Cell & Organelles

Division of Parts of Cell
1. Cell Membrane/Plasma Membrane
2. Protoplasm
1. Nuclear Membrane
2. Nucleolus
3. Nucleoplasm
4. Chromatin
1. Organelles (Living)
2. Inclusion (Non-living, Temporary)
Cell Membrane
The cell membrane is the bilayer (two layers) of phospholipid molecules composed of the hydrophilic part and hydrophobic part.
Outer parts of both phospholipid layer is a hydrophilic part (i.e soluble in water).
Inner part of both phospholipid layers form the middle part - hydrophobic part (i.e not soluble in water).
Two outer surfaces→ hydrophilic
Inner central part → hydrophobic
Within this bilayer of phospholipid, proteins are embedded.
Protein present through the vertical length of membrane → called as integral protein (transmembrane protein)
Protein present in the inner aspect of the membrane near the transmembrane protein called → peripheral protein.
Similarly, it consists of carbohydrate molecules as glycoprotein and glycolipid commonly called as glycocalyx.

Function of lipid bilayer
It is permeable to fat-soluble substances (such as 02, Co2) but impermeable to water-soluble substances like ions, glucose, urea & other.
 Thus, for these ions, glucose, for their transport inside the cell, proteins are present as water channels, Na-K pump, transporter.
Function of cell membrane
• It forms the boundary of the cell.
• Maintains the shape of the cell.
• Acts as a selective barrier that regulates the passage of certain materials into or out of the cell.
• Serves as the site of the receptor (protein act as receptor).
• Limits the protoplasmic content of the cell.
Organelles are the living highly organized physical structures.
Two types of organelles: -
1) Membrane bounded
2) Non-membranous
Membranous organelles
1) Mitochondria
2) Peroxisomes
3) Lysosomes
4) Endoplasmic reticulum
5) Golgi complex.
Non-membranous organelles
1) Ribosome
2) Centrosome
3) Microfilament and Microtubules
4) Centriole
They are the structures present in the cytoplasm which are non-living, temporary constituents of the cell membrane.
1) Stored foods (i.e CHO, Proteins & Fats)
2) Secretory granules
3) Pigment granules
Cytoskeleton of cell:
Complex network of microtubules, microfilaments, and Intermediate filaments.
Functions: -
1) Provides shape of the cells
2) Gives support to the cell
3) Participates in the movement of organelles, vesicles.
Difference between organelles & inclusions
Organelles: Inclusions:
• Permanent components of cell • Temporary components
• Highly organized physical Structure • They are raw food materials or product of metabolism
• Eg. Mitochondria, ER, Golgi bodies • Eg: Secretory granules, pigment, CHO, Protein

Difference between RNA & DNA
• Double-stranded • Single-stranded
• Found in nucleus (99%), mitochondria (1%) • Found in the cytoplasm (90%), nucleus (10%.)
• nitrogen bases are Adenine, Guanine, cytosine, Thymine • Nitrogen bases are Adenine, Guanine, cytosine, Uracil
• Contain deoxyribose sugar • Contain ribose sugar
• Sum of purine bases is equal to the sum of pyrimidine bases. • Sum of the purine base is not equal to the sum of pyrimidine bases.
• Function
Carry genetic information.
• Function:
Translate genetic information of DNA into protein
• Histone protein present. • Histone protein absent.
• Polymer of deoxy-ribonucleotides • Polymer of ribonucleotides