Class 9 Biology Chapter 6

1. THE FUNDAMENTAL UNIT OF
LIFE:CELL
CLASS IX

2. Cells
 Smallest living unit
 Most are microscopic

3. Discovery of Cells
 Robert Hooke (1665)
 Observed sliver of cork
 Saw “row of empty boxes”
 Coined the term cell

4. Cell theory
 (1839)Theodor Schwann & Matthias Schleiden
“ all living things are made of cells”
 (1855) Rudolf Virchow
“Omnis cellula e cellula ” all cells arise from pre-
existing cells

5. Principles of Cell Theory
 All living things are made of cells
 Smallest living unit of structure and
function of all organisms is the cell
 All cells arise from preexisting cells
(this principle discarded the idea of
spontaneous generation)

6. Cell Size

7. Cells Have Large Surface
Area-to-Volume Ratio

8. Characteristics of All Cells
 A surrounding membrane
 Protoplasm – cell contents in thick fluid
 Organelles – structures for cell function
 Control center with DNA

9. Cell Types
 Prokaryotic
 Eukaryotic

10. Prokaryotic Cells
 First cell type on earth
 Cell type of Bacteria and Archaea

11. Prokaryotic Cells
 No membrane bound nucleus
 Nucleoid = region of DNA concentration
 Organelles not bound by membranes

12. Eukaryotic Cells
 Nucleus bound by membrane
 Include fungi, protists, plant, and
animal cells
 Possess many organelles
Protozoan

14. THE UNIVERSE INSIDE OUR
CELLS
 Zoom into your own body to see the
different cells that make up your
heart, brain and bones.
 These trillions building block of cells
are communicating with each other
every moment of our lives.
 As the house is made by BRICKS.

16. ANIMAL CELL

17. PLANT CELL

19. CELL ORGANELLES
 The cellular components are called the Cell
Organelles.
 These cell organelles are membrane-bound,
present within the cells and are distinct in their
structures and functions.
 They coordinate with their functions efficiently
for the normal functioning of the cell.
 There are various organelles present within
the cell and are classified into three categories
based on the presence or absence of
membrane.

20. TYPES OF CELL
ORGANELLES
 Organelles without membrane: The Cell wall,
Ribosomes, Centrosome and Cytoskeleton are
without membrane-bound cell organelles.
 Single membrane-bound organelles: Vacuole,
Lysosome, Golgi Apparatus, Endoplasmic
Reticulum are single membrane-bound organelles
present only in a eukaryotic cell.
 Double membrane-bound
organelles: Mitochondria and chloroplast are
double membrane-bound organelles present only
in a eukaryotic cell.

21. CELL ORGANELLES

22. Movement Across the Plasma Membrane
 A few molecules move freely
 Water, Carbon dioxide, Ammonia, Oxygen
 Carrier proteins transport some molecules
 Proteins embedded in lipid bilayer
 Fluid mosaic model – describes fluid nature of a
lipid bilayer with proteins

24. Membrane Proteins
1. Channels or transporters
 Move molecules in one direction
2. Receptors
 Recognize certain chemicals

25. Membrane Proteins
3. Glycoproteins
 Identify cell type
4. Enzymes
 Catalyze production of substances

26. CELL MEMBRANE FUNCTION
 Passive Transport
 Active Transport
 Endocytosis
(phagocytosis & pinocytosis)
 Exocytosis

27. Passive Transport
 No energy required
 Move due to gradient
 differences in concentration, pressure, charge
 Move to equalize gradient
 High moves toward low

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

29. Diffusion
 Molecules move to equalize concentration

30. Osmosis
 Special form of diffusion
 Fluid flows from lower solute concentration
 Often involves movement of water
 Into cell
 Out of cell

31. Solution Differences & Cells
 solvent + solute = solution
 Hypotonic
 Solutes in cell more than outside
 Outside solvent will flow into cell And
cell will swell
 Isotonic
 Solutes equal inside & out of cell no
transport
 Hypertonic
 Solutes greater outside cell
 Fluid will flow out and shrink

33. 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

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

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

36. Endocytosis
 Movement of large material
 Particles
 Organisms
 Large molecules
 Movement is into cells
 Types of endocytosis
 bulk-phase (nonspecific)
 receptor-mediated (specific)

37. Process of Endocytosis
 Plasma membrane surrounds material
 Edges of membrane meet
 Membranes fuse to form vesicle

38. Forms of Endocytosis
 Phagocytosis – cell eating
 Pinocytosis – cell drinking

39. Exocytosis
 Reverse of endocytosis
 Cell discharges material

40. Exocytosis
 Vesicle moves to cell surface
 Membrane of vesicle fuses
 Materials expelled

41. Cell Walls
 Found in plants, fungi, & many protists
 Surrounds plasma membrane

42. Cell Wall Differences
 Plants – mostly cellulose
 Fungi – contain chitin
 Bactria- Peptidoglycon or Murin

43. Cytoplasm
 Viscous fluid containing organelles
 components of cytoplasm
 Interconnected filaments & fibers
 Fluid = cytosol
 Organelles (not nucleus)
 storage substances

44. Centrioles
 Pairs of microtubular structures
 Play a role in cell division

45. DNA
 Hereditary material
 Chromosomes
 DNA
 Protiens
 Form for cell division
 Chromatin

46. Nucleolus
 Most cells have 2 or more
 Directs synthesis of RNA
 Forms ribosomes

47. Endoplasmic Reticulum
 Helps move substances within cells
 Network of interconnected membranes
 Two types
 Rough endoplasmic reticulum
 Smooth endoplasmic reticulum

48. Rough Endoplasmic Reticulum
 Ribosomes attached to surface
 Manufacture protiens
 Not all ribosomes attached to rough ER
 May modify proteins from ribosomes

49. Smooth Endoplasmic Reticulum
 No attached ribosome
 Has enzymes that help build molecules
 Carbohydrates
 Lipids

50. Golgi Apparatus
 Involved in synthesis of plant cell wall
 Packaging & shipping station of cell

51. Golgi Apparatus Function
1. Molecules come in vesicles
2. Vesicles fuse with Golgi membrane
3. Molecules may be modified by Golgi

52. Golgi Apparatus Function
(Continued)
4. Molecules pinched-off in separate vesicle
5. Vesicle leaves Golgi apparatus
6. Vesicles may combine with plasma membrane
to secrete contents

54. Lysosomes
 Contain digestive enzymes
 Functions
 Aid in cell renewal
 Break down old cell parts
 Digests invaders

55. CELL ORGANELLES
1 NUCLEUS
2 GOLGI BODY
3 PLASMA MEMBRANE
4 CYTOPLASM
5 ENDOPLASMIC RETICULUM
6 MITOCHONDRIA
7 LYSOSOME
8 VACUOLES
9 RIBOSOMES
10 MICROBODIES
(a)PEROXIXOMES
(b)GLYOXYSOME
DISCOVERY
1 ROBERT BROWN(1831)
2 CAMEILLIO GOLGI
3 SCHWANN(1838)
4 STRASBURGER(1882)
5 PORTER(1943)AND NAMED
IN(1953)
6 ALTAMAN(1894)AND
NAMED BY BENDA(1897)
7 de DUVE(1955)
8 SPALLANZONI
9 ROBINSON AND BROWN
(1953) IN PLANT CELL AND
PALADE(1955) IN ANIMAL
CELL
10 RHODIN(1954)
(a)de DUVE(1965)
(b)BRIEDENBACH(1967)

57. End Chapter