Robert Hooke discovered cells in 1665 using an early microscope. He observed the structures of cork cells. The development of electron microscopes in the 1930s allowed scientists to view cells and organelles at much higher magnifications. Key discoveries included the nucleus by Brown in 1831, living cells by Van Leeuwenhoek in 1674, and the proposal of the cell theory by Schleiden, Schwann, and Virchow from 1838-1858 stating that cells are the fundamental unit of life. Plant cells have additional structures like a cell wall and chloroplasts. The main components of plant cells are the cell membrane, cytoplasm, and nucleus. The nucleus contains DNA and controls the cell.

1. WELCOME

2. SCIENCE
HOLIDAY HOME
WORK
PLANT CELL

3. DISCOVERY OF CELL
Cell was first discovered by a great polymath or physicist --
ROBERT HOOKE

4. ROBERT HOOKE’S MICROSCOPE

5. HOOKE’S DRAWING OF CORK CELLS
(THESE ARE
DEAD CELLS
BECAUSE
HOOKE SAW
THESE CELLS
AFTER TAKING
A SMALL
PIECE OF THE
OUTER
COVERING OF
CORK TREE’S
STEM)

6. INVENTION OF ELECTRON MICROSCOPE
 The first electromagnetic lens was developed in 1926 by Hans Busch.
 German physicist Ernst Ruska and the electrical engineer Max
Knoll constructed the prototype electron microscope in 1931, capable of
four-hundred-power magnification; the apparatus was the first
demonstration of the principles of electron microscopy. Two years later, in
1933, Ruska built an electron microscope that exceeded the resolution
attainable with an optical (light) microscope. Five years later (1937), the
firm financed the work of Ernst Ruska and Bodo von Borries, and
employed Helmut Ruska (Ernst’s brother) to develop applications for the
microscope, especially with biological specimens. Also in 1937, Manfred
von Ardenne pioneered the scanning electron microscope. The
first practical electron microscope was constructed in 1938, at
the University of Toronto, by Eli Franklin Burton and students Cecil
Hall, James Hillier, and Albert Prebus; and Siemens produced the
first commercial transmission electron microscope (TEM) in 1939. Although
contemporary electron microscopes are capable of two million-power
magnification, as scientific instruments, they remain based upon
Ruska’s prototype.

7. ELECTRON MICROSCOPE
 An electron microscope is a
microscope that uses a beam of
accelerated electrons as a source of
illumination. As the wavelength of an
electron can be up to 100,000 times
shorter than that of visible
light photons, the electron microscope
has a higher resolving power than
alight microscope and can reveal the
structure of smaller objects.
 Electron microscopes are used to
investigate the ultrastructure of a wide
range of biological and inorganic
specimens including microorganisms,
cells,
large molecules, biopsy samples, met
als, and crystals.

9. DISCOVERY OF LIVING CELL
In the year 1674, with the help of
improved microscope Antonie van
Leeuwenhoek discovered the first living
cells in pond water for the first time.

10. LEEUWENHOE
K
(1632 – 1723)

11. DISCOVERY OF NUCLEUS
The nucleus was first described by Franz Bauer
in 1804 and in more detail in 1831 by Scottish
botanist Robert Brown in a talk at the Linnaean
Society of London. Brown was studying orchids
under microscope when he observed an opaque
area, which he called the "areola" or "nucleus", in
the cells of the flower's outer layer.

12. ROBERT BROWN
(1773 – 1858)

13. NUCLEUS

14. DISCOVERY OF PROTOPLASM
Dujardin in 1835 discovered the protoplasm and
named as “sarcode”.
Johannes E. Purkinje in 1839 first introduced the
term 'Protoplasm'.

15. FÉLIX
DUJARDIN
(1801 – 1860)

16. JOHANNES E.
PURKINJE
(1787 – 1869)

18. DEVELOPMENT OF CELL THEORY
1838 – Matthias Jakob Schleiden – stated all
plants composed of cells
1839 – Theodor Schwann – stated all animals
also composed of cells – thus claimed all living
things composed of cells and cell is the basic unit
of our life.
1858 – Rudolf Virchow – all cells come from
preexisting cells

19. DEVELOPERS OF CELL THEORY
Matthias
Jakob
Schleiden
1)

20. 2)
Theodor
Schwann

21. 3)
Rudolf
Virchow

22. CELL THOERY
All living organisms are composed of one or more
cells. (However, this is controversial because non-
cellular life such as viruses are disputed as a life
form.)
The cell is the basic unit of structure and
organization in organisms.
Cells come from pre-existing cells.

23. PLANT CELL

24. PLANT CELL STRUCTURE

25. THREE MAIN COMPONENTS OF ALL
CELLS
CELL MEMBRANE
CYTOPLASM
NUCLEUS

26. CELL MEMBRANE OR PLASMA MEMBRANE

27. PROPERTIES OF CELL MEMBRANE
Every cell is surrounded by a cell membrane.
It consists of lipids and proteins and small amount of
carbohydrates.
It is thin and elastic.
It is also called semi - permeable membrane or
selectively - permeable membrane because it is
selectively permeable to ions and organic molecules
and controls the movement of substances in and out
of cells.

28. FUNCTIONS OF CELL MEMBRANE
It gives form to the cell.
It maintains individuality of the cell.
It protects the cell from injury.
It keeps the cell contents in place and prevents their
mixing with the extra cellular materials.
It regulates the flow of selected substances in and out of
the cell.
It protects cell from its surroundings.

29. PLANT CELL WALL

30. PROPERTIES OF CELL WALL
It is thick and rigid.
It is non-living.
It is completely permeable.
It is composed of cellulose.
It provides structural strength.
The plant cell wall consists of three layers. Each layer
has its own unique structure and function.

31. FUNCTIONS OF CELL WALL
It is an additional protective wall present
outside the plasma membrane.
This is only present in plant cells,
bacterial cells and fungal cells.

32. CELL WALL VS CELL MEMBRANE

33. PLANT CELL NUCLEUS

34.  The word nucleus is derived from
a Latin word nucleus or nuculeus which means 'kernel'. Nucleus a
double-membrane bound cell organelle present in eukaryotic cells.
The nucleus constitutes most of the genetic material of the cell - the
DNA.
 The nucleus maintains the integrity of the genes which regulate the
gene expression, in-turn regulating the activities of the cell. Therefore,
the nucleus is known as the control centre of the cell.
 The nucleus is the largest organelle of the cell. The nucleus appears
to be dense, spherical organelle. It occupies about 10% of the total
volume of the cell.
 In mammalian cells the average diameter of the nucleus is
approximately 6 micrometres.
 A semi-fluid matrix nucleoplasm is seen inside the nucleus which is a
viscous fluid and is similar to the composition of the cytoplasm.
 It is also known as the brain of the cell.

35. NUCLEUR ENVELOPE
The nuclear envelope is also known as the nuclear membrane.
It is made up of two membranes the outer membrane and the
inner membrane.
The outer membrane of the nucleus is continuous with the
membrane of the rough endoplasmic reticulum.
The space between these layers is known as the perinuclear
space.
The nuclear envelope encloses the nucleus and separates the
genetic material of the cell from the cytoplasm of the cell.
 It also serves as a barrier to prevent passage of macro-
molecules freely between the nucleoplasm and the cytoplasm.

36. NUCLEAR PORE
The nuclear envelope is perforated with numerous pores called
nuclear pores.
The nuclear pores are composed of many proteins known as
nucleoproteins.
The nuclear pores regulate the passage of the molecules
between the nucleus and cytoplasm.
The pores allow the passage of molecules of only about 9nm
wide. The larger molecules are transferred through active
transport.
Molecules like of DNA and RNA are allowed into the nucleus.
But energy molecules (ATP), water and ions are permitted
freely.

37. CHROMOSOMES
 The nucleus of the cell contains majority of the cells genetic material in the
form of multiple linear DNA molecules.
 These DNA molecules are organized into structures called chromosomes.
 The DNA molecules are in complex with a large variety of proteins
(histones) which form the chromosome.
 In the cell they are organized in a DNA-protein complex known as
chromatin.
 During cell-division the chromatin forms well-defined chromosomes.
 The genes within the chromosomes consists of the cells nuclear genome.
 Mitochondria of the cell also contains a small fraction of genes.
 Human cells has nearly 6 feet of DNA, which is divided into 46 individual
molecules.

38. NUCLEOLUS
The nucleolus is not surrounded by a membrane, it is a
densely stained structure found in the nucleus.
The nucleoli are formed around the nuclear organizer
regions.
It synthesizes and assembles ribosomes and r RNA.
The number of nucleoli is different from species to
species but within a species the number is fixed.
During cell division, the nucleolus disappears.
Studies suggest that nucleolus may be involved in
cellular aging and senescence.

39. FUNCTIONS OF NUCLEUS
 It controls the heredity characteristics of an organism.
 It is responsible for protein synthesis, cell division, growth and
differentiation.
 Stores heredity material in the form of deoxy-ribonucleic acid (DNA)
strands.
 Also stores proteins and ribonucleic acid (RNA) in the nucleolus.
 It is a site for transcription process in which messenger RNA (m
RNA) are produced for protein synthesis.
 Aids in exchange of DNA and RNA (heredity materials) between the
nucleus and the rest of the cell.
 Nucleolus produces ribosomes and are known as protein factories.
 It also regulates the integrity of genes and gene expression.

40. PLANT CELL NUCLEUS
Plant cell nucleus is a double-membrane bound organelle.
It controls the activities of the cell and is known as the
master mind or the control centre of the cell.
The plant cell wall has two layers - the outer membrane
and the inner membrane, which encloses a tiny space
known as perinuclear space.
The nucleus communicates to the cell cytoplasm through
the nuclear pores present in the nuclear membrane. The
nuclear membrane is continuous with the endoplasmic
reticulum. The DNA is responsible for cell division, growth
and protein synthesis.

41. CYTOPLASM
Cytoplasm is a semi-fluid matrix
present between the nucleus and
cell membrane.
It contains many cell organelles.

42. ENDOPLASMIC RETICULUM

43. PROPERTIES OF ER
The endoplasmic reticulum is a network of membranes
found throughout the cell and connected to the nucleus.
The membranes are slightly different from cell to cell and
a cell’s function determines the size and structure of the
ER. For example, some cells, such as prokaryotes or red
blood cells, do not have an ER of any kind. Cells that
synthesize and release a lot of proteins would need a
large amount of ER.

44. SMOOTH AND ROUGH ENDOPLASMIC
RETICULUM
SMOOTH ENDOPLASMIC RETICULUM - Smooth ER
(SER) acts as a storage organelle. It is important in the
creation and storage of lipids and steroids. It has no
ribosomes.
ROUGH ENDOPLASMC RETICULUM - Rough ER (RER) is
very important in the synthesis and packaging of proteins.
Ribosomes are attached to the membrane of the ER,
making it “rough.” The RER is also attached to the nuclear
envelope that surrounds the nucleus. This direct connection
between the perinuclear space and the lumen of the ER
allows for the movement of molecules through both
membranes.

45. FUNCTIONS OF ER
Endoplasmic reticulum has a number of jobs within the
cell. This includes the folding and transport of various
proteins, specifically carrying them to the Golgi apparatus.
Some other proteins, mostly the glycoproteins, move
across the ER's membrane.
The ER is also responsible for marking these proteins that
it transports with a signal sequence. Other proteins are
headed outside the ER, so they are packed into transport
vesicles and moved out of the cell via the cytoskeleton.
Basically, the ER is the transportation system of the
eukaryotic cell, and its proteins are contained within it until
they are needed to move.

46. RIBOSOMES
Ribosomes minute particle consisting of RNA and
associated proteins found in large numbers in the
cytoplasm of living cells. They bind messenger
RNA and transfer RNA to synthesize polypeptides
and proteins.
Ribosomes can be found floating within the
cytoplasm or attached to the endoplasmic
reticulum.

47. FUNCTIONS OF RIBOSOMES
Cells need to make proteins. Enzymes made of
proteins are used to help speed up biological
processes. Other proteins support cell functions
and are found embedded in membranes. Proteins
even make up most of your hair. When a cell
needs to make proteins, it looks 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.

48. GOLGI APPARATUS

49. PROPERTIES OF GOLGI APPARATUS
The Golgi apparatus or Golgi complex is found in most
cells. It is another packaging organelle like
the endoplasmic reticulum (ER). It was named after
Camillo Golgi, an Italian biologist.
The Golgi apparatus is a series of membranes shaped
like pancakes. The single membrane is similar to the
cell membrane in that it has two layers. The membrane
surrounds an area of fluid where the complex molecules
(proteins, sugars, enzymes) are stored and changed.

50. FUNCTIONS OF GOLGI APPARATUS
The job of the Golgi apparatus is to process and bundle
macromolecules like proteins and lipids as they are
synthesized within the cell. The Golgi apparatus is
sometimes compared to a post office inside the cell
since one major function is to modify, sort, and package
proteins to be secreted.
The Golgi complex works closely with the rough ER.
When the ER makes a protein, a transition vesicle is
also made. It drifts through the cytoplasm to the Golgi
apparatus where it gets absorbed. After the Golgi works
on the molecules inside, it secretes a vesicle into the
cytoplasm which releases the protein molecule out of
the cell.

51. MITOCHONDRIA

52. PROPERTIES OF MITOCHONDRIA
Mitochondria are often referred to as the powerhouse of the cell.
They are small structures within a cell that are made up of two
membranes and a matrix. The membrane is where the chemical
reactions occur and the matrix is where the fluid is held.
Mitochondria are a part of eukaryotic cells.
Each cell contains a different number of mitochondria. The
number present is dependent upon how much energy the cell
requires. The more energy a cell needs the more mitochondria
that will be present. Cells have the ability to produce more
mitochondria as needed. They also can combine mitochondria
to make larger ones.
Mitochondria contains its own DNA and ribosomes. So, it can
make its self duplicates.

53. FUNCTIONS OF MITOCHONDRIA
The main job of mitochondria is to perform cellular
respiration. This means it takes in nutrients from the cell,
breaks it down, and turns it into energy. This energy is
then in turn used by the cell to carry out various
functions.
The energy is released in the form of ATP(Adenosine
triphosphate).
ATP is the energy currency of the cell.
It contains two membranes. Outer membrane is very
porous and inner membrane is deeply folded.

54. CHLOROPLAST

55. PROPERTIES OF CHLOROPLAST
Chloroplasts are the food producers of the cell. The
organelles are only found in plant cells and some protists
such as algae.
Two membranes contain and protect the inner parts of
the chloroplast. They are appropriately named
the outer and inner membranes. The inner membrane
surrounds the stroma and the grana (stacks
of thylakoids). One thylakoid stack is called a granum.

56. FUNCTIONS OF CHLOROPLAST
Chloroplasts work to convert light energy of the Sun into
sugars that can be used by cells. The entire process is
called photosynthesis and it all depends on the little
green chlorophyll molecules in each chloroplast.
Chlorophyll molecules sit on the surface of each
thylakoid and capture light energy from the Sun. As
energy rich molecules are created by the light-
dependent reactions, they move to the stroma where
carbon (C) can be fixed and sugars are synthesized.

57. VACUOLE
A vacuole is usually found in all plant and fungal cells.
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.

58. FUNCTIONS OF VACUOLE
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.

59. THANK YOU