This document provides information about cell structure and organization. It begins with an introduction to cell biology and discusses the historical figures who contributed to early microscopy and cell discoveries. It then outlines the key components of prokaryotic and eukaryotic cells, including cell membranes, nuclei, organelles, and other structures. The document concludes by summarizing the cell theory and some exceptions. Overall, the document serves as an overview of cellular components, history, and basic concepts in cell biology.

1. SMT. C.H.M College
DEPARTMENT OF BIOLOGY
Dr. Neelam Parab
Mr. Sunil Sharma
Mr. Rahul Badve
Mr. Sachin Sangare

2. Cell Structure
& Organisation

3.  The branch of biology which deals with
the study of structure, function,
molecular organisation, growth,
reproduction & genetics is called
Cytology/Cell Biology
 Simple microscope 50--100 times
 Compound microscope -- 1000 times &
more
 Electron microscope – 500000 times
 Cells have no specific/typical shape
(rectangular, circular, conical,
columnar)
Introduction

4. The Great Team
The term “Cell” was
introduced by Robert
Hooke
Anton van
Leeuwenhoek reported
other types of cells
J. E. Purkinje coined
the term Protoplasm.
Robert Brown
discovered & named
Nucleus
Historical Account

5. Historical Account
Robert Hooke's microscope
A reproduction of Anton
van Leeuwenhoek's
microscope from the 17th
century with a
magnification of 300x
Drawing of the structure of
cork by Robert Hooke that
appeared in Micrographia

6. Dimensions

7. Largest cell – Ostrich egg 15 cms.
Dimensions

8. Cell Theory/Cell Doctrine
 All organisms are made up of cells
 Cell is the basic structural &
functional unit of life
 Cells have genetic information & is passed from generation
to generation.
 Cells are similar in their chemical composition & metabolic
activity.
 All cells arise from pre-existing cells
 Cells are duplicating, self-contained units.

9. Exceptions to Cell Theory
 Viruses do not have cellular organisation
 Bacteria & BGA are prokaryotes, they do not show true
cellular structures
 Capacity of living nucleated cell, to differentiate into any
other type of cell & thus form a complete new organism.
TOTIPOTENCY

10. PROKARYOTIC CELL
NO Well Defined Nucleus
{NO WDN}
No Memb Bound cell Organelles
{NO MBO}

11. Pro – primitive Karyon – nucleus
Bacteria & Blue green algae constitute this group
There are four forms of bacteria
Spirilla– twisted
Cocci – spherical/ovoid
Vibrio – comma shaped
Bacilli – rodshaped
Prokaryotic Cell
Bacteria

12. Prokaryotic Cell
Blue green algae
(Cyanobacteria) are
photosynthetic prokaryotes.
They may be filamentous or
non filamentous
They fix atm. N2,
symbiotically or non
symbiotically
Blue green algae/Cyanobacteria

13. Prokaryotic Cell -- Components
Cell Envelope
Cytoplasm
Mesosomes
Chromatophores
Nucleoid/Genome Ribosomes
Inclusion bodies
Plasmids

14. Cell Envelope
It consists of three layers namely ;
GLYCOCALYX
Glycocalyx Cell wall
Plasma membrane
Outermost, made up of
macromolecules, help in
adhesion
Some have loose sheath
Slime, few have thick &
tough capsule.
Both the layers are made up
of polysaccharides & may
contain proteins
Glycocalyx

15. CELLWALL
Present below glycocalyx,
provides definite shape &
support.
Cellwalls of different bacteria show different types of
reactions with Gram’s Stain
 Made up of Peptidoglycans (Gram +ve) / Murein (Gram -ve)/ in
Eubacteria & Psuedo-peptidoglycan in Archaebacteria.
Cell Envelope

16. PLASMA MEMBRANE
Innermost covering made up
of Proteins & Lipids
Serves as barrier & helps in intercellular communication.
Bacterial plasma membrane is the site for photosynthesis,
respiration etc.
Membrane also holds receptor molecules to detect & respond
to chemicals.
Cell Envelope

17. No membrane bound nucleus, only long double stranded
circular DNA molecule
Highly coiled with the help of non histone proteins
Connected to plasma membrane through mesosome.
Nucleoid/Genome

18. Plasmids
Extra chromosomal, autonomously, self-replicating mini-
chromosomes
Render antibiotic resistance, fertility.
Used as an important tool in
Genetic engineering

19. Cytoplasm
Semi fluid ground substance or matrix.
Contains variety of inorganic & organic compounds.
Does not show cytoplasm streaming, lacks organelles.
Following membranous structures are seen
Mesosomes Chromatophores Inclusion bodies

20. Invaginations of plasma
membrane.
Forms vesicles, tubules,
lamellae.
 Involved in formation of
cell wall, DNA replication.
 Also involved in distribution of chromosomes to cells.
Exact function is still
unknown
Mesosomes

21. Usually seen in photosynthetic bacteria & BGA
They contain different
pigments such as;
Bacteriophaeophytin
Carotenoids
Bacteriochlorophylls
Chromatophores

22. Dense particles in the cytoplasm, made up of RNA & Proteins
Each 70s ribosome is made
up of two subunits 50s & 30s
Helps in protein synthesis
Termed as 70s ribosomes
S stands for Svedberg unit
(sedimentation in centrifuge
depending on speed & size of
particle).
Ribosomes

23. Storage granules lie freely in cytoplasm
They are of two types such as
Cyanophycean granules, Starch granules, Glycogen granules
Inorganic Inclusions
Organic Inclusions
Phosphates & Sulphur granules
Inclusion Bodies

25. EUKARYOTIC
CELL

26. Cell Wall
Protective, semi-transparent,
thick, strong, rigid
Made up of polysaccharides such as
Cellulose Pectin
Lignin Hemicellulose
Cutin
Suberin
Provides shape, helps in transport of material
Shows three layers namely
Primary cell wall – capable of
growth, seen in meristematic tissue,
mesophyll, pith.
Middle lamella – cementing substance
pectin, calcium and magnesium (ripening
is due to solubilization of pectin)
Secondary cell wall – thickens the wall, presence of pits, plasmodesmata
(cytoplasmic bridges)

27. Plasma Membrane/Cell membrane
Semi-permeable or selectively permeable
70 to 80 Ao in thickness,
structure explained by Singer
& Nicholson in Fluid Mosaic
Model
Different Proteins are
present in viscous fluid
matrix of phospholipid bi
layer so (trilaminar)
Each phospholipid bilayer
consists of Head & Tails
Head is hydrophillic & tail is hydrophobic
Lipid bilayer is 45 A o thick, tails at rightangles to the surface
Hydrophobic ends face each other, external surface has hydrophillic ends
Quasifluid nature of lipids renders fluidity and thus lateral movement of
proteins takes place

28. Plasma Membrane contd….
Proteins are globular, of 2 types
Extrinsic & Intrinsic
Extrinsic/Peripheral are
loosely held, intrinsic are
tightly bound also called as
Integral proteins.
 Some run across the entire
thickness & are called as
tunnel proteins
Tunnel proteins serve as a
passage for polar molecules
Transport of molecules across takes place passively, actively and osmosis
as well

29. Functions of Plasma Membrane
Imparts shape, protects
Regulates semi-permeability, reabsorption, excretion
& secretion.
Contributes in the formation of cell organelles
Many membranes serves as enzymes
Serves as a receptor of stimuli.
In amoeba it carries out locomotion, phagocytosis &
pinocytosis

30. Cytoplasm
Jelly like colloidal ground substance also called matrix
Outer ectoplasm, inner endoplasm
Shows streaming movements called CYCLOSIS
 Composed of sugars, amino acids, t-RNA, Nucleotides, minerals, vitamins,
proteins & enzymes.
 Also contains many organelles like nucleus, mitochondria.
 Source of raw materials and seat of metabolic activities
 As organelles like mitochondria and chloroplast have distinct functions
hence all other organelles are together termed as endomembrane
system.

31. CELL
ORGANELLES
Mitochondria
Endoplasmic Reticulum
Golgi apparatus
Plastids
Lysosomes
Sphaerosomes
Perioxisomes
Glyoxysomes
Ribosomes
Centrioles
Vacuoles

32. Mitochondria
Covered by lipo-proteinaceous double
membrane.
Polymorphic -- Rod shaped, filamentous,
small spherical, granular
0.2 to 2 micrometers, average number 50
to 50,000
Mitos – thread, Chondros -- granule
Also called as power house of cell as it
generated ATP
Inner membrane folded, selectively permeable
Outer membrane is smooth, permeable, 60 AO
Folds are called cristae, contain Oxysomes/F1 particles
Cavity is filled with dense homogenous, proteinaceous fluid called matrix
Matrix shows DNA, RNA, Proteins, Lipids, Ribosomes

33. Mitochondria contd….
ULTRASTRUCTURE
Head piece (100 AO),
Oxysomes show Head piece, stalk piece & Base piece
Stalk piece (32 AO)
Base piece(45 AO)

34. Mitochondria contd….
Electron Carrier molecules or Coenzymes are
present on the rest of the membrane.
They are the molecules of ATPase for
terminal step.
1 to 10 lacs of oxysomes are seen in a
mitochondrion
ULTRASTRUCTURE
Cytochromes
Electron carriers are as follows
Dehydrogenases Flavoproteins

35. Glucose (6C)
Pyruvic acid (3C)
NADH2 & FADH2
CO2 & H2O
Glycolysis
Cytoplasm
Kreb’s Cycle
Matrix
ETS
F1 particle
Steps in Respiration

37. Endoplasmic Reticulum
Tubules are irregular branches.
Cisternae are stacks of flattened parallel sacs.
Delicately branched & anastomosing network of
ULTRASTRUCTURE
Cisternae
Vesicles are circular, may be they form chains.
Tubules Vesicles
Each cisternae, tubule, vesicle is 50 to 60 AO in thickness
Diameter of the lumen is 400 – 700 AO filled with cytoplasm.
RER & SER are two types depending on presence or absence of ribosomes.
Cytoplasm inside the lumen is called Laminal & outside it is called
non-laminal.

38. Endoplasmic Reticulum contd…
Connected at one end with nuclear membrane
& the other with plasma membrane
Functions
Provide mechanical support to cytoplasm.
Helps in maintaining position of other organelles
Glycogen & lipids are synthesized & stored in ER.
SER plays role in detoxification of liver.
It also plays a role in synthesis & secretion of lipds.
Provides precursors to Golgi Complex.
RER – Protein Synthesis, associated Ribosomes are called protein factories
It also plays a role in synthesis steroid hormones by gonad & Adrenal cortex

39. Golgi Complex
Described by Camillo Golgi (nervous tissue)
ULTRASTRUCTURE
Aggregation of few to hundreds of
membrane bound bodiesMembranes are
smooth.
Membrane limited flattened saccules
or cisternae
Vesicles -- Large vacuoles filled with
amorphous substance
Made up of cisternae/lamellae, vesicles.
Lamellae/Cisternae are closely stacked, Commonly 2 to 8 in number
Around 50 lamellae are seen in liver cells

40. Plastids
Found in Algae, Plant cells & certain Protists
Semiautonomous having DNA, & double membrane
Leucoplasts
Chromoplasts
They are of three main types
Chloroplasts
No pigments
colourless,
Store food material
Amyloplast – starch
Elaioplast – oils
Aleuroplast – proteins
Coloured contains
pigments other than
chlorophyll Yellow, Orange,
Red in colour, found in flower
& fruits Green coloured
because of
chlorophyll

41. Chloroplast
ULTRASTRUCTURE
Polymorphic, covered by double
membrane peri-stromium, made up
of lipoproteins.
Outer and inner membrane encloses
peri-plastidil space.
Internally filled with homogenous
proteinaceous matrix -- stroma
Shows network of lamellae, namely;
grana & stroma lamellae
(Intergranal lamellae/fret channels)
Grana made up of thyllakoids, containing quantasomes, pigments for
photosynthesis.
Thyllakoids are membrane bound flattened sac like structures.
Plastidome – DNA molecule which makes chloroplast semiautonomous.

42. Lysosomes
Lysosomes are single lipo-proteinacious membrane
bound bodies
Lyso=digestive Soma=body
Elliptical or highly irregular in shape contain hydrolytic
enzymes hence called Suicidal Bags
Present in animal cells (except
mammalian RBC’s)
Avg. diameter – 0.25 to 0.8
micrometer, polymorphic
Lysosomes originate from “GERL”(Golgi associated ER)
Enzymes seen in a lysosome are
Acid Phophotases
Sulphatases
Proteases
Nucleases
Lipases
Glycosidases

43. Lysosomes contd…..
They are of four types
Primary lysosome
Secondary lysosome
Residual bodies
Autophagic vacuoles
Brings about loss of tail in tadpoles
Helps in digestion of food & foreign particles.
Helps in removal of carcinogens
Functions

44. Lysosomes contd…..
Small granules, homogenous contents
Inactive storage form or ready reserves of enzymes.
Formed by fusion of primary lysosome with endocytosis vacuoles
Larger bodies, heterogenous contents
Primary lysosome
Secondary lysosome/Heterophagic granules
Primary lysosome may fuse to an unwanted organelle to form a large sac
called as autophagic vacuole or auto-phagosome

45. Secondary lysosomes containing indigestible matter are called as residual
bodies.
Residual bodies
Lysosomes contd…..
Cells with diminished physiological activity require internal re-modelling
(intracellular digestion).
Excess organelles are eliminated by autophagy
In Dead cells the enzymes are released & thus the cells are digested.
In Sperms the enzyme Hyaluronidase dissolves the protective coat of
ovum.

46. Sphaerosomes – Storage & Synthesis of fats
Few other organelles
Perioxisomes – contains enzymes for synthesis of peroxides
Glyoxysomes – micro-bodies for oxidation of fatty acids
(germinating seeds)

47. Granular organelles not bound by
membrane
Ribosomes
Sites of Protein synthesis
Found attached to ER, also in
cytoplasm, mitochondrial matrix &
chloroplast.
150-250 AO in diameter, contain
RNA & proteins.
80S Ribosomes occur in groups and
are called as polysomes or
polyribosomes.
In groups they may be arranged
linearly or in rosette shaped cluster.

48. Membrane (semi permeable - tonoplast) bound fluid (cell sap) filled spaces are
called vacuoles.
Vacuoles
Alkaloids
They may contain Amino acids
Minerals  Esters
Tanins
 Waste products
Water soluble pigments - Anthocyanin
Prominently found in plants (2 -3 permanent
are seen), in animal cells few & smaller.
A single large vacuole occupying 90% of
cells volume called as central vacuole can
be seen.
Cell sap of vacuole is a store house of various ions & hence hypertonic
Some seeds store organic material like proteins in small vacuoles.
Maintains turgidity, excretion & osmoregulation
They store excretory products or compounds harmful or unpalatable to
herbivores.

49. Non membranous cylindrical or
rod-shaped micro-tubular structures
in animal cells
Centrioles
Nine clusters of 3 microtubules
arranged in circular pattern.
Help in spindle formation & basal
bodies of flagella.
Dense area of cytoplasm
containing radiating microtubules.
Centrosomes contain a pair of
cylindrical structures called as
centrioles.
Diameter – 1500 to 2500 AO
length – 1600 AO to 8 microns.

50. Cilia & Flagella
Fine hair like protoplasmic
outgrowths on free surface of cell.
Generate a current for transport of
materials & locomotion.
Cilia are small and many whereas
flagella is single and long.
They consist of basal body, basal
plate and shaft.
Basal body is placed in cytoplasm and derived from centriole.
It has nine peripheral triplets of fibrils (arranged like centriole)
Central tubule is covered by central sheath.
Shaft consists of sheath and axoneme, axoneme posesses 11 fibrils 9
peripheral doublets and two single central fibrils.
Sheath is connected to one of the tubule by radial spoke, central tubules
are connected to each other by bridges.
Peripheral doublets are connected through linkers/inter-doublet bridge.

51. Non living materials in vacuoles, cytoplasm or cellwall
Cell inclusions
They may be organic/inorganic in chemical composition.

52. Discovered by Robert Brown
Nucleus
Usually cells have single nucleus, in certain cases bi nucleated
(paramoecium), & multinucleated (fungi).
Prokaryotic cell shows only chromosome and is called as
nucleoid/Genome
Such cells are called Syncytial (animals) & Coenocytes (plants)
Position
Nucleus is placed centrally usually, variations are seen
Glandular cells – basal Adipose cells – peripheral

53. Nucleus contd…
Shape & Size
Depends on the shape of the cell
Columnar cells – Ovoid /elongated
Cuboidal cells -- Spherical
Squamous epithelial cells – disc shaped
WBC’s – bi/multilobed
Vorticella – “c” shaped
 Depends on volume of cell, amount of DNA & Proteins & metabolic
phase of cell

54. Nucleus contd…
It also consists nuclear pores, annuli, central granule & fibrous lamina.
Ideally a well defined nucleus shows following parts
Nuclear membrane Nucleoplasm Nucleolus
Nuclear pores Chromatin network
Nuclear membrane
Made up of two membranes, outer & inner with peri-nuclear space
 7-8 nm in thickness, outer communicates with ER & inner contains
dense material called fibrous lamina.

55. Nucleus contd…
Perinuclear Space
10-70 nm filled with fluid similar to ER.
Annuli
Nuclear pores are enclosed by electron dense rings/cylinders called as
annuli.
Nuclear pore + Annulus = Pore complex
Annuli work as diaphragm while pore complex works for selective
permeability
Central Granule
Not a constant feature

56. Nucleus contd…
Fibrous lamina
Honey comb pattern made up of acid protein
Functions of nuclear envelope
Separation of nuclear material from cytoplasm
Exchange of necessary materials
Attachment of organelles like ER
Synthesizes proteins
Source membrane for other membranes
Video......VideosXIIProtein Synthesis.mpg

57. Nucleus contd…
Transparent, semisolid, granular, acidophillic matrix called as nuclear
sap/nucleoplasm/karyolymph
Contains nucleic acids, proteins, enzymes & minerals.
Nucleoplasm
Nucleolus
Spherical acidophillic body
Active cells have large nucleolus,
Cells without synthetic activity may lack nucleolus
Dense homogenous body without limiting membrane
Coiled filament called nucleolonema in matrix
Amorphous matrix, chromatin, fibrils & granules

58. Nucleus contd…
Thread like coiled & much elongated structures
Stained by Feulgen stain heterochromatin & Euchromatin
Chromatin material
 Heterochromatin – dark, metabolically & genetically inert
Euchromatin – light, genetically active
Made up of nuleosomes, forms chromosomes

59. Nuclear
membrane
Nucleoplasm
Nucleolus
Chromatin
network
Nuclear pore
Eukaryotic Nucleus
well defined

60. Video