This document provides an overview of cell structure and function. It discusses that the cell is the fundamental unit of life, and all cells perform basic functions like respiration and nutrition. The key components of a cell are then described in more detail. This includes the plasma membrane, nucleus, cytoplasm, and various organelles within the cell and their functions. Specifically, it outlines the roles of the endoplasmic reticulum, Golgi apparatus, lysosomes, mitochondria, chloroplasts, and ribosomes. The document concludes by distinguishing between prokaryotic and eukaryotic cells.

1. THE FUNDAMENTAL UNIT OF LIFE: CELLS
PRESENTED
BY
RACHIT
AHUJA
CLASS-9-C

2. Cell is the basic structural & fundamental unit of life. All
cells whether they exist as called organisms or as part ,
Perform similar basic functions such as respiration and
nutrition, which are essential for their survival

3. • The cell is the smallest unit of
life.
• All organisms are composed one
or more cells.
• New cells arise from previously
existing cells.

4. What is cell Made up of?
A cell is a tiny mass of protoplasm which is
surrounded by a membrane & is capaable of
performing all functions of life .
A typical cell is formed of three pairs:
1.Plasma membrane or cell- membrane
2.Nucleus
3.Cytoplasm

5. 1. Plasma membrane
This is the outermost covering of the cell that separates the contents of
the cell from its external environment. The plasma membrane allows
or permits the entry and exit of some materials in and out of the cell.
The cell membrane , therefore is called a selectively permerable
membrane.

6. Functions of the plasma
membrane
1.It gives definite shape to cell
2.It seprates the contents of the cell from its
surrounding medium
3.It provides mechanical barrier for the
protection of the internal contents of the cell
4.It is selectively permerable
5.It regulates the movement of ions in and out
of the cell

7. NUCLEUS

8. The Nucleus
The nucleus is a membrane bound structure that contains the
cell's hereditary information and controls the cell's growth and
reproduction. It is commonly the most prominent organelle in
the cell
The nucleus is surrounded by a structure called the nuclear
envelope. This membrane separates the contents of the
nucleus from the cytoplasm. The cell's chromosomes are also
housed within the nucleus. Chromosomes contain DNA which
provides the genetic information necessary for the production
of other cell components and for the reproduction of life.

9. Functions of the nucleus
1. The nucleus controls all metabolic activities of
the cell
2. It regulates the cell cycle
3. It is concerened with the transmission of
heredity traits from the parent offsprings

10. Cells
Two fundamental types:
1. Prokaryotic
2. Eukaryotic

11. Prokaryotic Cells

12. Prokaryotes
 1. Prokaryotic cells are less complex
 2. Unicellular
 3. Do not have a nucleus
 4. Most have a cell wall surrounding the cell
membrane
 5.Include bacteria & blue- green bacteria

13. Typical Animal Cell
Eukaryotic Cells

14. EUKARYOTES
1. More complex cells
2. Includes both multicellular and unicellular
organisms.
3. Do have a true nucleus
4. Organelles are internal structures in cell’s that
perform specific functions
5. Eukaryotes include plant cells, animal cells,
fungi, algae, and protists.

15. The Cytoplasm

16. Cytoplasm
 The protoplasmic mass of the inner cell to
plasma membrane and excluding nucleus is
called cytoplasm. When the cell is young , the
cytoplasm completely fills the space between
nucleus and plasma membrane. As it
increases in size, a number of small cavities
called vacuoles appear in the cytoplasm. It
also contains many specialised cell
organelles. Each of these organelles performs
a specific function for the cell.

17. Cell organelles
 Every cell has a membrane around it to keep its
own contents separate from the external
environment. Large and complex cells, including
cells from multicellular organisms, need a lot of
chemical activities to support their complicated
structure and function. To keep these activities of
different kinds separate from each other , these
cells use membrane bound little structures (or
organelles) within themselves.

18. Types of organelles
1.ENDOPLASMIC RETICULUM
2. GOLGI APPARATUS
3. LYSOSOMES
4. MITOCHONDRIA
5. PLASTIDS
6. VACUOLES

19. The Endoplasmic Reticulum

20. Endoplasmic reticulum
 This is a complex network of tubes, the lumen
of which is filled with fluid. The two types of
endoplasmic reticulum are seen .
They are;-
1. Rough endoplasmic reticulum
2. Smooth endoplasmic reticulum

21. Functions of the (RER) & (SER)
 RER looks rough under a microscope
because it has particles called ribosomes
attached to its surface. The ribosomes , which
are present in all active cells , are the sites of
protein manufacture.
 SER helps in the manufacture of the fat
molecules , or lipids, important for cell
function. Some of these proteins & lipids
helps in building the cell membrane.

22. The Golgi Apparatus

23. The Golgi Apparatus
 Also known as golgi complex or golgi bodies ,
they consists of tiny elongates , flattened sacs
(cisternae) , which are sacked parallel to one
another along with some vacuoles and
clusters of vesticles.
 The function of the golgi body is to secrete
certain hormones and enzymes . it also forms
lysosomes . The golgi body is usually found
close to the nucleus.

24. LYSOSOMES
 These are membrane bound vesicular structures found in
the cytoplasm . Each lysosome 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 or self- digestion of cells after their
death, hence they are also called SUICIDAL BAGS. They
are a kind of waste disposal system of a cell.

25. Ribosomes
Cells need to make proteins. Those proteins
might be used as enzymes or as support for
other cell functions. When you need to make
proteins, you look for ribosomes. Ribosomes are
the protein builders or the protein synthesizers
of the cell. They are like construction guys who
connect one amino acid at a time and build long
chains.
Ribosomes are found in many places around the
cell. You might find them floating in the
cytoplasm (cytosol). Those floating ribosomes
make proteins that will be used inside of the cell.
Other ribosomes are found on the endoplasmic
reticulum. Endoplasmic reticulum with attached
ribosomes is called rough. It looks bumpy under
a microscope. Those attached ribosomes make
proteins that will be used inside the cell and
proteins made for export out of the cell.

26. Mitochondrion

27. Lysosome Function

28. Chloroplasts

29. THANK
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