This document provides information about cell structure and organization. It defines cells, tissues, organs and organ systems. It describes key differences between plant and animal cells as well as differences between prokaryotic and eukaryotic cells. It also outlines the structure and functions of important cell organelles including the plasma membrane, cell wall, cytoplasm, Golgi apparatus, endoplasmic reticulum, lysosomes, mitochondria, ribosomes and nucleus. Large vacuoles in plant cells are also discussed.

2. CONTENTS
Organization of cell
cell
tissue
organ
Difference between plant cell and animal cell
Cell structures and their functions:
Plasma membrane and its functions
Cell wall and its functions
Cytoplasm and its functions
Golgi apparatus and its functions
ER and its functions
Lysosomes and its functions
Mitochondria and its functions
Ribosomes and its functions
Nucleus its function and its parts
Vacuoles and its functions
Difference between prokaryotic and eukaryotic
cells

3. Cell
Tissue – group of cells
functioning together.
Organ – group of tissues
functioning together.
Organ System – group of organs
functioning together.
Organism – group of organ
systems functioning together.

4. Cell is the
CELL
basic
structural
and
functional
unit of life. It
is the
smallest unit
of an
organism
that is
classified as
living, and is
often called
the building
brick of life.

5. TISSUE
Group of
cells
working
together
constitute
a tissue.

6. ORGAN
Group of
tissue
working
together
constitute
a organ.

7. DIFFERENCE BETWEEN:
Animal cell Plant cell

8. Animal cell Plant cell
 Animal cells are usually  Plant cells are
smaller in size. comparatively larger in
 Enclosed by plasma size.
membrane only. Cell  Plasma membrane of
wall is absent. plant cells is
surrounded by a thick
cell wall.
 Plastids are absent,
except in the protozoan
euglena.  Plastids are present.

9. Animal cell Plant cell
 Cytoplasm consists  Cytoplasm peripheral,
largely of smaller central space occupied
vacuole. by a large vacuole.
 Nucleus lies in the  Nucleus lies on one
centre. side.
 Prominent and highly  Contains several sub-
complex Golgi bodies units of Golgi
present. apparatus called
dictyosomes.
 Animal cells possess  Plant cells lack
centrosome with one or centrosome and
two Centrioles. Centrioles.

11. This is the outermost
covering of the cell that
separates the contents
of the cell from its
external environment.
Plasma membrane is a
living, thing, delicate,
elastic, selectively
permeable membrane
made up of proteins and
lipids and is present in
both plants and animals
cells.

12.  It gives definite shape to the cell.
 It separates the contents of a cell from its
surrounding medium.
 It provides mechanical barrier for the protection of
the internal contents of the cell.
 It is selectively permeable membrane.
 It regulates the movement of ions in and out of the
cell.

13. Plant cells have a rigid
outer protective covering
called the cell wall which
lies outside the plasma
membrane. The cell wall
is non-living, freely
permeable and mainly
composed of cellulose.

14.  It provides structural strength to the plants cells.
 It permits the cells of plants, fungi and bacteria to
withstand very dilute external media without
bursting.
 It gives a definite shape to the cells.
 Because of cell walls, plant cells can withstand
much greater changes in the surrounding medium
than animal cells.
 Cell wall protects the cells against pathogens and
mechanical injury.

15. It is the fluid part
content of the cell
which occurs between
the plasma membrane
and the nuclear
envelope. It contains
various cell organelles
which perform different
functions of the cell.

16.  Cytoplasm helps in exchange of material between
cell organelles.
 It acts as a store of vital chemicals such as amino
acids, glucose, vitamins, ions, etc.
 It is the site of certain metabolic pathways such as
glycolysis. Synthesis of fatty acids, nucleotides and
some amino acids also take place in the cytoplasm.

17. It is an organelle in animal
cells consisting of a set of
membrane bound smooth,
flattened cisternae stacked
one above the other, large
spherical vacuoles and small
and spherical fluid-filled
vesicles. In the plants, Golgi
bodies are called
dictyosomes. The Golgi
apparatus is the secretory
organelle of the cell. It arises
from the membrane of the
smooth ER.

18.  Storage, modification and packaging of products in
vesicles.
 Formation of complex sugars from simple sugars.
 Secretion is the main function of Golgi complex.
The secretory proteins and lipids are packed and
released on the surface by exocytosis.
 It helps in the formation of cell plate during cell
division.
 The Golgi apparatus is also involved in the
formation of lysosomes and peroxisomes.

19. The endoplasmic reticulum(ER)
is a large network of membrane-
bound tubes and sheets
extending from outer nuclear
membrane to the plasma
membrane. It occurs in the three
forms-
Cisternae, vesicles and tubules.
Depending upon the presence
and absence of ribosome's on the
surface of ER, these are two
types- RER with ribosome's
attached to its surface for
synthesizing proteins.

20.  It gives mechanical support by forming a network in
the cytoplasm.
 ER serves as channels for the transport of
materials between various regions of cytoplasm or
between the cytoplasm and the nucleus.
 Certain enzymes present in the smooth ER fats,
steroids and cholesterol.
 Rough ER is concerned with the transport of
proteins which are synthesized by ribosome's in
their in their surface.

21. These are membrane-bound
vesicular structures found in the
cytoplasm of all eukaryotic
animal cells expect mammalian
RBC’s. Each lysosomes is
surrounded by a single
membrane and contains
powerful digestive enzymes.
These enzymes are made by
RER. Lysosomes are involved
in intracellular digestion of
foreign food or microbes and
are called digestive bags.
These are involved in autolysis
of cells after their death, hence
they are also called suicidal
bags. Lysosomes are a kind of
waste disposal system of a cell.

22.  Lysosomes destroy any foreign material which enter the
cell such as bacteria and virus, thus protect the cells from
infection.
 They help in removing dead and worn-out cell organelles
by digesting them.
 They bring self-destruction of a cell by releasing their
enzymes within the cell. Thus, they act like suicidal bags
in damaged cells.

23. These are rod-shaped
structures present in the
cytoplasm of all the eukaryotes
except mammalian RBCs.
Mitochondria are called power
house of the cells. They store
energy in the form of ATP
molecules by cellular
respiration. It is a self-
replicating organelles. They
contain DNA, RNA and
ribosome's to carry out protein
synthesis. Mitochondria are
the largest organelles in the
animal cells.

24.  Mitochondria are the sites of cellular respiration.
 They provide energy for the vital activities of living
cells.
 Mitochondria are able to make some of their own
proteins, so they are regarded as semiautonomous
organelles.
 They provide intermediates for synthesis of various
chemicals like fatty acids, steroids, amino acid, etc.

25. They are dense, spherical
and granular particles, which
occur freely in the matrix or
remain attached to the
surface of the ER. These are
smallest known electron
microscopic,
ribonucleoprotein particles
found in the cytoplasm of
both prokaryotes and
eukaryotes. Ribosome's are
sites of protein synthesis and
hence are called protein
factories of the cells.

26. Robert brown in 1831
discovered the nucleus is
the largest cell structure.
It is spherical or oval
prominent structure,
usually located in the
centre of the cell.
Nucleus has the following
important parts:

27.  Nuclear membrane: it is a double layered membrane,
which separates nucleus from the cytoplasm. It has
pores called nuclear pores which allow the transfer of
material from inside the nucleus to the cytoplasm.
 Nucleolus: it is a homogeneous and granular dense fluid
present inside the nucleus to the cytoplasm.
 Chromatin material: it consists of long, coiled network of
thread-like structures. The chromatin material is made
up of DNA which is responsible for storing and
transmitting the hereditary information from one
generation to the other. It condenses into compact rod-
like bodies called chromosomes at the time of cell
division.
 Nucleolus: it is more or less round structure found inside
the nucleus. The nucleolus contains RNA and
proteins.RNA is helpful in protein synthesis in the
cytoplasm.

28. There are fluid-filled or solid
filled membrane bound
spaces in cytoplasm. In
animal cells, they are small-
sized and many, but in plant
cells, a single prominent very
large vacuole occupies about
50-90% of the cell volume. In
the plant cells, vacuole is
bounded by a membrane
called tonoplast. The vacuole
is filled with cell sap which is
a watery solution rich in
amino acids, sugars, various
organic acids and some
proteins.

30. Prokaryotic cell Eukaryotic cell

31. DIFFERENCE BETWEEN:
Prokaryotic cells Eukaryotic cells
 Size of the cell is  Size of the cell is
generally small. generally large.
 Nuclear region is  Nuclear region is well-
poorly defined due to defined and
absence of nuclear
membrane and known surrounded by a
as nucleoid. nuclear membrane.
 It contains single  It contains more than
chromosome.
one chromosome.
.

32.  Nucleolus is absent.  Nucleolus is present.
 Membrane bound cell  Cell organelles such as
organelles are absent. mitochondria, plastids,
ER, lysosomes,etc are
present.
 Cell division occurs by
meiotic cell division.
 Cell division takes
 Centrioles are present
place by budding.
in animals cells.
 Centrioles absent.
 Eukaryotic cells are
 Prokaryotic cells are
found in fungi, plant
found in bacteria, blue- and animal cells.
green algae.