THE CELL : BIOLOGICAL SCIENCES GSA:

Background:

• Living thing (Plants,Animals and Microbes).
• Derived from cellula (small room).
• Microscopic Structure.

==> It was discovered by Robert Hooke in 1665.

==> Later on it was discovered by Robert Brown in 1831 along with the nucleus.

• Cytology (cell biology)
• Schleiden and schwann theory

Living organisms are made up of cell.

Cell is surrounded by a membrane.

Present of nucleus with in cell.

Cell is the basic unit of life.

Cell is the basic structural and functional unit of life.

Cell form ==> Tissue ==> Organs ==> Organ system ==> Living organisms

There are two types of cells.

a) Unicellular     b) multicellular

Every cell perform it's own function.

Generalized Structure and function of cell:

CEll organelles:

a) Cell wall

b) cell membrane/ Plasma membrane.

1. Cell Wall:

• It provides protection to the cell.
• It provides mechanical support to the cell.
• It has a definite shape.
• It provide passage for the exchange of material.
• It has porous pores (pits) which helps in exchange of material.

a) Primary Cell Wall:

• It is the inner most cell wall.
• It is delicate/softer in nature.
• It is flexible and plastically stretchable.
• It is extremely thin.
• It is made up of cellulose.
• It develops in a newly growing cell.

b) Secondary cell wall:

• It is the outer most wall.
• It is thick and stronger.
• It is made up of cellulose and Hemi-cellular Lignin.
• It develops when the cell has attain it's maximum size.
• Once it develops it does not allow any further expansion or enlargement of cell.

c) Middle Lamella:

• It consists of sticky gel like material.
• It consists of water , calcium, potassium, magnesium and waxes.
• It is responsible to hold the cell wall.

2. Cell membrane:

• Cell membrane is present after cell wall.
• It is responsible to provide protection.
• It provides mechanical support.
• It has a definite shape.
• It provides passage for exchange of material.

      ==>Selectively permeable (allows only necessary for cell)

• It is made up of Proteins, lipids and fats.
• Carbohydrates are present in Conjugated form i.e minute concentration.

Fluid Mosaic Model:

• According to Fluid Mosaic Model the plasma membrane is Lipid bi-layer.
• Irregular Protein molecules are scattered across the cell membrane.
• Protein molecules are embedded.
• Protein molecules are present like ice berg.

3.Cytoplasm:

It is a fluid filled region which is present in between the plasma membrane and nuclear membrane is termed as Cytoplasm

• It is a store house of multiple nutrients (vitamins, Sugar, Acid).
• It is that region where the maximum cellular activities takes place.
• Cytoplasm provides a site and protection to other sub-cellular organelles.
• It is also responsible to provide a medium to pass the genetic material.
• It is that region from where the cell expands.
• Cyclosis is a movement of fluid into the cytoplasm.

4. Endo-plasmic Reticulum:

It is a network of cisternae (elongated sacs extending out from the nuclear membrane).

• There are two types.

a) Rough endo-plasmic reticulum:

• Rough appearance.
• Ribosomes are attached with rough endo-plasmic reticulum.

b) Smooth endo-plasmic reticulum:

• It has smooth appearance.
• Ribosomes are not attached with Smooth endo-plasmic reticulum.
• It is involved in synthesis of fats (steroids).

5. Ribosomes:

• There are non-membranous.
• Roughly, Spherical shaped granules. (formed in nucleus)
• They are made up of equal amounts of RNA and Proteins.
• Ribosomes are involved in protein synthesis.

5. Golgi apparatus:

Camillo golgi discover it. 

• It is a network of vesicles.
• Synthesized proteins at the Rough Endo plasmic Reticulum transfers to golgi-complex and golgi-complex is responsible to convert those protein into the further finishing products.

6. Lysosomes /spliting bodies:

• They are released by golgi- complex.
• They are involved in the removal of death cell from the body.

7. Mitochondria:

• It is a double membrane of cell organelles.
• Selfly replicate.
• Number of mitochondria may vary from cell to cell.
• Process of cellular respiration takes place as a result of which the synthesis of ATP( Adenocine tri phosphate). It is the energy currency of cell.

8. Centriole:

• It is only present in animals.
• It is involved in the process of cell division.

9. Vacule:

• Present in both Plant and Animal cells.
• In case of Plant cell large in size present in the center of the cell.
• In case of Animal cell smaller in size and present away from the nucleus.
• Store house of water.

10.Plastids:

It is present only in Plants.

It has three types.

       Chloroplast : 

• It is present in leave cells.
• It is present in the process of photosynthesis.
  Chromoplast:
  
• It is present in petals.
• It is responsible for colour production other than green.
  Leucoplast:
• It is responsible for food storage.

11. Nucleus:

• With the formation of genetic material takes place in nucleus.
• It also involved in the regulation of cellular activities.
• It contains the genetic information.