1. The Cell Lecture NO: 1st MBBS
Dr Muhammad Ramzan

2. Cell- the definition
Cell is the basic structural, functional and biological unit of all known living organisms except viruses
Enclosed by a semi permeable membrane and includes nucleus/organelle
Human body have 100 trillion cells
– webster.com

3. Have genetic information and can replicate itself
Cell – the background
Have genetic information and can replicate  itself
Is covered by a semi permeable membrane enclosing cytoplasm and cell organelle
Can utilize nutrients for energy production
Excretes waste products
The study of cells is called cell biology.
- online.org -

4. Parts of a Cell
Cells have 4 different parts, each with a different function
These parts are :
1. Cell membrane -
2. Cytoplasm
3. Cytoskeleton and
4. Cell organelle

5. Parts of a cell

6. Cytoplasm - composition
It is a clear, gel like fluid with in a cell that is external to nuclear and internal to cell membrane
Protoplasm is the Nucleus and cytoplasm
Cytoplasm is composed of :
water(80%); salts, proteins and Nucleic acids
Have cell organelle and cytoskeletal fibers
online.com

7. Cytosole or Cytosolic matrix A part of cytoplasm
Cytosole is a gel like fluid found in the cells A part of Cytoplasm -
It constitutes the intracellular fluid (ICF) and have mixture of substances dissolved in water
Has elevated level of K+ and low N+ ions. Inside is – ive
Ca is also available
Water soluble proteins make up 25-30% of the cytosole

8. Composition of cytosole - significance
K and Na are essential for the generation of action potential in muscles, neurons and endocrine
Both are involved in osmo regulation
Ca is also available for cell signaling and as 2nd messenger
Is seat for metabolic pathways (Glycolysis) and medium for the transport of metabolites and organelle
online.com –

9. Cytosole

10. Cytoskeleton – the structure A net work of filaments
It is the collective name given to protein filaments and motor proteins like Myosin in the cell
These protein filaments form an enormous 3D mesh work
The filaments can be cross linked with other similar filaments through accessory proteins
The cross linkage ↑cell rigidity and maintains its shape
society for cell biology.com

11. Cytoskeleton - structure cont. Nature of fibers
These filaments extend from plasma membrane to nucleus that act both as muscle and skeleton
These are of 3 types:
Microfilaments
Microtubules and
Intermediate filaments
project for cell biology.com – webster.com

12. Types of fibers in cytoskeleton

13. Cytoskeleton – significance movers and shapers
Determining cell shape and allowing the cell to move like: Cilia, flagella and Leukocytes in blood circulation
Provide mechanical strength
Separation of chromosomes in cell division
Provides pathways that directs the movement of organelles and other substances within cells.
Some of the filaments are used to transport cargo- micro tubules
society for cell biology.com

14. Cell organelle – Endoplasmic reticulum (ER)
It is a complex net work of tubules and cisterns in the cell
Well connected with the Golgi complex
Two types depending upon the appearance
Rough Endoplasmic Reticulum, synthesize proteins
Smooth Endoplasmic reticulum for Lipids and CHO synthesis
Transports products to their destinations like Golgi

15. Golgi complex
A collection of tubules/cisterns/sacs that are arranged in stacks
Process, modifies and packs the products from ER
Releases finished products for use inside/outside the cell
Synthesizes complex CHO moles that cannot be synthesized in the SER like Chondroitine sulphate and Hyaluronic acid
Adds CHOs to the lipids and proteins – Glycolipids and Glycoproteins

16. ER and Golgi complex

17. Lysosome and Peroxisome
These are the recycling centre of the cell
Act as waste box for the cell
Lysosome digest the cell debris/organelle, food particles and bacteria and moles by Endocytosis
Peroxisome oxidize the moles like Fatty acids for energy
Detoxication of H2O2 into O2 and water

18. Lysosome

19. Mitochondria
Are power house for the cell, release energy by oxidation of Fatty acids to produce ATP
Have their own genetic material , separate from the DNA in the nucleus,
Synthesize their own proteins
Have double layered membrane

20. Mitochondrion

21. Nucleus
It is the house for the storage of genetic material DNA in chromosomes and nucleoproteins
Controls all activities of the cell especially DNA replication, growth, reproduction and metabolism
Contain nucleolus
Covered by a double layered membrane with pores
Give rise to (Transcribe) mRNA for protein synthesis

22. Nucleus

23. Plasma membrane It is the phospholpid Bilayer with embedded proteins
It is the outer most covering of a cell that isolates the inside of the cell from exterior
Maintains the shape and integrity of the cell
Allows nutrients to pass in and waste to pass out
Protects the cell

24. Plasma membrane

25. Ribosome - structure
Ribosome is the Cytoplasmic organelles that has no membrane
Ribosome decodes the genetic information in mRNA to produce proteins
Two types: free floating and fixed to the RER in the cytoplasm
Both produce proteins for their use :
inside and out side of the cell

26. Ribosome

27. Secretary vesicles
Are the membrane bound rounded structure that are produced and released by the ER and Golgi respectively.
Contain the macro moles in the precursor form as zymogens
Are released in active form as enzyme or hormone
Are stored in the cytoplasm or released out side the cell by the process of Endocytosis
– on line.com