basis of cell organelles for medical allied and first yr medical students

1. CELL ANG GENERAL PHYSIOLOGY
DR UJALA ALI
SENIOR LECTURER PHYSIOLOGY DEPARTMENT

4. CELL MEMBRANE

5. STRUCTURE O CELL MEMBRANE
 Lipids
Phospholipids
Sphingolipids
Cholesterol
 Protein
 Integral
 Peripheral
 Carbohydrate
 Proteoglycan
 Glycosaminoglycan

6. INTEGRAL PROTEINS
 Serve as receptors
Ligand-binding receptors
 Serve as adhesion molecules
To the surrounding extra-cellular matrix (integrins)
cell-cell adhesion molecules (cadherins)
 Carry out the transmembrane movement of water-soluble substances
pores, channels, carriers, pumps

7. PERIPHERAL PROTEINS
 Function as enzymes
 Participate in intracellular signaling
 Form a sub-membranous cytoskeleton
Ankyrin & Spectrin

8. Glycocalyx- The Membrane Carbohydrate
 Serve as self-identity markers
 Cell can recognize cell of its own type & join to form tissues
 Negative charge that repel other negative objects
 Act as receptor for binding hormones
 Immunity to infection → enable immune system to recognize and invade
invaders

9. CYTOPLASMIC COMPONENTS
 MEMBRANOUS ORGANELLES
 NON-MEMBRANOUS ORGANELLES
 CYTOSOL
 CYTOSKELETON

10. MEMBRANOUS ORGANELLES
 ENDOPLASMIC RETICULUM
 GOLGI COMPLEX
 LYSOSOMES
 PEROXISOMES
 MITOCHONDRIA

11. ENDOPLASMIC RETICULUM
 Endoplasmic matrix
Continuous with the space between the two membrane surfaces
of the nuclear membrane
 Types:
 Rough endoplasmic reticulum
 Smooth endoplasmic reticulum
Sarcoplasmic reticulum → A modified ER in skeletal & cardiac
muscles

12. SMOOTH ENDOPLASMIC RETICULUM
Lipid synthesis
Glycogen breakdown
Detoxification
Stores and releases calcium ions

13.  Rough endoplasmic reticulum
 Protein synthesis
 Initial folding of polypeptide chain with the formation of
disulphide bonds

14. GOLGI
COMPLEX

15. LYSOSOMES
 Bud off from Golgi apparatus
 Thickest lipid bilayer membrane among all organelles
 Contains about 40 different powerful hydrolytic enzymes
 hydrolytic enzymes :
 Hydrolytic enzymes split an organic compound
 By combining hydrogen with one part of the compound & the hydroxyl
portion with the other part of the compound

16. 1. Primary lysosome:
 Pinched off from golgi apparatus
 Inactive state
2. Secondary lysosome
 Active lysosome
 Formed by the fusion of a
primary lysosome with
phagosome or endosome

17. Functions o lysosomes
intracellular digestive system _
1. Ingested food particles
2. Unwanted matter _bacteria
3. Removal of excess secretory products from cell
4. Role in immunity
 destroy virus infected and tumor cells
5. Damaged cellular structures (autophagy)

19. PEROXISOMES
 Contain Oxidative enzymes and catalases
 Originated from self-replication or smooth endoplasmic reticulum
Functions:
1. Breakdown the fatty acids by beta-oxidation
2. Detoxification of toxic substances by oxidases

20. Oxidases use O2 and strip hydrogen from intracellular toxic
molecules(such as alcohol) and making them nontoxic
↓
O2 + Hydrogen Hydrogen peroxide (H2O2 )
↓
H2O2 Catalases H2O + O2

21. MITOCHONDRIA
 Power house of the cell
 Contains its own DNA (mtDNA)
 Descendants of bacteria that subsequently became permanent
organelles
 Contains enzyme complexes responsible for ATP production through
oxidative phosphorylation
 Self-replication

22.  Outer membrane
 Inner membrane →
folded in shelf-like inward
projections called cristae
 Mitochondrial matrix
 Intermembrane space

23. Role of ATP:
• Synthesis of new
chemical compounds
• Membrane transport
• Mechanical work

25.  Play a key role in programmed cell death , a process called
apoptosis
In condemned cell
↓
mitochondria become leaky
↓
cytochrome C leak out in the cytosol
↓
activates intracellular protein-cutting enzymes (CASPASES)
↓
systematically kill the cell from within

26. NUCLEUS
 Control center of the cell
 DNA genes
 Characteristics of proteins
 Intracellular enzymes
 Reproduction
 Nuclear membrane bilayer
 Nuclear pores 9mn
 Nucleoli
 No limiting membrane
 Enlarges during protein synthesis
 Store RNA

27. NON-MEMBRANOUS ORGANELLES
 RIBOSOMES
 VAULTS
 CENTROSOMES/CENTRIOLES

28. RIBOSOMES
 Types
1. Attached to RER
2. Free ribosomes
Structure: (composed of rRNA and ribosomal
proteins)
Large subunit
Small subunit

29. VAULTS
Three times as large as ribosomes
Shaped like octagonal barrels

30. Function of vault
Serve as cellular trucks for transport from nucleus to
cytoplasm
Nuclear pores are also octagonal and the same size as
vaults
↓
vaults would dock at or enter nuclear pores
↓
Pick up molecules synthesized in the nucleus(mRNA)
↓
and deliver their cargo elsewhere in the cell

31. CENTROSOMES/CENTRIOLES
 Located near the nucleus
 Consists of the centrioles
surrounded by an amorphous
mass of proteins
 Form and organize the
microtubule cytoskeleton

32. CYTOSOL
 ENZYMES
 TRANSPORT, SECRETORY AND ENDOCYTIC VESICLES
 INCLUSIONS

33. CYTOSKELETON
 MICROTUBULES
 MICROILAMENTS
 INTERMEDIATE ILAMENTS

34.  protein scaffolding dispersed throughout the cytosol
 “bone and muscle” of the cell
 by supporting and organizing the cell components
 controlling their movements

35. MICROTUBULES
 Long, slender, hollow tubes composed of
tubulin molecules
 Functions:
1. Maintain the structure and shape of the
cell
2. Movement of cilia and flagella
3. Form the mitotic spindle

36. 4. Transport of secretory
vesicles from one region of
the cell to
another(microtubular
highway)
• Molecular motors
• Kinesin, Dynein

37. MICROFILAMENTS
 Intertwined helical chains of actin molecules
 cellular muscles
 Functions:
 cellular contractile systems
muscle contraction and amoeboid movement
 Serve as a mechanical stiffener for microvilli

38. INTERMEDIATE FILAMENTS
 Help resist mechanical stress
 Neurofilaments:
 Found in nerve cell axon→ Strengthen &
stabilize it
 Keratin:
 found in skin and hair → gives it strength