Cellular level of organization

Prepared by

Mr. Abhay S. Joshi

Assistant Professor

Yash Institute of Pharmacy,

Aurangabad

abhay.joshirss@gmail.com

CELL

•A cell is the basic, living, structural and functional unit of living organisms.

•There are about 200 different types of cells in our body.

•All cells produced by the process of cell division.

•Cell biology is the study of cellular structure and function.

•Structure of the cell is intimately related to its function.

PARTS OF A CELL

1. Plasma membrane

2. Cytoplasm

a) Cytosol

b) Organelles

3) Nucleus

The plasma membrane

•Structure:

• The membrane is composed of proteins and lipids (phospholipids).

• It bind together by non covalent forces

• The phospholipid molecules have head which is electrically charged and hydrophilic in nature. A tail which has no charge and hydrophobic in nature.

• In this layer the sugar molecule is embedded in between them.

Functions

• Protection

• Barrier

• Shape of the cell

• Cell junction

• Cell movement

• Selective permeability

• Impulse transmission

Cytoplasm

• The cytoplasm has two components

a) Cytosol:

• It is the fluid portion of cytoplasm that contains water (75-90 %), ions, amino acids, proteins, lipids, ATP and waste products.

b) Organelles:

1. Ribosomes

2. Endoplasmic reticulum (smooth & rough)

3. Golgi complex

4. Mitochondria

5. Nucleus

Ribosomes

• These are tiny granules composed of RNA & protein.

• They synthesize protein from amino acids using RNA.

• When this is present in free units in the cytoplasm, the ribosomes make proteins for use within the cell.

• Ribosomes are also found on the outer surface of the nuclear envelope and rough endoplasmic reticulum where they manufacture proteins for export from the cell.

Endoplasmic Reticulum

• It is the series of interconnecting membranous canals in the cytoplasm.

There are 2 types of endoplasmic reticulum

1. Smooth endoplasmic reticulum:

• Here is lack of ribosomes

2. Rough endoplasmic reticulum:

• This is studded with ribosomes that synthesize proteins.

Golgi apparatus

• It consist of stack of closely folded flattened membranous sac.

• It present in all cells but is larger in those cells that synthesize and export proteins.

• The proteins move from ER to golgi apparatus where they are ‘packaged’ into membrane bound vesical called secretory granules.

• The vesicles are stored and when needed more to plasma membrane, through which the proteins are exported.

Nucleus

• Every cell in the body has nucleus, with exception of mature RBC.

• Skeletal muscle and some other cell contain several nuclei.

• It is the larger organelle of the cell and is contained within the nuclear envelope.

• The nucleus contains body’s genetic material which directs all metabolic activities of the cell.

• This consist of 46 chromosomes,

which are made from DNA.

Mitochondria

• This is also called ‘Power House’ of

cell.

• They are involved in the aerobic

respiration. The process by which

chemical energy is made available in

the cell.

• This energy is in the form of ATP

which release energy when the cell

break it down.

• Synthesis of ATP is most efficient in

the final stage of aerobic respiration.

A process requiring oxygen.

THANK YOU