Biology Lecture Slide Week 2

1. CELL STRUCTURE
AND
FUNCTION OF ORGANELLES

2. IN THIS TOPIC
 Structure and functions :
 Cell wall
 Cell membrane
 Organelles
 Movement of molecules/substances
in and out of the cell

3. CELL WALL

4.  Outside the cell membrane
 In plant cell, prokaryotes, some protista and
fungi only.
 Components :
 middle lamella
 primary wall
 secondary wall
 Plasmodesmata

5.  Land plants :
 Cellulose
 Lignin
 Suberin
 Waxy
 Waterproof (some tissue)
 Functions :
 Cell shape
 Support and mechanical strength
 Prevent haemolysis
 „skin‟
 Carbohydrate store

6. CELL MEMBRANE

7.  Both in animal and plant cell
 Selective permeable
 Composed of :
 Proteins
 Glycoprotein
 Glycolipids
 Phospholipid
 Cholesterol and lipoprotein (a few)

8.  Fluid mosaic model
 Lipid bilayer
 Phospholipid
 Hydrophilic head (polar)
 Hydrophobic tail (non-polar)
 Embedded protein
 Embedded between layer
 Integral protein
 Peripheral protein (not embedded)
 Free movement within layer
 As carrier and channel protein
 Cholesterol
 Make phospholipid stay in position
 ‘Fluid’
 protein and lipid molecules able to shift and move laterally
 ‘Mosaic’
 the protein molecules form mosaic-like patterns when viewed from
the top.

10.  Functions of cell membrane
 Barrier
 Maintain internal environment of cell
 Communication between cell
 Markers to foreign materials
 Transportation
(Text book page 29)

11. ORGANELLES

12. 1. Nucleus
2. Endoplasmic reticulum
3. Golgi apparatus
4. Mitochondria
5. Lysosomes
6. Ribosomes
7. Chloroplasts
8. Centrioles
9. Vesicles

13. Nucleus

14. Nucleus
 ‘The Control Centre’
 Available in all eukaryotes excepts ;
 Sieve tube of phloem
 R_ _ _ _ oo _ _ _ l l

15. Components of nucleus
nuclear envelope
nucleoplasm
nucleolus
chromatin

16. Nuclear envelope
 Two outer membranes (lipid bilayers)
 Innermost surface has DNA attachment sites
Nuclear pore bilayer facing cytoplasm Nuclear envelope
bilayer facing
nucleoplasm

17. Nucleolus
 dark spot
 in the middle of the nucleus
 produce ribosomes
Functions :
 Store genetics material and information
 Site of cell division
 Produce RNA & DNA

18. Endoplasmic reticulum

19.  In animal cells, continuous with nuclear
membrane
 Extends throughout cytoplasm
 Two regions - rough and smooth
Rough ER Smooth ER

20.  Functions
ROUGH ER SMOOTH ER
Prominent in cells that manufacture
protein for export ; digestive
enzymes, hormones, structural
protein or antibodies
Necessary for steroid synthesis,
metabolism and detoxification of
substances in liver, phospholipid
synthesis and excitation-
contraction coupling in skeletal
muscle
With ribosome Without ribosome

21. Golgi body

22.  Puts finishing touches on proteins and
lipids that arrive from ER
 Packages finished material for shipment
to final destinations
 Material arrives and leaves in vesicles

24. Mitochondria

25. ATP-producing
powerhouses
(aerobic respiration)
Membranes form
two distinct
compartments
ATP-making
machinery
embedded in inner
mitochondrial
membrane

26. outer
compartment
inner
compartment
outer membrane inner membrane
repeated foldings
of inner membrane
(cristae)

27. Lysosomes

28.  a vesicle
 with enzymes
 digest biological macromolecules
 ER to Golgi body
 Autophagy
 Autolysis

30. Ribosomes

31.  Function as the site of mRNA translation
during protein synthesis
 Free-wheeling in cytoplasm / attached to ER
 TWO subunits ; small and large

33. Chloroplasts

34.  Site of photosynthesis

35. Centrioles

36.  Type of cytoskeleton (network of fiber)
 In mitosis; source of mitotic spindle
 Functions ;
 Organise the formation of spindle fiber
 Organise the formation of cilia and flagella (9+2 /
9+3)

38. vesicles

39.  a sac
 In cytoplasm
 Types ;
 Lysosome
 Peroxisome
 Shuttle vesicles
 Secretory vesicles
 Endocytosis vesicles
 Storage vesicles

40. ♫ ♪ Take 5 ♫ ♪

41. MOVEMENT OF
MOLECULES/SUBSTANCES
IN AND OUT OF THE CELL

42.  The movement of molecules are based on
concentration gradient
 Concentration gradient ;
 Means the number of molecules or ions in one
region is different than the number in another
region
 In the absence of other forces, a substance
moves from a region where it is more
concentrated to one where it‟s less
concentrated - “down” gradient

43. Passive transport
Active transport
Endocytosis
Exocytosis

44. PASSIVE TRANSPORT
 Does not require ATP
 High to low of concentration gradient
 Types ;
 Diffusion
 Osmosis
 Facilitated diffusion

45. Diffusion
 movement of molecules or ions down a
concentration gradient
 the molecules move using a natural
kinetic energy

47. what determines the rate of diffusion?

48. Steepness of concentration gradient
◦ Steeper gradient, faster diffusion
Molecular size
◦ Smaller molecules, faster diffusion
Temperature
◦ Higher temperature, faster diffusion
Surface area
◦ Higher surface area, faster diffusion

49. Molecules that diffuse through cell membranes
Oxygen – Non-polar so
diffuses very quickly.
Carbon dioxide – Polar
but very small so
diffuses quickly.
Water – Polar but also
very small so diffuses
quickly.

50. Simple Diffusion
small, nonpolar molecules
(ex. O2, CO2)
Polar molecules
(ex. Glucose, water)
ions
(ex. H+, Na+, K+)
LIPID-SOLUBLE WATER-SOLUBLE
LIPID-SOLUBLE

51. Facilitated diffusion
 movement of molecules or ions
 down a concentration gradient
 with the help of transport protein
 Types of transport protein ;
 Carrier protein
 Channel protein

52. glucose transporter
solute (glucose)
low
[ conc‟n] of
glucose outside
cell > inside
Glucose
binds
Protein change
shapeGlucose is exposed to fluid on the
other side of the membrane,
detaches, leaves channel

53. Osmosis
 Water movement
 across a partially permeable membrane
 from an area of high water potential (low
solute concentration) to an area of low
water potential (high solute
concentration)

54. Hypotonic
Solution
membrane permeable to
water but not to solutes
Hypertonic
Solution

55. Tonicity 2% sucrose
solution
distilled water
10%
sucrose
solution
2%
sucrose
solution
Hypotonic
Conditions
Hypertonic
Conditions
Isotonic
Conditions

56. Isotonic solution Hypotonic solution Hypertonic solution
H2O H2O
(1) Normal (2) Lysed
H2O
H2O H2O H2O
Animal
cell
Plant
cell
(4) Flaccid (5) Turgid (6) Shriveled
(plasmolyzed)
(3) Shriveled
Plasma
membrane
H2O
H2O

57. ACTIVE TRANSPORT
 Transport of molecule
 Low to high of concentration gradient
 require ATP
 Involves carrier protein

58. ATP
ADP
Pi
higher calcium
concentration
lower calcium concentration
Calcium
enter
tunnel
Calcium
pump
ATP
transfer a
phosphate
group
Shape
change –Ca
release
Shape
returns o its
resting
position

60. ENDOCYTOSIS
 Transport of macromolecules
 Involves formation of vesicle
 Into the cell
 Two types;
 Phagocytosis
 Pinocytosis

62. phagocytic
vesicle
edible
bacterium
amoeba
Phagocytosis

63.  Phagocytosis; “cellular eating”.
 In phagocytosis, the cell engulfs a particle by
extending pseudopodia around it and
packaging it in a large vacuole.
 The contents of the vacuole are digested
when the vacuole fuses with a lysosome.

64.  In pinocytosis; “cellular drinking”
 a cell creates a vesicle around a droplet of
extracellular fluid.

65. EXOCYTOSIS
 Transport of molecules
 Out of a cell
 Enclosed in vesicle
 Move to cell surface membrane
 Fuse
 release

67. Both diffusion and facilitated diffusion are forms of passive transport of molecules
down their concentration gradient, while active transport requires an investment of
energy to move molecules against their concentration gradient.

68. Sekian
&
terima kasih