one or two centrioles. Centrosome is absent