Very good and informative

1. Fundamental Unit of Life

2. Cell
 Cell is the fundamental unit of life
 All the living organisms are made up of cell
 It is the structural and functional unit of life because
whole body is made up of cells
 It is known as the fundamental unit of life because it
regulates all the functions inside an organisms
 The cell is a Latin word for “a little room”.
 Robert Hook (1665) discovered Cell.

3. The cell was first discovered and named by Robert Hooke in 1665. He
remarked that it looked strangely similar to cellula or small rooms
which monks inhabited, thus deriving the name. However what Hooke
actually saw was the dead cell walls of plant cells (cork) as it
appeared under the microscope.

4. Postulates of Cell Theory
 In 1838, Matthias Schleiden and Theodor
Schwann proposed a basic cell theory. In 1858, another
scientist, Virchow made an addition to the existing cell
theory.
 the postulates of the modern cell theory are as
follows: Cell is the basic functional & structural unit of
life(all living organisms). All living organisms are
composed of cells & the products of cells. All cells arise
from the division of pre-existing cells.

5. Unicellular and Multicellular Organisms
Unicellular organisms:
 composed of single cell
 Single cell constitute the structure and entire function of
the organisms
 e.g. Amoeba, Paramoecium, Euglena

6. Multicellular organism:
 composed of many cells
 division of labour can be seen in these organisms
 e.g. plants , animals, human beings

7. Cell Structure
 Cells are made up of components called cell organelles
 A cell is capable to live and perform all their respective functions
due to the presence of cell organelles
 The structure seen in almost every cell is same: Plasma
membrane, nucleus and cytoplasm.

8. Cell Wall
 found in plant cells outside the plasma membrane
 rigid covering made up of cellulose
 provide structural support to the plants

9. Plasma membrane and its function
 It is the outermost covering of the cell.
 It is called as selective permeable membrane (because it
prevents movement of some materials).
 It helps in diffusion and osmosis
 Composed of bilayer of lipid and protein

10. Osmosis and Diffusion in cells

11. Nucleus
 small, round and membrane bound structure near center of a cell
 Fluid inside the nucleus in called nucleoplasm
 Covered by double layer called nuclear membrane
 plays a central role in cellular activities/reproduction.
 nucleus contains thread like structure called chromatin material which gets condensed into
chromosomes. The chromosomes contain information for inheritance of features from
parents to next generations in the form of DNA( Deoxyribo Nucleic Acid ) and protein
molecules.
 the functional segments of DNA are called genes

12.  Though part of the function of the nucleus is to
separate the DNA from the rest of the cell,
molecules must still be able to move in and out
(e.g., RNA). Proteins channels known as nuclear
pores form holes in the nuclear envelope. The
nucleus itself is filled with liquid (called
nucleoplasm) and is similar in structure and
function to cytoplasm. It is here within the
nucleoplasm where chromosomes (tightly
packed strands of DNA containing all our
blueprints) are found.

15. Cytoplasm
 thick solution composed of water, salts and proteins that fills
the cell
 surrounded by cell membrane,
 Nucleus of the cell is surrounded by the cytoplasm

16. Cell Organelles
 An organelle is a membrane bound structure found
within a cell. Just like cells have membranes to hold
everything in, these mini-organs are also bound in a
double layer of phospholipids to insulate their little
compartments within the larger cells.
 These organelles are found in the cytoplasm, a viscous
liquid found within the cell membrane that houses the
organelles and is the location of most of the action
happening in a cell.

17. Endoplasmic reticulum is a network of membrane bound tubules, and has close connections to the
nucleus. It is responsible for active and passive transport in the cells, and they are of two types:
Rough Endoplasmic Reticulum: These ER bear ribosomes on their surface and give them a 'rough'
when seen under the microscope. RER is responsible for protein synthesis.
Smooth Endoplasmic reticulum: These ER do not have ribosomes on their surface, and look 'smooth'
under the microscope. SER are responsible for lipid synthesis.

18. Golgi Apparatus
 First described by a scientist Camillo Golgi
 It is a system of membrane bound vesicles
called cisterns
 It functions include the storage,
modification and package of cell products
 The complex sugars are made from simple
sugars in the Golgi apparatus
 It is also involved in the formation of
lysosomes.

19. Lysosomes
 Sac like structure in a cell
surrounded by membrane
 contain powerful digestive
enzymes(enzymes are made by
RER) to digest the worn-out cell
organelles, bacteria etc.
 When the cell gets damaged,
lysosomes may burst and the
enzymes digest their own cell,
hence called as “Suicidal bags of
a cell”. It is a waste disposal
system of the cell.

20. Mitochondria
 It is covered by a double membrane
 Outer membrane is very porous and the
inner membrane is deeply folded
creating a large surface area for ATP
(Adenosine Triphosphate) molecule
synthesis.
 ATP is the energy currency of a cell;
hence the Mitochondria are called as
Power House of a Cell
 Mitochondria have their own DNA and
Ribosomes; therefore they can make
their own proteins

21. Plastids
 Double membrane bound structure
 present only in plant cells
 Have their own DNA and ribosomes
 Enfolding of membrane is called thylakoids
and matrix is called stroma, seat for
enzymatic actions
Two types:
1. Chromoplasts- Colored Plastids: chloroplasts –
contain green pigment (chlorophyll) and useful in
photosynthesis; also contains various other
pigments like yellow or orange
2. Leucoplasts (White or colorless plastids;
stores materials such as oils, proteins, fats etc.

23. Vacuoles are fluid filled organelles surrounded by a
membrane.
Animal cells have small sized vacuoles whereas
plant cells have large vacuoles.
It provides turbidity and rigidity to the plant cell.
It acts as storage sacs of cell and stores food, water,
sugar, minerals and waste products of the cell.