Cells are the basic unit of all living organisms. There are two main types of cells - complex cells with a nucleus and organelles, and simple cells without a nucleus. Complex cells are known as eukaryotes and include animal, plant, and fungi cells. Simple cells are prokaryotes like bacteria. Key cellular components include the cell membrane, nucleus containing DNA, mitochondria which produces energy, and chloroplasts which perform photosynthesis in plant cells. Organelles are either membrane-bound like the nucleus and mitochondria, or non-membrane bound like ribosomes.

1. Cells
● The basic unit of all living organisms
● Its surrounded by a cell surface
membrane
● Contains genetic material(DNA)
● Contains cytoplasm and organelles

2. Cells
There are two types of cells-
❖ Complex cells
➢ Contains a nucleus surrounded by two
membranes
➢ Nucleus contains the DNA inside
➢ Organisms that have a complex cell
structure is known as Eukaryotes
➢ Cells of eg-animals,plants,fungi
❖ Simple cells
➢ No nucleus
➢ DNA is free in the cytoplasm
➢ Organisms that have a simple cell
structure is known as Prokaryotes
➢ Cells of eg-Bacteria

3. Animal cell Plant cell

4. Cell membrane
● Also known as Plasma membrane
● Both Eukaryotic cells and
Prokaryotic cells are surrounded by
cell surface membrane
● Its about 7nm in size
● Its partially permeable
● Controls the exchange of materials
between cell and its environment

5. Nucleus
● The largest cell organelle. Nucleus is
surrounded by a double membrane called
nuclear envelope.Nucleus contains nucleolus
inside it.
● Nucleus contains chromosomes which contains
DNA,thus it controls the activities of a cell.
● Nucleolus- its function is to make ribosomes
using the information in its own DNA.
● Nuclear envelope-contains many small pores
called nuclear pores,which controls exchange of
materials between the nucleus and cytoplasm.

6. Mitochondria
Structure-
● Surrounded by two membranes.
● Inner membrane folded into cristae
● Cristae projects into the matrix
● Has its own circular DNA and 70S ribosomes
Function-
● Carry out aerobic respiration
○ To release energy
○ Energy is transferred to ATP (the energy
carrying molecule in all living cells)
● Synthesis of lipids
● Reactions of respiration takes place in the matrix and
cristae of the mitochondria.
❖ Thus mitochondria is also known as the Power
House of the cell,as it produces ATP.

7. Golgi apparatus
Structure- stack of flattened sacs called
cisternae,constantly forming at one end and
breaking up into vesicles at the other end.
Function-
● Collects and processes molecules particularly
proteins from RER.
● Sugars are added to proteins and lipids to
make molecules known as Glycoproteins and
Glycolipids.
● After processing molecules are transported in
Golgi vesicles to other parts of the cell or out
of it.
● Golgi vesicles are used to make Lysosomes.

8. Lysosomes
Structure- spherical organelle,surrounded by a single
membrane.Contains digestive enzymes.Present in eukaryotes.
Function-
● It contains enzymes called hydrlases
● Lysosomes engulf and destroy unwanted cell components.
● May fuse with the Endocytic vacuoles formed and digest it.
● Release enzymes from cell for extracellular digestion
(Exocytotis)
● Contents of lysosomes are sometimes released into the
cytoplasm to digest the whole cell.

9. Endoplasmic reticulum(ER)
and Ribosomes
● ER are A network of flattened sacs running through cytoplasm.
● Its Present in Eukaryotes.
➔ Two types of ER: 1.Rough ER 2.Smooth ER
◆ RoughER: Covered with Ribosomes.
Continuous with the nucleus.
Synthesises and Packages secretory
proteins.
◆ SmoothER: Lacks ribosomes
Makes lipids,cholesterol,reproductive hormones.
Storage site for Calcium ions.
Ribosomes:
● Are found in all cells
● Involved in protein synthesis
● Eukaryotic ribosomes are 80S and Prokaryotic ribosomes are
70S.
● Mitochondria and chloroplasts contain their own 70S
ribosomes.

10. Cell wall
● Present in plant cells and prokaryotes
● Plant cell walls are made up of Cellulose running parallel
in different directions.
● Its fully permeable.
Functions-
● Provides mechanical strength and support
● Prevents cells from bursting by osmosis
● Arrangement of the cellulose fibres determines the shape
of cell
● Control of water and minerals uptaken by the plant
● Reduces waterloss due to the presence of waxy cuticle on
their outerwalls in epidermal cells

11. Vacuoles and Chloroplasts
Vacuoles: Plant cell have a Large central vacuole. Has a
single membrane called tonoplast. Vacuole functions are:-
● Support the cell due to its turgidity
● Lysosomal activity
● Food reservers,such as sucrose or mineral salts.
● May Store waste products.
● Growth in size
Chloroplasts: Present in plant cells
● Surrounded by double membranes.
● Chloroplast carries out photosynthesis.
● Contains pigment known as chlorophyll which absorbs
light energy.
● Produces ATP
● Has its own circular DNA and 70S ribosomes

12. Double membrane bound organelle: Nucleus,
mitochondria, chloroplast
• Single membrane bound organelle:
Lysosome, Golgi Body, Endoplasmic reticulum,
Vacuole
• Organelle without membrane: Cell wall,
Ribosome, Cytoskeleton.
• Only found in animal cell : Centriole
• Only Found in Plant cell: Cell wall, Large
central vacuole, Chloroplast
• Has own Circular DNA and 70s ribosome,
synthesise ATP : mitochondria, chloroplast.
• Flattened sac in ER and golgi body =
Cisternae
• Inner folding in mitochondria = Cristae

14. Virus

16. peroxisome
centrosome
microtubule

17. Peroxisome