A Short ppt about Cell(the basic unit of life) By: Varun Satpute & Group

1. Karnataka Law Society’s
KLS Public
School

2. Science
Group
Activity
FA-2

3. Contents:-
Fundamental Unit of Life: Cell
What is a Cell?
Discovery of Cell
Contents of Cell:-
1. Plasma Membrane and Cell Wall
2. Nucleus
3. Cytoplasm
o Cell organelles:-
 Endoplasmic reticulum
• Smooth Endoplasmic Reticulum
• Rough Endoplasmic Reticulum

4.  Ribosomes
 Golgi Apparatus
 Lysosomes
 Mitochondria
 Plastids (plants Only)
 Vacuoles
 Centrioles (animals only)

5. Fundamental Unit of Life:
Cell

6. What is a Cell?
Our Earth is inhabited by different kinds of living
organisms, who look very different from each
other. These living organisms archaebacteria,
eubacteria, protista (amoeba,
chlamydomans), fungi, plants and animals.
The bodies of living organisms are made up of
microscopic units called cells. The cell has
same central position in biology as an atom in
physical sciences. The cell is basis structural
and functional unit of living organisms.

7. Discovery of Cell

8. While studying a thin slice of cork, Robert Hooke
saw that the cork resembled the structure of
honeycomb consisting of many little
compartments. Cork is a substance which is
obtained from the bark of a tree. This was in
the year 1665 when Hooke made this chance
discovery through a self designed microscope.
Robert Hooke called these boxes-cells. Cell in
Latin means “little room”. Robert Hooke’s
discovery was important, because it indicated
for the first time that living organisms
consisted of a number of smaller structures or
units.

9. Contents of Cell

10. Plasma Membrane and Cell wall
 The plasma membrane is a thin semi-permeable membrane that
surrounds the cytoplasm of a cell, enclosing its contents. Its
function is to protect the integrity of the interior of the cell by
allowing certain substances into the cell, while keeping other
substances out. It also serves as a base of attachment for the
cytoskeleton in some organisms and the cell wall in others. Thus the
cell membrane also serves to help support the cell and help
maintain its shape.
 The cell wall is the tough, usually flexible but sometimes fairly rigid
layer that surrounds some types of cells. It is located outside the
cell membrane and provides these cells with structural support and
protection, in addition to acting as a filtering mechanism. A major
function of the cell wall is to act as a pressure vessel, preventing
over-expansion when water enters the cell. Cell walls are found in
plants, bacteria, fungi, algae, and some Achaea. Animals and
protozoa do not have cell walls

13. Nucleus
 The nucleus is the headquarters of the cell. It regulates all cell activity. It consists
of a nuclear envelope, (the outer membrane) and nucleoplasm. In the
nucleoplasm you can see chromatin and the nucleolus.
 The nuclear envelope is a double membrane. Is has 4 phospholipid layers. It is also
has large pores through which materials pass back and forth.
 Within the nucleus are found chromatin and a structure called the nucleolus.
Chromatin is DNA in its active form. It consists of DNA looped around histone
proteins. The nucleolus is a knot of chromatin. It is the nucleolus that
manufactures Ribosomes
 The nucleus regulates all cell activity. It does this by controlling the enzymes
present. The chromatin is composed of DNA. DNA contains the information for the
production of proteins. This information is encoded in the 4 DNA bases. Adenine,
thymine, cytocine, and guanine. The specific sequence of these bases tells the cell
what order to put the amino acids.
There are three processes that enable the cell to manufacture protein:
Replication allows the nucleus to make exact copies of its DNA
Transcription allows the cell to make RNA working copies of its DNA
In translation the Messenger RNA is used to line up amino acids into a protein
molecule

15. Cytoplasm
 Cytoplasm is the inner content of the cell membrane which separates the cell
membrane from the nucleus. Some important features of cytoplasm are as
follows:
 It is composed of Cytosol, organelles and inclusions.
 Cytosol is the soft, sticky and semi-transparent fluid in which various cell
organelles are suspended.
 Cytoplasm is not a simple clear fluid. Rather, it is a complex viscous fluid that
contains 70% water. The remaining portion is made up of proteins, carbohydrates
and lipids.
 Cytoplasm is one of the most active parts of a cell. While it does not take part in
the cellular processes, it does host most of the metabolic reactions.
 It helps a cell to perform several vital functions by transporting essential nutrients
to the required destinations.
 One of the important components of the cytoplasm is the cytoskeleton.
Cytoskeleton is a network of proteins (microtubules and microfilaments) which
together form the skeleton of the cytoplasm. The cytoskeleton is responsible for
the shape and movement of a cell.

17. Cell Organelles
All eukaryotic and prokaryotic cells have within
them a variety of different structures called
organelles. Organelles are small and function
much like organs function in a large organism.
Some organelles are responsible for gathering cell
energy, others for controlling cell activities. Plant
cells have different organelles than animal cells
but also have many similar organelles. They all
have a large variety of sizes and functions and
make life possible.

18. 1.Endoplasmic Reticulum
 Endoplasmic reticulum , or ER , is an interconnected network of membranous
structures like tubules, vesicles, and cisternae . Cisternae are the flattened
disk-like membranous structures. Tubules are tubular in shape, while vesicles are
sac-like structures.
 There are two types of endoplasmic reticulum, namely smooth endoplasmic
reticulum (SER) and rough endoplasmic reticulum (RER) . When Ribosomes get
attached to the surface of smooth endoplasmic reticulum, it becomes rough
endoplasmic reticulum.
 Functions of smooth endoplasmic reticulum
• Smooth ER synthesizes fats and lipids.
• It also takes part in the metabolism of carbohydrates.
• It actively participates in drug detoxification.
• It maintains the calcium ion concentration in the cytosol.
 Functions of rough endoplasmic reticulum
• Most of the lysosomal proteins are produced in the rough ER.
• It transports proteins to various destinations like the plasma membrane.
• This is the major site of glycosylation (addition of carbohydrates in proteins).

20. 2.Ribosomes
 Ribosomes are a cell structure that makes protein. Protein is needed for
many cell functions such as repairing damage or directing chemical
processes. Ribosomes can be found floating within the cytoplasm or
attached to the endoplasmic reticulum.
 The location of the ribosomes in a cell determines what kind of protein it
makes. If the ribosomes are floating freely throughout the cell, it will make
proteins that will be utilized within the cell itself. When ribosomes are
attached to endoplasmic reticulum, it is referred to as rough endoplasmic
reticulum or rough ER. Proteins made on the rough ER are used for usage
inside the cell or outside the cell.
 Proteins are an essential part of all cells. Both eukaryotes and prokaryotes
require protein to function and carry out daily activities. For this reason,
ribosomes are extremely important for the survival of living things.

22. 3.Golgi Apparatus
 THE GOLGI APPARATUS (ALSO GOLGI BODY OR THE GOLGI COMPLEX) IS AN
ORGANELLE FOUND IN MOST EUKARYOTIC CELLS.IT WAS IDENTIFIED IN
1897 BY THE ITALIAN PHYSICIAN CAMILLO GOLGI .AFTER WHOM THE
GOLGI APPARATUS IS NAMED.
 THE GOLGI APPARATUS PROCESSES AND PACKAGES
MACROMOLECULES,SUCH AS PROTEINS AND LIPIDS, AFTER THEIR
SYNTHESIS AND BEFORE THEY MAKE THEIR WAY TO THEIR DESTINATION
;IT IS PARTICULARLY IMPORTANT IN THE PROCESSING OF PROTEINS FOR
SECRETION.THE GOLGI APPARATUS FORMS A PART OF THE CELLULAR
ENDOMEMBRANE SYSTEM.

24. 4.Lysosomes
Lysosomes are specialized cell organelles present in
the cytoplasm. These are commonly found in
animal cells but are also found in plant cells. It is
surrounded by a single unit membrane, which
encloses a dense stroma and a large vacuole,
which contains about 50 hydrolytic enzymes.
These enzymes can digest most of the biological
substances. Lysosomes exist in four forms, such
as primary lysosomes, secondary lysosomes,
residual bodies and autophagosomes.

26. 5.Mitochondria
 Mitochondria are the powerhouse of cells.
 Their whole purpose is to break down the molecules in ATP (cell food) so
the cell can have the energy it needs to live Mitochondria.
 Its length is 3 to 4 micrometer & its diameter is 0.5 to 1 micrometer.
 Most of the cellular respiration takes place in mitochondria.
 Mitochondria have tow membrane are as follows:
(i)Outer Membrane
(ii)Inner Membrane
The outer membrane & inner membrane is protect from Lipoprotein.
There is a space between the inner membrane & outer membrane
called, not surprisingly, inter membrane space.

27. (i)Outer Membrane:
a . The outer membrane covers the mitochondria.
b .The outer membrane of cell are semi permeable or smooth which
means that material can enter and leave the cell.
(ii)Inner Membrane:
a .The inner membrane of mitochondria are in folding or finger like folding.
These folds are called Cristae.
b .The electron transport system is a series of protein imbedded on the
cristae of mitochondria.
 Cristae:
a .These cristae are important because they make more surface area
where chemical reaction can take space.
b .The molecules & some of the enzymes responsible for making ATP are
located in & on the folds of these inner membrane.
 Matrix:
a .The area inside the cristae is called the matrix.
b .The matrix is a fluid that has water & proteins (enzymes) all mixed
together here 's where the rest of the enzymes that make ATP come from.
c . The Krebs cycle occurs in the matrix while electron takes place on the
cristae.

29. 6.Plastids
Cytoplasm of plant cell consists of discoidal, oval or spherical bodies called
Plastids. They are present in all plant except bacteria, fungi and blue green
algae. Plastids are living. They are formed a fresh but arise from minute
pre existing bodies called Protoplastids already present in embryonic cells.
They multiply in number by division. On the basis of colour plastids are of
three types i.e. Leucoplasts, chloroplasts and chromoplasts. One form of
plastids can change in to another as Leucoplasts. Change into chloroplasts
when the former are exposed to light for a prolonged period. Similarly
chloroplasts change into leucoplasts in the continued absence of light.
Similar changes take place in chromoplasts. In young fruit the leucoplasts
gradually change into chloroplasts which finally turn into chromoplasts as
the fruit ripens. Leucoplasts are white and occur in storage cells of roots
and underground stems. They convert sugar into starch. Chloroplasts are
green plastids bearing green pigment chlorophyll. Chromoplasts are
yellow, orange and red and are present in petals of flowers are fruits.

31. 7.Vacuoles
 A vacuole is usually found in all plant and fungal cells, as well as some cells of
protistas, animals, and bacteria. These membrane-bound structures are basically
just enclosed compartments that are filled with both inorganic and organic
molecules, along with water to support the organelle. Vacuoles may also contain
solutions of enzymes and occasionally solid particles that have been engulfed.
 There is no typical size or shape for a vacuole, they simply vary depending on what
the individual cell needs. They're formed by the fusion of several different vesicles.
 Vacuoles can serve a wide variety of functions in a cell, and their importance
depends on what role they play within the cell. Typically, their job includes
isolating harmful materials, storing waste products, storing valuable water in a
plant cell, helping maintain the pressure within a cell, balancing the pH of a cell,
exporting products out of the cell, and storing proteins for seed germination.
 Vacuoles also have much more involved roles to play in the cell, such as autophagy,
supporting biogenesis and degradation of various structures, and the lysis of
unwanted proteins. Scientists have even theorized that the vacuole plays a
significant part in destroying bacterial intruders or storing helpful bacteria.

32. vacuole

33. 8.Centrioles
 Every animal-like cell has two small organelles called
centrioles. They are there to help the cell when it comes
time to divide. They are put to work in both the process of
mitosis and the process of meiosis. You will usually find
them near the nucleus but they cannot be seen when the
cell is not dividing. Centrioles are made of Microtubules.
 A centriole is a small set of microtubules arranged in a
specific way. There are nine groups of microtubules. When
two centrioles are found next to each other, they are
usually at right angles. The centrioles are found in pairs and
move towards the poles (opposite ends) of the nucleus
when it is time for cell division. During division, you may
also see groups of threads attached to the centrioles. Those
threads are called the mitotic spindle.

35. By:-
Varun V. Satpute
Pavan Majalikar
Afnaan Sayed
Vinay Mansabdar
Pranit Patil