description about cell biology, different types of cell organelles. single bound cell organellle and doubel membrane bound cell organelles, briefy explain different organelles inside the cell

1. Cell biology
Presented by
Shanti

2. Cell biology
• Definition: The branch of biology which deals with the
study of cell is called cell biology.
Cell: The basic structural and functional unit of life is
called cell.

3. Cell as unit of life
• The cell is basic structural and functional unit of life.
All the activities of multicellular organism depend upon
the activity of individual cell. All vital activities of
multicellular organism results the combined action of
these cells. But, in unicellular organism, all activities as
well as functioning depend upon different metabolic
activities of that cell.

4. History of cell
• Robert Hooke: First of all, study of cell was
done by Robert Hooke (1665). He studied thin
slice of cork under simple microscope and found
large number of hollow compartments like that
of honey comb. He called each compartment as
cell. He is known as father of cytology.
• Anton Von Leeuwenhoek (1675): He studied
bacteria, protozoans and blood cells under
microscope and found that cell is not a hollow
cavity but bears internal organisations. He is
known as father of bacteriology.
• Robert Brown(1831) described nucleus as a
spherical body.

5. Cell theory
• Two biologist M. Schleiden and T. Schwann in (1838)
formulated cell theory. They proposed that the cell is a
basic unit of life. But they were not able to explain how
new cells are formed. Later, Rudolf Virchow (1855)
explained that cells originate only from the pre-existing
cell by cell division.

6. Cell theory states that:
• Cell is the basic structural and functional
unit of life.
• All the living organisms are made up of cell.
• All the activities of multi-cellular organism
depend upon the activity of single cell.
• All the cells arise from pre-existing cell.
• Cell organelles can not survive without
cells.
• Life passes from one generation to other
generation in the form of living cell.
• Cell carries hereditary characters from one
generation to other.

7. Cellular Totipotency
• The ability of a plant cell to produce new plant is called
cellular totipotency. Each and every plant cell has a
capacity to produce a new plant. That potentiality of a
cell is called cellular totipotency. This concept was
given by Haberlandt (1902, German). It was
experimentally proved by Steward and his
co-workers(1950).

8. Steward’s experiment
• Steward and his co-workers (1950) took out few mature
phloem cells of root of carrot and cultured into a test
tube containing nutrient medium (carbohydrate,
minerals, vitamin, coconut milk). After few days an un-
differentiated mass of tissue is formed called callus. It
is transferred into semisolid nutrient medium of same
composition. Later callus differentiated in to root and
shoot and gives rise to plantlets.

10. Prokaryotic and eukaryotic
cells
• Prokaryotic cells: (pro- primitive; karyon-
nucleus) A cell which lacks well defined
nucleus and membrane bound cell
organelles is called prokaryotic cell. The
nuclear component DNA, RNA, Protein lie
freely in cytoplasm. Presence of naked DNA
i.e., not covered by histone protein. The
double membrane bound cytoplasmic
organelles like mitochondria, endoplasmic
reticulum, Golgi complex etc are absent.
Ribosomes are of 70s types. Mesosomes are
the site of respiration. The cell wall
consists of amino-sugars and amino-acids.
Absence of cellulose. Eg., Bacteria,
cyanobacteria, PPLOs (Pleuro-pneumonia
Like Organisms)

12. • Eukaryotic cells(Eu- well; Karyon- nucleated): A cell
which has well defined nucleus and membrane bound
cell organelles is called eukaryotic cell. It consists of
nuclear membrane, nucleolus, nucleoplasm. Ribosomes
are of 80s types. All double membrane bound
cytoplasmic organelles like golgi body, endoplasmic
reticulum, mitochondria etc. are present. DNA is
covered by histone protein.

15. Structure of cell
• Cell size: cells are varies in size. The
plant cell of Acetabularia (algae) is
about 10 cm in length. The egg cell of
ostrich is largest cell (135 x 170 cm;
15cm diameter), bacterial cell is
smallest ranges from o.1-0.01um. But
average size of cell is 0.1 to 0.01mm in
diameter.
• Shape: the cells are usually spherical,
oval, cylindrical, polyhedral,
rectangular and other several forms.

16. Cell wall
• The outermost, rigid, protective covering of cells of
plant, bacteria, fungi is called cell wall. It is absent in
animal cell. It is permeable in nature and provides
definite shape and rigidity to the cell. Based on
chemical composition, it has 3 layers: middle lamella,
primary wall and secondary wall.

17. • Middle lamella: It is common
cementing layer between two
adjacent cells. This layer is made up
of calcium pectate and magnesium
pectate. Softening of ripen fruits
and fibres are due to dissolution of
calcium pectate in middle lamella. It
is absent in meristematic tissues,
parenchyma, cortex, pith, fungi
bacteria, etc.
• Primary wall: It is found on either
side of middle lamella. It is made up
of cellulose, hemi-cellulose and
pectin substance. It is found in the
cells of fruits, cortex, pith etc.

18. • Secondary wall: It is thick layered situated just inner to
the primary wall. The formation of secondary wall
occurs in highly lignified mechanical cells like tracheids,
vessels, fibres etc. It bears cellulose, hemicellulose,
pectic and lignin substance. Some chemicals like
suberin, silica, wax, resin, etc are deposited in
secondary wall.

19. • Plasmodesmata: The cytoplasmic bridge present in the
cell wall of adjacent cell is called plasmodesmata. It
helps in the transfer of cytoplasmic material among the
adjacent cells.
• Pit: The depressed areas present in the secondary wall
of plant cell is called pit. It helps in rapid translocation
of materials between two adjacent cells.

22. Functions of cell wall
• It provide mechanical strength and definite
shape to the cell due to rigid cell wall.
• It protects the internal organelles of the cell.
• It protects the cell from attack of pathogen.
• Being permeable in nature, it helps in absorption
of water and minerals.
• Cutin, suberin, wax, and silica in the cell wall
reduce the rate of transpiration.
• Primary cell wall helps in expansion of cell.
• Plasmodesmata helps in transfer of cytoplasmic
material among the adjacent cells.
• Pits help in rapid translocation of materials
between two cells.
• Cell wall consists of many enzymes for metabolic
reactions.

23. Cell membrane
• It is thin, selectively permeable, elastic,
living outermost covering of the protoplast.
It is found just inner to the cell wall in
plant cell and outermost covering in animal
cell. It was named as cell membrane by
Nageli and Cramer in 1855.
Chemically it is made up of lipid,
protein and carbohydrates. Lipids are
present in two layers. Each lipid layer has
two ends called outer hydrophilic
end(head) and inner hydrophobic end(tail).
Outer hydrophilic end on both side is
covered by protein layer. Small chain of
carbohydrates are found attached with lipid
and protein molecules called glycolipid and
glycoprotein.

24. Functions of cell membrane
• Due to selectively permeable in nature, it allows
necessary material to enter inside cells.
• It protects the cell from mechanical injury.
• It consists of antigens which are beneficial for
separation of blood grouping, immune response.
• Microvilli are modified cell membranes that help
inn absorption of digested food material.
• It forms sheaths around cilia and flagella.
• Cell membrane of nerve cells helps in
transmission of nerve impulses.
• It helps in active transport of material.
• Enzymes of cell membrane are used in different
metabolic activities.

26. protoplasm
• The semi-fluid mass of cytoplasm including nucleus is
called protoplasm. It is also called physical basis of life.
The life is not possible without protoplasm. It consists
of 75-90% of water. It bears protein, lipid,
carbohydrates, essential inorganic mineral ions,
pigments, vitamins, growth hormones, enzymes etc.

27. Cytoplasm
• The semi fluid mass of protoplasm excluding nucleus is called cytoplasm.
It is found in between cell membrane and nuclear membrane. It consists
of organic compound (carbohydrates, lipid, protein, nucleic acid,
enzymes), inorganic compound(water, salt of sodium, potassium), cell
organelles, cytoplasmic inclusion, nucleus etc. Cytoplasmic matrix is
differentiate into outer gel(plasagel) and inner sol(Plasmasol).

28. Functions of cytoplasma
• It consists of a number of enzymes
for the synthesis of organic
molecules.
• It acts as medium for the transport
of various cellular products.
• It is the site of various metabolic
activities like respiration,
photosynthesis, protein synthesis.
• It acts as reaction medium.
• It helps in distribution of various
materials like nutrients,
metabolites, enzymes etc; inside the
cell.

29. Cell organelles
• The living sub-cellular membrane bounded structure of
cytoplasma is called cell organelles. These structures
have specific chemical composition, specific function
and definite structure. These are mitochondria,
plastids, endoplasmic reticulum, golgi body, lysosomes.
Vacuoles, microbodies, ribosomes, cilia and flagella and
nucleus.

30. Mitochondria
• Mitochondria are granular or filamentous
double membrane bounded cytoplasmic
organelles found in all eukaryotic cells.
They are also called as “power house of
cell” because they store and release energy
in the form of ATP during aerobic
respiration.
Mitochondria was first of all observed
by Kollikar(1880) but name mitochondria
was given by Benda(1898).
Mitochondria are the largest cell
organelles in animal cell. Normally they
have the length of 5-10mm and diameter of
0.5-2.omm.

31. structure
• The mitochondria is bounded by two
membranes i.e; outer membrane and inner
membrane. The space between two
membrane is filled with watery fluid. The
outer membrane is smooth but the inner
membrane is infolded inward forming finger
like projections called cristae. On the
membrane of cristae, large number of f1-
particles or oxysomes are found. Oxysomes
attached on the outer surface of cristae are
simple, sessile, but those on inner surface
have a head, stalk and basal body.
Oxysomes bear ATP synthetase enzymes.
• The matrix consists of dense granules, DNA
and ribosomes. Due to the presence of DNA,
mitochondria are also called as
semi-autonomous cell organelles.

32. Functions of mitochondria
• They are the site of ATP formation. So they are
known as power house of cell.
• They bear all the enzymes required for aerobic
respiration.
• They are involved in the oxidation of proteins and
fats.
• They help in the synthesis of protein due to the
presence of DNA, RNA and ribosomes.
• They help in the formation of haeme of haemoglobin.
• They regulate calcium ions inside the cells.
• Total mechanism of kreb’s cycle occurs inside the
mitochondria.
• They have self replicating capacity and can form
their own copies.
• They help in the formation of yolk of egg.
• They help in the formation of middle part of sperm.

35. Cristae with oxysomes

36. Plastids
• The double membrane bound cell
organelles having DNA that store and
synthesized carbohydrates, protein
and lipid is called plastids. They are
found in plant cells but absent in
prokaryotes and animal cells. First of
all , the term plastid was introduced
by Haeckel in 1866. The plastids are
classified into three types.
• Chloroplasts (green plastids)
• Chromoplasts (coloured plastids)
• Leucoplast (colourless plastids)

37. Chloroplasts
• The green plastids bounded by double layered
membrane is chloroplast that help in photosynthesis.
Chloroplasts are present in all green coloured
eukaryotic cells but absent in fungi and animal cells.
The shapes of chloroplast varies in different species. In
higher plants, generally it is discoid in shape. It is 4-10
um in length and about 2-4um in breadth. Each cell
contains about 20-40 chloroplasts.

38. • Internally it consists of stroma (matrix) and
large number of thylakoid.
Matrix is rich in photosynthetic enzymes
and site of dark reaction. It consists of 70s
ribosomes, DNA, RNA, enzymes, water,
minerals, protein, lipids etc.
In the matrix large number of
thylakoid run from one end to other end of
chloroplast. At certain place they bear
stack coin like structure called grana which
bears photosynthetic pigments
(chlorophylls, carotenoid). The thylakoid
lies outside the granum is called stroma
lamellae(intergrana lamellae).

41. Functions of chloroplasts
• Chloroplasts are the site of photosynthesis
called kitchen of the cell.
• All the important process of photosynthesis
i.e., light reaction and dark reaction occurs
within the chloroplast.
• It maintains O2- CO2 balance on biosphere
and prevent global warming.
• It helps to reduce CO2 concentration In
atmosphere.
• Only chloroplast helps in the absorption of
light energy from sun and convert it into
biological energy.
• O2 is evolved by photolysis of water.
• It helps in the production of ATP by
photophosphorylation.

42. Chromoplast
• The non-photosynthetic coloured plastids
which synthesize and store coloured
pigments(carotenoid, xanthophyll) is called
chromoplasts. There are more than 100
carotenoids for different coloures. They are
found in the petals of flowers, ripen fruits
etc. They are formed by the internal change
in chloroplast or leucoplasts.
They are bounded by double layered
membrane and bear matrix but without
thylakoid and grana. Chromoplasts are of
following types:
Phaeoplast (brown pigment)
Rhodoplast (red pigments)

43. Functions of chromoplasts
• They make flowers showy and attractive which invite
insects for pollination.
• They provide colour to many fruits for their dispersal.
• They are rich source of carotene required for the
formation of vitamin A.

44. Leucoplasts
• The colourless plastids found in the non
green parts of plants are called
leucoplasts. They are enclosed by
double layered membrane and contain
matrix (stoma). They contain few
lamellae. On exposure to sun light, they
change into chloroplasts. On the basis
of storage of food material, they are of
following types:
• Amyloplasts (that stores starch)
• Lipoplasts or elaioplasts ( that stores
oil)
• Aleuroplasts ( that stores protein)

45. Functions of leucoplasts
• Leucoplasts stores various kinds of food materials like
starch, protein, lipids.

46. Endoplasmic reticulum
• Endoplasmic reticulum are small
membrane bounded micro-tubular sac
like structure originate from outer
nuclear membrane and extend upto cell
membrane. It was first reported by
Porter in 1945. It is found in all
eukaryotic cells except RBC of
mammals.
• . Structurally, endoplasmic reticulum is
composed of three different types of
structures called cisternae or lamellae,
vesicles and tubules.

47. • Cisternae are long, flat,
un-branched membranous sacs like
tubules arranged in parallel rows.
Each tubules are 40- 50um in
diameter.
• Vesicles are normally round or ovoid
sacs. They are found freely in the
cytoplasm and pancreatic cells. They
range in diameter from 25-500 um.
• Tubules are branched, tube-like
structures with variable diameters
that varies from 50-100um in
diameter. It contains many enzymes,
lipids and other proteins.

50. Types of ER
• On the basis of presence or absence of ribosomes on the
surface, ER of two types:
• 1.Rough Endoplasmic Reticulum (RER) (Granular ER):
They bear ribosomes on their outer surface. It consists
of more cisternae. It lies closer to he nuclear membrane
and helps in protein synthesis and transport of protein
and nuclear material.

51. • 2. Smooth endoplasmic reticulum (SER) (Agranular
ER): They don’t bear ribosomes on their outer surface.
Mostly it consists of vesicles and tubules and lies closer
to plasma membrane. It take part in lipid synthesis. SER
are generally found in adipose cells, intestinal cells,
spermatocytes.

52. Functions of Endoplasmic
reticulum
• It provides mechanical support.
• Membrane of ER possess site for a number
of enzymes to carry out specific reactions.
• It conducts information from outside to
inside of the cell and between different
organelle of same cell.
• It helps in quick transport of nuclear
material.
• It forms vacuoles.
• During telophase, it helps in the formation
of nuclear membrane.
• It helps in synthesis of lipid, protein,
hormone.

53. Golgi body
• Golgi body is a complex living component of cell made
up of cisternae, tubules, vesicles and vacuoles that help
in secretion of complex bio-chemicals. It was first of all
studied by Camillo Golgi (1898), in brain cells of owl and
cat. It is found in all eukaryotic cells except the cells of
some fungi, RBC and sperm cells of Bryophytes and
Pteridophytes.

54. It is bounded by two membranes and is 1-3um in length and
0.5um in diameter. It consists of cisternae, tubules, vesicle
and vacuoles.
Cisternae: Cisternae are elongated, double layered, flat and
slightly curved parallel sacs with swollen ends. The convex
face of cisternae is called cis-face (forming face) while
concave face is called transface ( maturing face).
Tubules: These are short, branched, interconnected network
like filamentous structure developed at the end of
cisternae.
Vesicles: They are small sac like structure developed from
the tubules. They are of two types i.e., smooth and coated
vesicles. Smooth vesicles have smooth surface and contain
secretory product. Coated vesicles have rough surface.
They are found in convex face.
Vacuoles: They are large rounded vesicles developed on the
concave face of cisternae. They function as lysosomes.

55. Functions of Golgi Body
• Golgi body acts as secretary vesicles and secrete
complex biochemicals.
• During cell division, cell plate is formed by golgi
body.
• Vesicles get incorporated in cell membrane. So size
of cell membrane is increased.
• It helps in the secretion of mucus by intestinal cells,
; lactoprotein by mammary gland cells,; thyroxine
hormone by thyroid cells.
• It helps in the formation of melanin granules and
other pigments.
• Components of cell wall like pectin, hemicellulose,
microfibrils are synthesized by golgi body.
• It transports and chemically modifies of protein,
lipids, fat in cell etc. Thus it is known as “Principal
Director of Macro-molecular traffic in cell”.
• It helps in the formation of primary lysosomes.

58. Lysosomes
• Lysosomes are small single membrane
bound cytoplasmic organelles which contain
digestive or hydrolytic enzymes and help in
intracellular digestion. They are mostly
found in animal cells, but only few in plant
cells. They are developed from endoplasmic
reticulum and vesicles of golgi body.
• Under certain condition these lysosomes
may cause the digestion of other organelles
of the same cell which cause the death of
the cell. Due to their such activity they are
also called as “suicidal bag” or “autophasic
vacuole”.

59. Types of lysosomes
Lysosomes are of following types:
• Primary lysosomes: They are the
lysosomes containing hydrolytic
enzymes.
• Secondary lysosomes: They are the
lysosomes formed by the union of
primary lysosomes with vacuoles
containing food material.
• Residual body: They are the lysosomes
which bear undigested food particles.
• Autophasic vacuoles: These lysosomes
which digest other cell organelles of
same cells during scarcity of food.

61. FUNCTIONS OF LYSOSOMES
• Lysosomes digest the external food particles
like protein, lipid and glucose to provide
energy.
• Lysosomes help in extracellular digestion.
• They digest and damage the disease causing
micro-organism of the cell.
• Dead and worn out cells are digested by
lysosomes.
• Lysosomes initiate the process of mitosis.
• Leucocyte granules are derived from lyosomes.
• They take part in the synthesis of different
types of enzymes. Eg., thyroxine hormone
• In some cases, hydrolytic enzymes damage
tissues and break DNA and may cause several
disease including cancer.

62. Ribosomes
• Small, dense, rounded particle of ribonucleoprotein
is called ribosome. Robinson and brown reported
ribosomes in plant cell in 1953. These are found in
both prokaryotic and eukaryotic cells. It is found in
cytoplasm, matrix of mitochondria, and membrane
of endoplasmic reticulum.
Each ribosome contains two sub units of
unequal size. These sub units are attached together
by means of binding force of Mg-atom. On the basis
of size and sedimentation coefficient ribosomes are
of two types:
1. 70s ribosomes:- They bear two sub-units called
larger 50s and smaller 30s. These are found in
prokayotic cells as well as matrix of mitochondria
and chloroplast of eukaryotic cells.
2. 80s ribosomes:- They bear two sub-units called
larger 60s and smaller 40s. These are found in
cytoplasm of eukaryotic cells.

63. Functions of Ribosomes
• Ribosomes are the sites of protein
synthesis. So they are also called as
protein factories of cell.
• Free ribosomes synthesize enzymatic
protein.
• Genetic massage is transcribed from
DNA to mRNA.
• Genetic message is translated from
mRNA to protein.
• During protein synthesis many
ribosomes occur in a chain on
common mRNA strand called
polyribosomes or polysomes.

65. Nucleus
• A spherical dark staining protoplasmic
body of cell is called nucleus. It directs
and controls a all the cellular activities
and carries hereditary information and
also called as brain of the cell. It is
bounded by double layered membrane.
It was first all described by Robert
Brown(18310.
• It is found in all eukaryotic cells
except RBC, and some cells of
conducting tissues. It consists of 80%
protein, DNA, RNA, lipids and minerals.

66. • Well developed nucleus consists of
four parts i.e., nuclear membrane,
nucleoplasm, nucleolus and
chromatin fibres.
1. Nuclear membrane:- The double
layered porous covering of nucleus is
called nuclear membrane. It
separates the nucleus from
cytoplasm. It is made up of lipid and
protein. The outer membrane is
continuous with RER consisting
ribosomes. The nuclear pores help in
the exchange of substance between
nucleus and cytoplasm.

67. 2. Nucleoplasm:- The transparent, homogenous, semi-fluid
substance inside the nuclear membrane is called
nucleoplasm. It consists of water, lipid, nucleic
acid(DNA, RNA), proteins minerals, enzymes
(polymerase, endonuclease, helicase, etc). It consists of
nucleolus and chromatin fibres.

68. 3. Nucleolus:- The dark staining,
acidophilic, naked body present inside
the nucleus is called nucleolus. It
consists of RNA, and non-histone acidic
proteins.
Functions:
- It is ribosome factory.
- It helps in the formation of spindle
fibres during cell division.
- It helps in the formation of rRNA and
also stores RNA.
- It stores nucleoprotein.

69. • 4. Chromatin fibres:- Dark staining
elongated, coiled, thread like structure
inside the nucleus is called chromatin
fibres. It consists of DNA, RNA, histone and
non-histone proteins. It develops into
chromosomes during cell division. It
consists of two regions i.e.,
Heterochromatin and Euchromatin.
• Heterochromatin is dark stained and highly
coiled region of chromatid. It consists of
small amount of DNA and large amount of
RNA. Thus it is genetically inactive.
• Euchromatin:- Less stained and loosely
coiled region of chromatid is called
euchromatin. It consists of large amount of
DNA and thus it is genetically active.

70. Functions of nucleus
1. It passes genetic information from parents
to offsprings.
2. It controls all the cellular and metabolic
activities of cells.
3. It controls the synthesis of structural
protein and enzymatic proteins.
4. Nucleolus takes part in the formation of
ribosomes.
5. It helps in the formation of spindle fibres
during cell division.
6. It develops genetic variations which helps
in evolution.
7. DNA of the chromosome is the genetic
material.

71. Chromosomes
• Chromosomes are filamentous structure in
the nucleus formed by the condensation of
chromatin fibres during cell division. First
of all Strasburger(1875) observed the
chromosome, name chromosome was given
by Waldayer (1888).
It consists of DNA, RNA, histone and
non-histone proteins and metallic proteins.
Histone proteins are basic proteins and
contains amino-acids. Non-histone proteins
are acidic proteins (enzymes).
Chromosomes transmits hereditary
informations from parents to offsprings.

72. • Somatic cells have 2n number of
chromosomes, while the gametes have ‘n’
number of chromosomes. Complete sets of
haploid chromosomes are called genomes.
The number of chromosomes varies in
different organisms. Generally chromosomes
of plant cells are larger than that of animal
cells.
The length varies from 1-30um. The
largest chromosomes are polytene and
lampbrush chromosomes having length 2000u
and 5900um respectively. Each chromosome
consists of centromere. On the basis of
position of centromere chromosomes are of
following types:

73. 1. Telocentric: Centromere is found at the
tip.
2. Acrocentric: Centromere is found near the
tip.
3. Sub-metacentric: Centromere is found
near the centre.
4. Metacentric; Centromere is found at the
centre of chromosomes having equal arm.
Chromosome without centromere is
acentric. Chromosome with two
centromere is dicentric.

75. Structure of chromosomes
• Each chromosome consists of following parts:
1. Chromatids: Each chromosome at metaphase
stage consists of two strands called
chromatids. Thus chromatids are the half of
chromosomes.
2. Centromere: Chromatids are attached at a
narrow area called centromere. Spindle fibres
attached at centromere during metaphase.
3. Chromonemata: Thin and highly coiled
filaments seen during prophase is called
chromonemata.
4. Chromomere: The beaded like structures
along the entire length of chromatid are
called chromomere.

76. 5. Kinetochore; A disc-shaped protein
structure at the surface of centromere is
called kinetochore.
6. Telomere: terminal end of chromosome is
called telomere.
7. Secondary constriction: Any constriction in
chromosome other than centromere is
called secondary constriction.
8. Setellite: Rounded part of chromosome
beyond the secondary constriction is called
satellite. The chromosome having satellite
is called sat chromosome.
9. Nucleolar organizer: Some secondary
constriction contains gene Which codes for
rRNA is called nucleolar organizer.

78. Functions of chromosomes
1. It carries genetic information from one generation to
next generation.
2. It helps in the formation of mRNA.
3. It helps in the replication of DNA.
4. It controls the synthesis of structural proteins.
5. It helps in cell division and cell growth.
6. It helps in variation due to mutation.

79. Microfilament
• Long narrow, solid, cylindrical, electron
microscopic, proteinaceous structure
found in cytoplasm is called
microfilament. They are made up of
protein and found in the microvillus,
muscle fibres. They form network in
cytoplasm.
• Functions:
1. They give shape and mechanical
support to the cell.
2. Microfilaments of muscle help in
movement and locomotion.
3. Microfilaments of microvilli help in
absorption of food.
4. They help in cyclosis.

80. Micro tubules
• Narrow, long, unbranched, proteinaceous,
electromicroscopic, hollow tubes found in cytoplasm,
cilia, flagella is called microtubules.
Functions:
1. They form cytoskeleton for giving shape of cell and
mechanical support for cell organelles.
2. They help in cell movement.
3. They form spindle fibres during cell division.

81. Microbodies
• They are small cell organelles bounded by single
membrane filled with dense matrix. They are found in
some plant cells, fungi, liver and kidney cells,
unicellular eukaryotic cells. Yhey are of following types:
1. Peroxisomes: The microbodies containing enzymes for
hydrogen peroxide bio-synthesis is called peroxisomes.
H2+O2 Peroxiase H2O2 catalase 2H2O

82. 2. Glyoxysome: The microbodies containingthe enzymes
for fatty acid metabolism and gluconeogenesis(
conversion of lipid into carbohydrates in germinating
seeds) is called glyoxysome. It is found in germinating
seeds).
3. Sphaerosomes: The microbodies which take part in the
storage and synthesis of lipid is called sphaerosomes.

83. Cell inclusions
• The non living substances in the cell
are called cell inclusions. They are
also called ergasic bodies. They are
of three types:
1. Reserve food material
2. Excretory products
3. Secretory products
1. Reserve food materials: Some
important reserve food materials
includes carbohydrates, nitrogenous
substances and fats.

84. • Carbohydrates: Carbohydrates are
important storage food material of
cell. They are found in different
forms i.e., starch, glucose, fructose,
sucrose, cellulose, hemicellulose,
pectin, chitin glycogen etc.
• Nitrogenous substances: These
includes proteins and aminoacids.
• Fat and oils: These are found in the
cytoplasm. Fats are present in
animal cells but the oils are
commonly present in seeds and fruits
of plants.

85. 2. Excretory products: They are the by-products of plant
metabolism. They are not used by plants. The common
excretory products includes alkaloids, gum, resins,
tannins, essential oils, latex, mineral crystals.
3. Secretory products: These materials are secreted by
protoplasm of cell and are useful to the same body. Eg.,
Nectar, Anthocyanin, hormones.