NEET Entrance Exam NCERT Biology

The membrane which is out side the Plasma membrane is called Cellwall. Discovered by - Robert Hook - it has outer wall of cell.  -  rigid membrane.  -  provide Strangth of cell.  -  it is found in Plant cell, Fungi, Prokaryot( except Mycoplasma).  NOTE-Mycoplasma is smallest cell without cellwall.  Chemical nature of cell wall-: 1)  Prokaryotic cell wall - Peptidoglycon .  2)  Fungus cell wall- Chitin (homo polysaccharides which is N-acetyl glucosamine).   3)  Plant cell wall- Cellulose . NOTE-In animal cellwall are absent.  Structure of cell wall-: Cell wall is Madeup of 3 layer-:             Middle lamella ( innermost layer )                # Madeup of Ca & Mg pactet                        ।।।            1)   Primary cellwall       ...

*Plasma membrane is also called Bio-membrane/Cell membrane. Properties of Plasma membrane-:  - Madeup of (Protein+ Phospholipid).    - it is selectively permable membrane.   - it is a Dynamic membrane. Type of Plasma Membrane-: These are mainly three type   1) Sandwich Model  2) Unit Membrane Model  3) Fluid Mosaic Model  1)Sandwich Model-:    - given by " Danielli & Davson"    Ques - Why this is called sandwich model?   Ans a)  Plasma membrane are Madeup of Protein & Phospholipid.         b)  Protein are Madeup of alpha-globular structure.           c) Phospholipid are amphipathic in nature. Amphipathic means--each Phospholipid are two end - 1)Head end which is madeup of glycerol and Hydrophilic(loving with water) in nature.    2)Tail end which is madeup of Fatty acid chain and Hydrophobic(hate with water) in nature.     ...

Cell discovered by - Robert Hooke he observed slide of cork structure. This cork was plant of Quercas .  * Cork is dead structure.  * 1stly Robert Hooke discovered- Dead Cell . * 1stly Antonvan leeuwenhock discovered - Living Cell. *Robert Brown - discovered the Nucleus. * Cell theory was given by - Schleiden & Schwann.  # Size of Cell-: 1- Smallest cell-PPLO/Mycoplasma(these are without cellwall).  Note - 1) Smallest cell with cellwall-Bacteria/Prokaryote.  2) -Largest cell - Ostrich egg cell. #Shape, Size of all type of cell-: a) irregular cell-Amoeba & WBC b) Spindle Shape-Smooth muscle fiber c) Rectangular shape- Skeletal muscle  TYPE OF CELL-: 1) Prokaryotic cell 2) Eukaryotic cell 1) Prokaryotic cell-: # Structure of Prokaryotic cell * 70s type Ribosome * cell wall madeup-Peptidoglycon * membrane bound organelles are absent.  * all enzyme present in cytoplasm.  * DNA are circular.          Eg. Bacteria...