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
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
