This presentation file contains all about cell discovery, cell theory, organelles which are present within the cell and cell comparison between prokaryotic and Eukaryotic organisms.

2. Cell:
• A cell is the structural and functional unit of life
• It is the smallest unit that can do all activities of life. Cells are building blocks of
complex multi cellular organisms.
• All living things, weather Plants, Animals, People, or tiny microscopic organisms, are
made up of cells.
• Although a cell is only about 10 micrometer across.
Cell Discovery:
Robert Hooke:
ROBERT HOOKE discovered the cell in 1665 under his self made compound
microscope and published his work on cell in Micrographia.
He observed thin section of cork (dead plant material).
He said Cell is an empty space surrounded by thick wall)

3. Composition of the Cell
A German Zoologist THEODER SHEWAN
(1839) and a botanist Schleiden (1838)
worked on cell. They found a cell has 3 parts:
1. Plasma Membrane
2. Cytoplasm
3. Nucleus
They said that the cell wall is an additional
structure and present only in plant cell.
All living organism are composed of cell
and cell product.
Later on many other cell organelles got
discovered.

4. Cell Theory
Theoder Schwann and Schleiden purposed Cell theory in
1839.
Cell Theory explain that:
1. All organisms are composed of one or more cells.
2. All cells arise from pre-existing cells.
3. Cell is the structural and functional unit of all the
organisms.
Animal Cells:
Can not make their own food so they have to eat food. Do not go through
photosynthesis. Animal cells are more round shaped. Animal cells have lysosomes.
Animal cells can not make sugar. Animal cells use mitochondria to release energy.
Animal cells do not have a cell wall. Animal cells do not have a large vacuole. They do
not have chloroplast.

5. Prokaryotic Cell
Prokaryotic cells were here first and for billions of
years were the only form of life on Earth. All
prokaryotic organisms are unicellular.
They don't have well defined Nucleus
They appeared on earth long after prokaryotic cells
but they are much more advanced. Eukaryotic
organisms unlike prokaryotic can be unicellular or
multicellular.
They have well defined nucleus.
These organisms are called Prokaryotes. Prokaryotes
do not have a nuclear membrane . Their circular
shaped genetic material dispersed throughout
cytoplasm.
These organisms are called Eukaryotes. Nuclear
membrane surrounds linear genetic material (DNA).
They lack membrane bound organelles having a
simple internal structure. Prokaryotes are smaller in
size when compared to Eukaryotes.
They contain all the membranous bound organelles.
They are large in size then Prokaryotes.
They have small ribosome of 70S. They have large ribosomes of 80S.
These are Primitive Organisms These are advanced organisms. Eukaryotic cells
appeared approximately one billion years ago.
Examples Include bacteria, blue green algae etc. Examples Include Animals , Plants , Fungi etc.
Eukaryotic Cell
Difference in Prokaryotic and Eukaryotic Cell

6. Comparison Between Prokaryotic and Eukaryotic Cells:
• Characteristic Prokaryotes Eukaryotes
• Size of cell Typically 0.2-2.0 mm in diameter Typically 10-100 mm in diameter
• Nucleus No nuclear membrane or nucleoli True nucleus & nucleoli
• Membrane-enclosed Absent Present
• Organelles Absent Present
• Flagella Consist of two protein building blocks Complex
• Glycocalyx Present as a capsule or slime layer Present in some cells that
lack a cell wall
• Cell wall Usually present; chemically complex When present, chemically Simple
• Plasma membrane No carbohydrates and generally Sterols and carbohydrates.
lacks sterols that serve as receptors
• Ribosomes Smaller size (70S) Larger size (80S);
• Chromosome (DNA) Single circular chromosome; Multiple linear chromosomes
• Arrangement lacks histones with histones
• Cell division Binary fission Mitosis
• Sexual reproduction No meiosis; transfer of DNA Involves meiosis
fragments only (conjugation)

7. Plasma membrane:
It is a membrane around the cell, is semi-permeable, meaning that some substances are
able to enter the cell through it and some are not . It involves in the protection of cell.
Plasma Membrane is the outer boundary of cell. It separates the internal metabolic
events from environment. The plasma membrane also has specific receptors for external
molecule that alter the cell function.
Structure and Chemical composition of Plasma membrane:
under Electron microscope it is a bi-layered structure. This structure is delicate and
elastic . It has some ability to repair itself. It is composed of following components.
1. protein 60 to 80 %.
2. Lipids 20 to 40%
3. Small quantity of carbohydrates.
Functions of Plasma membrane:
1.Protective function (Cell membrane protects the cytoplasm and the organelles), 2.Selective
permeability (Cell membrane acts as a semipermeable membrane, which allows only some
substances to pass through it and acts as a barrier for other substances), 3.Absorptive function
(Nutrients are absorbed into the cell through the cell membrane).

8. Functions of Plasma membrane:
4.Excretory function (Metabolites and other waste products from the cell are excreted out
through the cell membrane), 5.Exchange of gases (Oxygen enters the cell from the blood and
carbon dioxide leaves the cell and enters the blood through the cell membrane), 6.Maintenance
of shape and size of the cell (Cell mem-brane is responsible for the maintenance of shape and
size of the cell).

9. Discovered by De Duve in 1949.
He first time isolated Lysosomes as a separate component. The
Word Lysosome is a combination of two words ''Lyso'' means
''splitting'' and ''Soma'' means ''Body''.
It is a Sac-like membrane filled with enzymes involve in cleaning
action of the cell. It consist of a single phospholipid bilayer.
Lysosomes are cytoplasmic organelles found in Eukaryotic cells.
Lysosomes are membrane-enclosed organelles that contain an
array of enzymes.
Lysosomes function as the digestive system of the cell, serving
both to degrade material taken up from outside the cell and to
digest obsolete components of the cell itself. In their simplest
form, lysosomes are visualized as dense spherical vacuoles.
Lysosomes:

10. • Lysosomes are of two types: Primary and Secondary
Types of Lysosomes:
Primary Lysosome:
The Lysosomes which are bud off from the golgi
apparatus are primary lysosomes. Primary
lysosomes contain acid phosphate and hydrolytic
enzymes. These enzymes are synthesized on RER.
SECONDRY LYSOSOMES:
Lysosomes protect the cells from any foreign object
which are engulfed in the cell as phagocytic
vacuoles. These fuse with primary lysosomes to
form digestive vacuole known as secondary
lysosomes, in which various lysosomes enzymes
digest various components of vacuole.

11. Some important functions of lysosomes are
given as:
In phagocytosis, specialized cells, such as
macrophages, take up and degrade large
particles, including bacteria, cell debris, and
aged cells that need to be eliminated from
the body. Such large particles are taken up
in phagocytic vacuoles (phagosomes),
which then fuse with lysosomes, resulting in
digestion of their contents.
In autophagy, internal organelles (such as
mitochondria) are enclosed by membrane
fragments from the ER, forming
autophagosomes. Both phagosomes and
autophagosomes fuse with lysosomes to
form large phagolysosomes, in which their
contents are digested.
Functions of Lysosomes:

12. Endoplasmic reticulum (ER):
It was discovered in 1945 by Albert Claude in Belgium. The endoplasmic reticulum (ER)
is important in the production or synthesis of cell components. Endoplasmic reticulum is
a network of channels present throughout the cell.
This Network of interconnected channels extending and often continuous with cell
membrane to nuclear membrane is called Endoplasmic reticulum. They contain
Cisternae which are spherical or tubular membranes which separates the material
present in these channels from cytoplasmic material.
Endoplasmic reticulum is divided into two types i.e.
1- Smooth ER= One without ribosomes.
2- Rough ER= One with ribosomes attached to external surface.
Some important functions of ER are:
MECHANICAL SUPPORT, TRANSPORT OF MATERIAL,
SYNTHESIS OF PROTEIN, STROAGE OF COMPOUND

13. Smooth Endoplasmic reticulum (ER)
SER is more tubular then RER and forms a
separate interconnecting network. (Is found
evenly distributed among the Cytoplasm). SER
has no ribosomes on it.
Smooth ER manufactures lipids and in some
cases the metabolism of them and associated
products. The smooth ER also controls
calcium level in the muscles and detoxifies
poisons, alcohol, and drugs.
Rough Endoplasmic reticulum (ER):
The RER is dotted with ribosomes. (Which is why it is called “rough”). The RER is
involved with protein production, protein folding, quality control and dispatch.
The RER is involved with the synthesis of proteins. They produce and process specific
proteins at ribosomal sites. Consists of network-like tunnels with tubules, vesicles and
cisternae which is held together by the cytoskeleton of the cell.

14. PEROXISOMES:
Peroxisomes are organelles found in nearly all
eukaryotic cells in 1967 by Christian De Duve. It is a cell
organelle that containing catalase , peroxidase , and other
oxidative enzymes and performing essential metabolic
functions, as decomposition of fatty acids (D-amino acids,
and polyamines) and peroxide.
These are single-membrane structures found in all
eukaryotic cells. They are small, membrane-bound
structures that use molecular oxygen to oxidize organic
molecules. The structure is one of the major oxygen
utilizing organelles, the other being the mitochondria.
Peroxisomes also break down uric acids and amino
acids. Peroxisomes contain more than 50 enzymes
including copious amounts of catalase.
Biologically they are used for the synthesis (of Glycerolipids, Glycerol ether Lipids,
Isoprenoids and Bile etc.) and Oxidation (D-amino acid, Uric acid to Allantoin, Hydroxy
acid to H2O2 etc). If Peroxisomes are not working properly it will cause Zellweger
Syndrome in which accumulation of long chain fatty acids in brain take place and
decrease the formation of plasmalogens and defect of bile acid formation.

15. VACUOLE:
A vacuole is a single membrane-bound organelle which is present in
all plant and fungal cells and some protists, animal and bacterial cells. Vacuoles are
formed by the fusion of multiple membrane vesicles .
FUNCTIONS:
Isolate materials that might be harmful or a
threat to the cell containing waste products
containing water in plant cells maintaining
internal hydrostatic
pressure or turgor within the cell.
Maintaining an acidic internal pH Containing
small molecules. Exporting unwanted
substances from the cell.

16. Nucleus and its History:
Nucleus was first reported in 1831 by Robert Brown .It control the life and
activities of the cell. In animal cells, it generally occupies the central
space, while in case of plant cells it is pushed towards periphery due to
presence of a large vacuole .
Nucleus is the most prominent and the largest cellular organelle. It has diameter of 10 μ
to 22 μ and occupies about 10% of total volume of the cell. Generally, the nucleus is
located in the center of the cell. It is mostly spherical in shape. However, the shape and
situation of nucleus vary in some cells. Nucleus is present in all the cells in the body
except the red blood cells (no nucleus). The cells with nucleus are called eukaryotes
and those without nucleus are known as prokaryotes. Presence of nucleus is necessary
for cell division. Most of the cells have only one nucleus (uni-nucleated cells). Few
types of cells like skeletal muscle cells have many nuclei (multi-nucleated cells).

17. Nucleus is covered by a membrane called nuclear
membrane and contains many components. Major
components of nucleus are nucleoplasm,
chromatin and nucleolus.
1- Nuclear Membrane: Nuclear membrane is
double layered and porous in nature. This allows the
nucleoplasm to communicate with the cytoplasm.
2- Nucleoplasm: Nucleoplasm is a highly viscous
fluid that forms the ground substance of the nucleus.
It is similar to cytoplasm present outside the nucleus.
Nucleoplasm surrounds chromatin and nucleolus.
STRUCTURE:
3- Chromatin: Chromatin is a thread-like material made up of large molecules of DNA.
The DNA molecules are compactly packed with the help of a specialized basic protein
called histone. So, chromatin is referred as DNA-histone complex.
4- Nucleolus: Nucleolus is a small, round granular structure of the nucleus. Each
nucleus contains one or more nucleoli. The nucleolus contains RNA and some proteins,
which are similar to those found in ribosomes.

18. Composition of Nucleus:
The nucleus contains deoxyribonucleic acid, or DNA, which is the genetic material of
life. Messenger ribonucleic acid, or RNA, is also important, as is makes a "negative"
copy (like the negative of a photograph) of the DNA and takes this information outside
the nucleus to the ribosomes. At the ribosomes, transfer RNA "translates" the code from
the messenger RNA, allowing the ribosomes to form protein.
It Control of all the cell activities that include metabolism, protein synthesis, growth
and reproduction (cell division), Synthesis of RNA, Formation of subunits of
ribosomes, Sending genetic instruction to the cytoplasm for protein synthesis through
messenger RNA (mRNA), Control of the cell division through genes, Storage of
hereditary information (in genes) and transformation of this information from one
generation of the species to the next.
FUNCTIONS OF NUCLEUS:

19. Mitochondria
Mitochondria is typically tubular or rod-shaped, double membrane bound organelles.
found in the cytoplasm of most eukaryotic cells. The word mitochondria is derived from
the Greek words μίτος (mitos) meaning “thread” and χονδρίον (chondrion) meaning
“granule”. The size of mitochondria is commonly between 0.75 and 3 μm in
diameter but vary in different cell. while the number of mitochondria varies in different
cells (liver cell more than 2000). Mitochondria is responsible for producing and supplying
most of the energy (Adenosine tri-phosphate-ATP) to the cell as it is called powerhouse
of the cell. Mitochondria are self-replicating organelles. Mitochondria is bound by two
membranes, Outer membrane and Inner membrane.
Outer membrane:
The Outer membrane encloses the entire organelle and is 60 to 75 angstroms (Å) thick.
It is a smooth membrane and is composed of equal amounts of phospholipids and
proteins. It has a large number of special proteins known as the porins. The Porins are
integral membrane proteins and they allow the movement of molecules (that are of 5000
Daltons or less in weight to pass through it). The outer membrane is freely permeable to
nutrient molecules, ions, energy molecules like the ATP and ADP molecules.

20. The inner membrane:
The inner membrane forms many infoldings called cristae. This folding help to increase
the surface area inside the organelle. The cristae and the proteins of the inner
membrane aids in the production of ATP molecules. The area of the inner membrane is
about five times larger than the outer membrane. The surface of cristae contains small
knob like structures called F1 Particles or oxysomes. These are suspended inside the
Matrix. The space enclosed by the inner membrane is called Matrix. The matrix contains
a mixture of hundreds of enzymes, coenzymes, ribosomes and DNA. so mitochondria
can synthesize their own proteins. Unlike the outer membrane, the inner membrane is
strictly permeable, it is permeable only to oxygen, ATP and it also helps in regulating
transfer of metabolites across the membrane.
Intermembrane space:
It is a space between the outer membrane and the inner membrane. It is also known as
perimitochondrial space. it has the same composition as that of the cell's cytoplasm.

21. Functions:
ATP Synthesis: The most important
function of the mitochondria is to produce
energy. In the presence of Oxygen(Aerobic
Respiration),Glucose is Oxidized to major
products Pyruvate, NADH and ATP. But
when Oxygen is limited, glycolytic products
will be metabolized by anaerobic
Metabolism, a process that is independent
of the mitochondria. 4 ATP molecules are
synthesized during Anaerobic Metabolism
While during Aerobic Respiration yield of
ATP molecules is 13-times higher.
Mitochondria help the cells to maintain proper concentration of calcium ions within the
compartments of the cell.
It help in building certain parts of blood and hormones like testosterone and estrogen.
The liver cells mitochondria have enzymes that detoxify ammonia.

22. Discovery of Golgi Body:
They were discovered by Italian physician Camillo Golgi in 1898. Golgi apparatus or
Golgi body or Golgi complex is a membrane-bound organelle, involved in the
processing of proteins. It is present in all the cells except red blood cells. Usually, each
cell has one Golgi apparatus. Some of the cells may have more than one Golgi
apparatus. Unicellular contain more than one Golgi Apparatus. The Golgi apparatus is
noticeable with both light and electron microscope . It is also called Golgi complex. It is
located in the cytoplasm next to the endoplasmic reticulum and near cell nucleus. The
Golgi apparatus is present In Eukaryotic cell and absent in Prokaryotic cell. A cell may
have large and small Golgi complex.
STRUCTURE:
Each Golgi apparatus consists of 5 to 8 flattened membranous sacs called the
Cisternae. The Cisternae with associated vesicles are called golgi apparatus or golgi
complex. It has three ends or faces, namely cis face, Medial and trans face. The cis
face is positioned near the endoplasmic reticulum. Reticular vesicles from endoplasmic
reticulum enter the Golgi apparatus through cis face. The trans face is situated near the
cell membrane. The processed substances make their exit from Golgi apparatus through
trans face. Convex side of stack >> forming [Cis] face.
Concave side of stack >> maturing [trans] face.

23. 1- PROCESSING OF MATERIALS Vesicles:
containing glycoproteins and lipids are transported
into Golgi apparatus. Here, the glycoproteins and
lipids are modified and processed.
2- PACKAGING OF MATERIALS: All the processed
materials are packed in the form of secretory
granules, secretory vesicles and lysosomes, which
are transported either out of the cell or to another
part of the cell. Because of this, Golgi apparatus is
called the ‘post office of the cell’.
3. LABELING AND DELIVERY OF MATERIALS: Finally, the Golgi apparatus sorts out
the processed and packed materials and labels them (such as phosphate group),
depending upon the chemical content for delivery (distribution) to their proper
destinations. Hence, the Golgi apparatus is called ‘shipping department of the
cell’.
Functions of Golgi apparatus:

24. Ribosomes:
Palade was the first person to study them in 1995. Cell containing tiny granular
structure known as ribosome. It functions as a micro-machine for making proteins.
The ribosome word is derived - 'ribo' from ribonucleic acid and 'somes' from the
Greek word 'soma' which means 'body'. Ribosomes found in both Prokaryotic and
Eukaryotic cells.
Ribosomes are small particles, present in large numbers in all the living cells. The
ribosomes link amino acids together in the order that is specified by the messenger RNA
molecules.
Ribosomes exist in 2 forms i.e. either dispersed in cytoplasm or attached with RER as
tiny granules. Ribosomes are composed of special Proteins and RNA.
The RNA present in ribosome is known Ribosomal RNA. Each ribosome is consist of
two sub- units. In eukaryotic cell larger sub-unit is 60s(s=Svedberg),while smaller sub-
unit is 40 S (Animal cell ribosome) While in prokaryotic cell the larger sub-unit is 50s
and smaller subunit is 30s.
Two sub-unit attachment with each other is controlled by Mg ions.

25. Ribosomes Diagram:
During protein synthesis ribosome play following
functions: The main functions of ribosmes are :
They assemble amino acids to form specific proteins,
proteins are essential to carry out cellular activities. The
process of production of proteins, the deoxyribonucleic
acid produces mRNA by the process of DNA
transcription. The proteins that are synthesized by the
ribosomes present in the cytoplasm are used in
the cytoplasm itself. The proteins produced by the bound
ribosomes are transported outside the cell. Ribosomes
translate the mRNA into specific protein. A group of
ribosomes attached to mRNA is known as Polysomes.
Ribosomes arrange amino acids in specific manner to
form polypeptide chain. Ribosome can join up amino
acids at the rate of 200 per minutes.
Function of Ribosomes:
Structure of Ribosome:
There are two subunits compose
of: 1- Protein 25-40%,
2- RNA 37-62%,
3- In an eukaryotic cell ribosome
consist of two subunits of 70S
and 40S and contain 78%
Protein.

26. Centrioles:
The centrioles are cylindrical shaped cellular
organelles. They are found in most of the eukaryotic cells.
The centrioles are made of groups of microtubules, these
microtubules are arranged in a pattern of 9+3. The pattern
of the microtubules for a ring of 9 microtubules known as
"triplets" and the microtubules are arranged at right
angles to one another. In animals cells, the centrioles help
the organizing and assembly of microtubules during the
process of cell division.
Structure of Centrioles:
Each of the centriole is made up of nine triplet fibers and a barrel-shaped
appearance. Centrioles are of two types: a mother centriole and the daughter
centriole are arranged at perpendicular angles to each other. These two are surrounded
by dense matrix called Pericentriolar material. The length of the centriole is about
1,500 to 1,800 Ã in diameter. The centriole internally shows a characteristic cart wheel
structure. The centrosome structure is made of lipids and proteins. However, it also
contains carbohydrates and nucleic acids.

27. Function of Centrioles
The centrioles perform following
functions as given below:
1. centrioles disengage and gives
rise to a new centriole.
2. forming the spindle.
3. orientation of the spindle.
4. chromosomes attachment.
5. segregation of chromosomes.
6. position of the nucleus.
7. produce flagella or cilia.
8. fiber of the tail of sperms.

28. Very Much ……..
The cytoskeleton is a network of fibers extending throughout the Cytoplasm. The
cytoskeleton organizes the structures and activities of the cell.
Cytoskeleton:
TYPES OF CYTOSKELETON FIBRES:
There are three main types of fibers in the cytoskeleton:
i. Microtubules ii. Microfilaments iii. Intermediate filaments.
1- Microtubule: the thickest fibers, are hollow rods about 25 microns in diameter.
Microtubule fibers are constructed of the globular protein, tubulin, and they grow or
shrink as more tubulin molecules are added or removed. They move chromosomes
during cell division. Another function is as tracks that guide motor proteins carrying
organelles to their destination. In many cells, microtubules grow out from a centrosome
near nucleus. These microtubules resist compression to the cell. In animal cells, the
centrosome has a pair of centrioles, each with nine triplets of microtubules arranged in
a ring. During cell division the centrioles replicate. Are the central structural supports in
cilia and flagella. Both can move unicellular and small multicellular organisms by
propelling water past the organism.

29. 2- Microfilaments:
The thinnest class of the cytoskeletal fibers, are solid rods of the globular protein actin.
An actin microfilament consists of a twisted double chain of actin subunits.
Microfilaments are designed to resist tension. With other proteins, they form a
three-dimensional network just inside the plasma membrane.
In muscle cells, thousands of actin
filaments are arranged parallel to
one another. Thicker filaments,
composed of a motor protein,
myosin, interdigitate with the
thinner actin fibers. Myosin
molecules walk along the actin
filament, pulling stacks of actin
fibers together and shortening
the cell.
In other cells, these actin-myosin aggregates are less organized but still cause localized
contraction. A contracting belt of microfilaments divides the cytoplasm of animals cells
during cell division.

30. 3- Intermediate filaments:
Intermediate in size at 8 - 12 nanometers, are specialized for bearing tension.
Intermediate filaments are built from a diverse class of subunits from a family of proteins
called keratins. Intermediate filaments are more permanent fixtures of the cytoskeleton
than are the other two classes.
They reinforce cell shape and fix organelle location.
FUNCTONS OF CYTOSKELETON: The cytoskeleton also plays a major role in cell
motility. This involves both changes in cell location and limited movements of parts of the
cell. The cytoskeleton interacts with motor proteins. In cilia and flagella motor proteins
pull components of the cytoskeleton to past each other. This is also true in muscle cells.