This PPT is for medical students, i.e MBBS, BDS, Nursing, etc

1. The Cell
Structural and Functional
Unit of Life

3. Cell was first discovered by
Robert Hooke in 1665.

4. What is the cell ?

Structural and Functional Unit of Life.

A cell is the basic unit that is
capable of performing life functions.

5. Types of Cells
 Prokaryotic cell lack a nucleus or
membrane-bound structures (e.g.bacteria)
 Eukaryotic cell have a nucleus and
membrane-bound organelles (e.g.animals plants, fungi)

6. Prokaryotic cells
Naked DNA no
nuclei
Few internal
structures
One-celled
organisms,
Bacteria

7. Structure of the Cell
Mitochondria
Plasma membrane
Nucleus
Ribosome
Lysosome
Vesicle
Cytoskeleton
Peroxisome
Rough
Endoplasmic Reticulum
Golgi apparatus

8. Structure of the Cell

9. ISOLATION OF SUBCELLULAR ORGANELLES
Homogenizationwith help of glass/teflon homogenizer cells are
disrupted by- suspending in isotonic soln (0.25 M
buffer at pH 7.4)
Differential velocity Centrifugation.

Separation based on their size.

10. ISOLATION OF SUBCELLULAR ORGANELLES
Supernatant
960 g
10 min
pellet
Homogenate
25000 g
10 min
pellet
Nuclei
DNA
polymerase
Supernatant
34000 g
30 min
pellet
Supernatant
Supernatant
cytosol
105000 g
100 min
LDH
pellet
Mitochondria Golgi complex
Lysosomes,
Galacosyl
Peroxisomes
transferase
ATP synthase,
Acid phosphatase,
catalase
pellet
E. Reticulum
G 6 PD

11. Parts of the Cell

Plasma membrane

Nucleus

Cytoplasm

12. Nucleus

prominent and large
organelle

houses most of a
cell’s DNA.

contains genes

Controls the activity
of other organelles.

13. Structure of Nucleus
a spherical or oval-shaped structure.
Most cells have a single nucleus, although some,
such as mature RBCs, have none. In contrast,
skeletal muscle cells have multiple nuclei.
the nuclear envelope, membrane of the nuclear is
continuous with rough ER
nuclear pores
Each nuclear pore consists of a circular
arrangement of proteins surrounding a large
central opening

14. Functions
1. Controls cellular structure.
2. Directs cellular activities.
3. Produces ribosomes in nucleoli.
Chromatin
Polyribosome
Nucleolus
Nuclear
envelope
Nuclear pore
Nuclear
pore
Rough endoplasmic
reticulum
The nuclear envelope
Details of the nucleus

15.  Ribosomes are the sites of protein
synthesis.
 The name of these tiny organelles
reflects their high content of rRNA.
 They either attached to RER or
float freely in cytoplasm.
 consists of two subunits.
- large subunit
- small subunit.

16. 
A network of membranes in
the form of flattened sacs
or tubules

Two types
-Rough ER
-Smooth ER

17. Nuclear envelope
Ribosomes
Rough ER
Smooth ER

18. 1. Rough ER synthesizes proteins.
2. RER involved in post-translation modifications
such as glycation.
3. SER synthesizes phospholipids, cholesterol (in
many tissue) & steroid hormones (adrenals,
gonads).
4. SER is site of Glycogen metabolism.
5. Stores & releases calcium ions in the cells. (that
trigger contraction in muscle cells.)
6. In liver & Kidney SER Detoxifies drugs & harmful
substances;
7. Removes the phosphate group from G-6-P; and
release free glucose in blood.

19.  It consists of 3 to 20 cisternae, small,
flattened membranous sacs.
 Most cells have several Golgi complexes
 Golgi complexes are more extensive in
cells that secrete proteins
 Modifies, sorts, packages, & transports
proteins received from the rough ER

20. Processing and packaging of proteins by the Golgi complex.

21. Elongated or rod shaped.
“powerhouses” of the cell.
No. may as few as hundred
or as many as several
thousand, depending on the
activity of the cell.
Active cells such as muscles,
liver, and kidneys, which use
ATP at a high rate, have a
large number of Mitochondria

22. Mitochondria
Outer mitochondrial
membrane
Inner mitochondrial
membrane
Matrix
Cristae
Ribosome
Enzymes
Function
Generate ATP through reactions of
ETC.
 Helps in Biochemical reactions. Such
as oxidation of fatty acids, TCA, etc

23. Membrane-enclosed vesicles that
form from the Golgi complex.
60 kinds of powerful digestive
and hydrolytic enzymes.
Lysosomal enzymes also help
recycle worn-out cell structures.
Helps in fertilization.
Some disorders are caused by
faulty or absent lysosomal
enzymes. e.g, Niemann pick
disease, Gaucher’s disease.

24.  Similar in structure to lysosomes, but smaller in size.
 Contain several oxidases, enzymes that can oxidize
various organic substances.
Functions : Degradation of amino acids, oxidation of long chain
fatty acids.
 Oxidize toxic substances, such as alcohol.
 protect other parts of the cell from the toxic effects
of H2O2.
 Dysfunction of Peroxisomes leads to Zellweger syndrome

25. The Cytoskeleton
 A network of protein filaments that
extends throughout the cytoplasm.
Three types of filamentous proteins
contribute to the cytoskeleton’s structure,



Microtubules
Intermediate filaments
Microfilaments

26. The Cytoskeleton
cont…..
Microtubules: Long, Hollow, unbranched, polar cylinders.
 mead up of protein “tubulin”(α & β tubulin)
 The largest of cytoskeletal components.

27. The Cytoskeleton
cont…..
Microtubules: Functions:-
 Microtubules help in structural support,
 To maintain the shape of the cell.
 Movement of organelles such as secretary vesicles,
chromosomes during cell division.
 Forms mitotic spindles during mitosis.
 Movement of cilia and flagella.
 Disorder: Primary ciliary dyskinesia- associated with celiary dysfunction
 clinical effect- recurrent upper & lower resp. tract infection,
male infertility

28. The Cytoskeleton
cont…..
INTERMEDIATE FILAMENTS :



Polymers of long rod like proteins.
these filaments are thicker than microfilaments
but thinner than microtubules.
Functions :Provide mechanical support to the cell.

29. The Cytoskeleton
cont…..
Microfilament




Thinnest elements of the cytoskeleton.
Composed of the protein actin,
Most abundant intracellular protein that that
conc. Just under the plasma membrane.
Most prevalent at the edge of a cell
Functions :

Mechanical support for the basic strength &
shapes of cells.
Microfilaments are involved in muscle
contraction, cell division, and cell locomotion.