2. Contents
 Introduction to cell
 History
 Number and cell size
 Cell type
 Structure of cell
 Cell membrane
 Cytoplasm
 Organelle in cytoplasm
 Nucleus
 Cell surface contact
 Molecule movement
 Endocytosis and Exocytosis
 References

3. Cell
 Cell-Structural and functional unit of
the living body.
 Smallest living unit
 Most of cells are
microscopic

4. Discovery of Cells
 Robert Hooke (Mid 1600)
 Coined term cell
 First seen cork plant cell
 (1889) Rudolf Virchow
“all cells come from cells”

5. Number
 Unicellular(consist of a single cell)
-Bacteria, Virus
 Multicellular – Human (Around 100 trillion
cells)
-Other animal
Amoeba proteus

6. Cell size
 Most of cell are between 5-50μm in
diameter
 Ex,RBC-7.5 μm
Columnar epithelial cells 20 μm tall
and 10 μm wide
 Larger cells
Skeletal muscle cell
Neurons

7. Can we see the cell

8. Cell Size

9. Cell Types
 Prokaryotic
 Eukaryotic

10. Prokaryotic cell
 First cell type on earth
 Cell type of Bacteria and Archaea
 No membrane bound nucleus
 Nucleoid = region of DNA concentration

11. Eukaryotic cell
 Organelles not bound by membranes
 Nucleus bound by membrane
 Fungi, Protists, Plant, and Animal cells
 Possess many organelles
Animal cell
Plant cell

14. Structure of cell
 Each cell is formed by cell body and
membrane
 Cell membrane –Separate cell body from
the surrounding cell
 Cell body -Cytoplasm
Nucleus

15. Cell membrane
 Protective sheath enveloping the cell body
 Separate intracellular and extracellular fluid
 Permits exchange of some substance
 Thickness- 75A to111A
 Double layer of
Phospholipids & Proteins

18. lipid layer
 Cell membrane-Bilayered component
 Lipids are cholesterols and phospholipids
 Phospholipids = Phosphrous and fatty acid
(Amino Phospholipid, Phosphetidyle Glycerol
Phosphetidyle Inositol)
Outer part- Hydrophilic
(soluble in water)
Inner part- Hydrophobic
(soluble in fat)

19. Significance of lipid layer
 Forms semi-permeable membrane
 Fat soluble substance can pass through it.
-O2, CO2 and alcohols
 Barrier to water soluble materials
-Glucose, Urea, Electrolytes

21. Protein layer
 Glycoprotein
 Two type
 Integral protein and peripheral protein

22. Significance of protein layer
 Integral proteins- Structural Integrity
Channels(formed by integral protein)
Diffusion of water soluble substance
Glucose, Electrolytes
 Receptors protein
Receptor for hormones and
neurotransmitter
Recognize certain chemicals
 Carrier protein
-Transport of substance(active or passive)
 Act as antigen
-act as antigen and provide antibody
formation

23. Significance of Membrane
Protein

24. Carbohydrate
 Attached to protein or lipid
 Significance- Negatively charged
-Glucocalyx of neighboring cell
help in tight fixation.
-Receptor for some hormone
-Contain specific antigen(RBC-blood group
antigen)

25. Cytoplasm
 Viscous fluid containing organelles
 Interconnected filaments & fibers
 Organelles
 Fluid= Cytosol
 Various particles
(Different shape and size)
-Proteins, Carbohydrate,
lipids and Electrolytes.
 200mg/ml of protein
 High K +
 low Ca+2 low Na+

26. Cytoskeleton
 Filaments & Fibers
 Made of 3 fiber types
◦ Microfilaments
◦ Microtubules
◦ Intermediate filaments
 3 functions:
◦ Mechanical support
◦ Anchor organelles
◦ Help move substances
Transport
Shape of cell
Actin and myosin
Shape of cell

27. A = actin, IF = intermediate filament, MT = microtubule

28. Organelle in Cytoplasm
 Organelle caries out various functions
 Two type-
 Bound by limiting membrane
Endoplasmic reticulum
Golgi apparatus
lysome, Peroxisome
Mitochondria
 Not bounded by limiting membrane
Chromosome, Ribosome
Microfilaments, Microtubules

29. Endoplasmic Reticulum
 Network of tubular and micrsomal
vesicular structure
 Outer side-Limiting Membrane
 Inner side- Endoplasmic Matrix(lumen)
 Helps to move substances within cells
Two types
◦ Rough endoplasmic reticulum
◦ Smooth endoplasmic reticulum

30. Rough endoplasmic reticulum
 Ribosomes are attached to surface
◦ Manufacture proteins
◦ Not all ribosomes attached to rough ER
 May modify proteins from ribosome
 Protein pass through membrane and
accumulate in cisternae.

31. Smooth Endoplasmic
Reticulum
 No attached ribosomes
 Various enzymes are present on outer
surface
 Enzymes- Metabolic process of cell

32. Smooth endoplasmic reticulum with associated vesicles
By courtesy of Rose Watson, Cancer Research UK.

33. Significance of Smooth Endoplasmic
Reticulum
 Carbohydrate metabolism
 Synthesis of non protein substance
◦ Cholesterol
◦ Steroid hormones
◦ Sebum
 Catabolism of toxic substance
 Cooperate with rough endoplasmic reticulum
and Golgi apparatus to synthesize new cell
membrane.
 Specialized type
In skeletal muscle-sarcoplasmic reticulum

34. Golgi Apparatus or Golgi
Body
 Present in all cell except Red Blood Cell
 Situated near nucleus
 Consist of 5 to 8 membranous sac
 The Sacs are flattened and called as
Cisternae

35. Function of Golgi Body
 Processing and delivering the protein
molecule to different parts of the cell.
Protein synthesized from endoplasmic reticulum
Transported in the form of Reticular Vesicle
To Golgi Body where it is processed and sorted out
Packed in the form of Secretory Granules, Secretory
Vesicles
Vesicles delivered by golgi body leave the cell
by exocytosis.
lysosomal Vesicles

37. Lysosomes
 Vesicular organelle
 80 to 800nm in diameter
 Have thickest covering membrane
 Many small granules present in lysosomes
 Contain digestive enzymes(hydrolytic
enzyme)
 More than 40 different type of hydroxylases
 All enzyme- lysozymes

38. Functions
◦ Digests protein, carbohydrate, Lipid,
nucleic acids
◦ Destruction of bacteria and other foreign
body.
◦ Removal of unwanted cell in embryo
◦ Break down old cell parts
◦ When bacteria enter into the cell
lysosomes rupture and immediately digest
the invaded bacteria or foreign body.

39. Lysosomal storage disease
 Enzymes are defective because of gene
 Materials that they normally degrade will
accumulate within late endosomes and lysosomes.
e.g. Tay-Sachs disease
 Hurler's Syndrome: Failure to metabolize certain
mucopolysaccharides causes the accumulation of
large amounts of matrix within connective
tissue, which distorts the growth of many parts of
the body.

40. Peroxisome
 Membrane limited vesicle
 Derived from endoplasmic reticulum
 Contain oxidative enzymes
 (Urate oxidase and D- aminoacid
oxidase)

41. Function of peroxisome
 Hydrogen peroxide is produced by
poisons or alcohol
(ethanol and formaldehyde)
 Peroxisome ruptures when hydrogen
peroxide is formed in cell.
 Oxidases destroys hydrogen peroxide
 Also destroy other enzymes necessary
for its production
 Gluconeogenesis from fats and
degradation of purine and fat.

42.  Zellweger syndrome
Genetic abnormality in peroxisome
biogenesis

43. Mitochondria
 Rod shaped, oval shaped structure
 Diameter - 0.5 to 1 μm
 Bilayered membranous organelle
Outer layer- Smooth
Inner layer- Series of shelf like projection
-Cristae
(provide large surface area)
 Contain RNA and DNA

44.  Principle source of chemical energy in
most of the cells
 Enzymes are located in mitochondrial
matrix and inner mitochondrial matrix.

45. Function
 Break down fuel molecules (cellular
respiration)
Glucose
Fatty acids
 Production of energy by catabolism of
digested food particles
 Stored in the form of ATP molecules
 So It is power house of cell
 Energy released by breakdown of ATP
molecule
When needed
 Mitochondria contain enzymes for citric acid

46.  Mitochondria are distributed within a cell
according to regional energy
requirements
-Near the base of cilia
-Near basal domain of cells of proximal
convulated tubules
-Proximal end of flagellum
 Genetic diseases of mitochondria affect
perticular tissues
Ex. Mitochondrial myopathies
Mitochondrial neuropathies

47. Ribosomes
 It is granular structure
 Diameter of 15 to 20 nm
 Contain 65%RNA and 35% Protein
 Some ribosomes remain free in
cytoplasm
Function of free ribosome
 Synthesis of protein from amino acid
 Synthesis of protein part of
hemoglobin
 Protein molecules of peroxisome

49. Nucleus
 Control center of cell
 3 to 10 μm in diameter
 Double membrane
(Nuclear membrane)
 Contains
◦ Nucleoplasm
◦ Nucleolus

50. Nuclear membrane
 Double layered, porous in nature
 Communicate with cytoplasm
 Outer layer continuous as endoplasmic
reticulum
 Inner space forms lumen of endoplasmic
reticulum
 Pores- Guarded by protein
- Diameter 80nm to 100nm

51. Nuclear envelope with nuclear pores

52. Nucleoplasm
 Gel like substance
 Contain DNA
 Called as
chromatin
 One or more in each nucleus
 Contain RNA and some proteins
 RNA synthesized by 5 pairs of
chromosome
 Condensed to form subunit of ribosome
 Subunit travel to cytoplasm through pore
 Fusion of subunits lead to formation of
Ribosome
Nucleol
i

53. Function of Nucleus
 Control center for all activity of cell
 It sends genetic information in the form
of DNA to cytoplasm for synthesis of
specific enzymes
 Enzymes are responsible for various
metabolic reactions.
 Genes present in the nucleus controls
cell division.
 The hereditary information is stored in
the nucleus and transferred from
one generation to next.

55. Cell surface contact
Two type
-General adhesive contact
calcium dependent
calcium independent
-Specialized contact

56. General adhesive contact
Calcium dependent adhesion molecule
Cadherins
selectins
Integrins
Calcium independent adhesion
molecule
Most are transmembrane proteins
N-CAMs
I-CAMs

57. Specialized Adhesive Contacts
Occluding Junction( Tight junction )
-Tight junction is made up of ridges
-Ridges have two halves which are in
close contact
- provide strength and stability
-prevent movement of ions and protein
Desmosomes
Hemidesmosomes

58. Communicating junction(gap junction)
 Cytoplasm of two cells is connected by
channels
 Diameter of channel 3 nm
 Passage of Ions, Glucose, Amino acid
 Rapid propagation of action potential
Connexon

59. Molecule Movement & Cells
 Passive Transport
 Active Transport
 Endocytosis
(phagocytosis & pinocytosis)
 Exocytosis

60. Passive Transport
 No energy required
 Move due to gradient
◦ differences in
concentration, pressure, charge
 Move to equalize gradient
◦ High concentration moves toward low
concentration.

61. Types of Passive Transport
1. Diffusion
2. Osmosis
3. Facilitated diffusion

62. Diffusion
 Molecules move to
equalize concentration
Osmosis
 Special form of diffusion
 Fluid flows from lower solute
concentration
 Often involves movement of water
◦ Into cell
◦ Out of cell

63. Solution Differences & Cells
Solvent + Solute = Solution
 Hypotonic
◦ Solutes in cell more than outside
◦ Outside solvent will flow into cell
 Isotonic
◦ Solutes equal inside & out of cell
 Hypertonic
◦ Solutes greater outside cell
◦ Fluid will flow out of cell

65. Facilitated Diffusion
 Differentially permeable membrane
 Channels (are specific) help molecule
or ions enter or leave the cell
 Channels usually are transport
proteins
(aquaporins facilitate the movement of
water)
 No energy is used

66. Process of Facilitated Transport
 Protein binds with molecule
 Shape of protein changes
 Molecule moves across membrane

67. Active Transport
 Molecular movement
 Requires energy (against gradient)
 Example is sodium-potassium pump

68. Endocytosis
 Movement of large material
◦ Particles
◦ Organisms
◦ Large molecules
 Movement is into the cells
Types of
 Endocytosis
◦ Bulk-phase (nonspecific)
◦ Receptor-mediated (specific)

69. Process of Endocytosis
 Plasma membrane surrounds material
 Edges of membrane meet together
 Membranes fuse to form vesicle

70. Exocytosis
 Reverse of endocytosis
 Cell discharges material

71. References
 Grey’s textbook of human anatomy
40th edition
 Guyton and Hall textbook of medical
physiology 12th edition
 Ganong’s textbook of medical physiology 21st
edition
 Human physiology volume-1,Dr. C.C
Chatterjee
 Text book of human histology, Inderbir singh
 http://www.biologymad.com/resources
 http://biology.about.com/od/molecularbiology
 http://rarediseases.about.com/od/raredisease
sz/a/030505.htm