This is a Presentation describing the structure and different functions of many cell organelles. This describes cells, types of cells, prokaryotic cells, eukaryotic cells, cell membrane, cytoplasm, mitochondria, nucleus, nucleolus, vacuoles, endoplasmic reticulum, Golgi apparatus, ribosomes, lysosomes, cell wall, and plastids.

1. PRINCEPRINCE SAINISAINI
CLASS-CLASS-IXIX ‘A’‘A’
SUB-SUB-SCIENCESCIENCE
TOPIC-TOPIC-STRUCTURE ANDSTRUCTURE AND
FUNCTIONS OF CELL ORGANELLESFUNCTIONS OF CELL ORGANELLES

2. 1. Cells
• Cells are the basic unit of all living things.
• Cell Theory:
•All organisms are made up of one or more cells.
•The cell is the basic unit of all organisms.

3. 2. Two Types of Cells
Eukaryotic cell Prokaryotic cell

4. 2.1 Prokaryotic cell
• It is a single celled organism that does not have a nucleus or
membrane bound organelles.

5. 2.2 Eukaryotic Cells
• There are 4 classes of eukaryotic cells.
• We will discuss only 2; Plant & Animal cells -
Plant Cell Animal Cell

6. Cell
Organelles
and Their
Functions

7. 3.1 Cell Membrane
• The outermost covering of the cell that separates the
contents of the cell from its external environment is
known as cell membrane. It is selectively permeable
and is made up of bilayer of lipoprotein.
• The cell membrane holds the cell together and allows
nutrients into the cell.

8. 3.2 Cytoplasm
• The fluid or matrix content inside the plasma membrane of a cell
along with the cell organelles is known as cytoplasm.

9. 3.3 Mitochondria
• It is an cell organelle found in large numbers in most cells,
in which the biochemical processes of respiration and
energy production occur. It has a double membrane, the
inner part being folded inwards to form layers (cristae).

10. 3.3.1 Functions of Mitochondria
• It is the site for respiration.
• The energy required for various chemical activities needed
for life is released by mitochondria in the form of ATP
molecules.
• They have their DNA and ribosomes due to which they are
able to make some of their own proteins. Thus, they are
regarded as semiautonomous organelles.

11. 3.4 Nucleus
•The nucleus controls the cell.
•It is the largest organelle in the cell and contains
the cell’s DNA.

12. 3.4.1 Functions of Nucleus
• It helps in inheritance of features from parents to next
generation in the form of DNA molecules present in
chromosomes which are present in it.
• It controls which protein and what amount of it will be
synthesized in the cell.
• It plays a central role in the cell division.
• It plays a crucial part, along with the environment, in
determining the way the cell will develop and what form it
will exhibit at maturity and what function it will do, by
directing the chemical activities of the cell.

13. 3.5 Nucleolus
•Inside the nucleus, there is another organelle
called the nucleolus.
•It is responsible for making ribosomes.

14. 3.6 Vacuoles
•They are storage sacs for solid or liquid contents
bounded by a unit membrane.
•In animals they are present in large number but
their size is small.
•While plants have very few vacuoles but their size
is large.

15. 3.6.1 Functions of Vacuoles
• They are storage sacs of the cells.
• Many important substances like amino acids, sugars, various
organic acids and some proteins are present in the vacuoles
of plants.
• In single celled organisms like Amoeba, food vacuoles
contains the food items that the Amoeba has consumed.
• In some unicellular organisms, specialised vacuoles also play
important roles in expelling excess water and wastes from
the cell.

16. 3.7 Endoplasmic Reticulum
• It is a large network of membrane bound tubes and sheets. It looks like
long tubules or round or oblong bags(vesicles).
• There are two types of endoplasmic reticulum:
1. Rough Endoplasmic Reticulum: It has particles called ribosomes
attached to its surface. Thus, it looks rough under a microscope and is
known as rough endoplasmic reticulum.
2. Smooth Endoplasmic Reticulum:
It looks smooth because it doesn’t have
ribosomes on its surface and
is known as smooth
endoplasmic reticulum.

17. 3.7.1 Functions of Endoplasmic
Reticulum
• Rough Endoplasmic Reticulum is a site for protein synthesis.
• Smooth Endoplasmic Reticulum is a site for lipid synthesis.
• Some of these proteins and lipids synthesized by RER and SER
respectively help in the process of building the cell membrane
which is known as membrane biogenesis.
• It serves as channels for the transport of materials from
nucleoplasm to cytoplasm or from one part of the cytoplasm to
the another part of the cytoplasm.
• SER in the liver cells of the group of animals called vertebrates
plays a crucial role in detoxifying many poisons and drugs.

18. 3.8 Golgi apparatus
• It is organelle in the cell that is responsible for sorting and
correctly shipping the proteins produced in the ER.
• Golgi Apparatus is made up of membrane bound vesicles
present in the form of stacks. Such structures are called
cisterns.
• It was discovered by Camillo Golgi.

19. 3.8.1 Functions of Golgi Apparatus
• Storage, packaging and dispatching of the substances formed by SER
and RER.
• Formation of complex sugars from simple sugars.
• Formation of lysosomes.

20. 3.9 Ribosomes and Its Functions
• These are tiny particles present in all active cells and act as
the active sites for protein synthesis.
• Organelles that help in the synthesis of proteins.
• Some ribosomes are found in the cytoplasm, but most are
attached to the endoplasmic reticulum.

21. 3.10 Lysosomes and Its Functions
• These are membrane bound cell organelle that contains
digestive enzymes.
• When the cell gets fully damaged, lysosomes may burst and the
enzymes digest their own
cell. Therefore, lysosomes are also
known as suicide bags of
cell.
• Lysosomes function as the
cell's recycling compartment.

22. 3.11 Cell Wall
•Plant cells, in addition to the plasma membrane,
have another rigid outer covering called the cell
wall. It lies outside the plasma membrane.
•Cell walls are only
present in plants,
fungi and bacteria.
•Cell wall is mainly
composed of cellulose
which is a type of
complex carbohydrate.

23. 3.11.1 Functions of Cell Wall
•Cell wall permit the cells of plants, fungi and
bacteria to withstand very dilute(hypotonic)
external media without bursting.
•It has narrow pores through which fine strands of
cytoplasm are able to cross the cell walls.
•Because of cell wall, cells can withstand changes in
the external environment, protecting the
constituents of cell.

24. 3.12 Plastids
• These are found only in plant cell. They are double layered
and contain their own DNA and ribosomes.
• Plastids are of three types:
1.Chloroplasts: These are the plastids containing chlorophyll
which gives green colour to the plant. It is also a
semiautonomous organelle.
2.Leucoplasts: These are the white or colourless plastids.
They can change to other types of plastids.
3.Chromoplasts: These are coloured plastids.

25. 3.12.1 Functions of Plastids
1) Chloroplasts: These are important for photosynthesis in
plants.
2) Leucoplasts: These store materials like starch, oils and
protein granules.
3) Chromoplasts: These impart colour to flowers and fruits.
They are rich in carotenoid pigments and lipids.