1. discoverd ?
   1. Leeuwenhoek
      1. the free living cells in pond water for the first time
   2. by Robert Hooke in 1665
   3. Robert Brown, in 1831
      1. discovered the nucleus in the cell.
   4. Purkinje, in 1839, coined the term ‘protoplasm’
   5. cell theory
      1. ?
         1. that all the plants & animals are composed of cells
         2. cell is the basic unit of life
   6. virchow
   7. presented by 2 biologists
      1. Schleiden (1838)
      2. Schwann (1839)
2. why do the cell need to be small ?
   1. smaller cells have larger surface area
      1. allow more nutrient to come into the cell
      2. more metabolic waste
         1. can be thrown out of the cell
      3. respiratory gases can diffuse
         1. in & out of the cell
      4. any damage to the cell
         1. can be easily
            1. repairable
3. Different shapes & sizes of the animal cell
4. Cell organelles
   1. Plasma / cell membrane
      1. outermost covering of the cell that
         1. separates the contents of the cell from its external environment.
      2. It is a selectively permeable membrane as .
         1. it allows diffusion of
            1. gases like CO2 & O2
            2. water (osmosis)
      3. It enables
         1. endocytosis
            1. due to its flexibility.
            2. Eg. - amoeba.
      4. made up of organic molecules called
         1. lipids
         2. proteins
   2. cell wall
      1. plants, fungi & bacteria
         1. have cell wall
            1. i.e
            2. Cell’s rigid outer covering
            3. outside the plasma membrane.
            4. help them to resist osmosis
            5. Plasmo-lysis
            6. permit the cells of plants, fungi & bacteria
            7. to withstand very dilute (hypotonic) external media
            8. without bursting.
            9. exception - animal
      2. plant cell wall
         1. mainly composed of cellulose.
         2. further divided into
            1. primary cell wall
            2. 2ndary cell wall
            3. middle lamella
   3. Nucleus
      1. largest organell of the cell
      2. spherical structure at the centre of the cell.
      3. has a double layered nuclear membrane/ envelop & pores
      4. brain of the cell
      5. plays an important role in
         1. cell division
         2. development of the cell.
         3. regulates cellular function
      6. Nucleus contains
         1. thread like structure ka
            1. chroma-tine
            2. condensed DNA
            3. chroma-tid
            4. max condensed DNA
         2. nucleous
            1. paeticipation in protein syntheseis
            2. by forming & storing
            3. RNA
         3. rod shaped
            1. chromosomes.
            2. ?
            3. are composed of
            4. DNA
            5. PROTEIN
         4. basic
         5. . . .
      7. which allows the transfer of material from the nucleus.
   4. Cytoplasm
      1. fluid content
         1. inside the plasma membrane.
      2. material inside cell / plasma membrane
         1. excluding the nucleus
   5. others
      1. Endoplasmic Reticulum (ER)
         1. large network of membrane-bound tubes & sheets.
         2. 2 types
            1. rough endoplasmic reticulum (RER) -
            2. smooth endoplasmic reticulum (SER)
         3. Membrane biogenesis
         4. Some other
            1. proteins & lipids
            2. function as enzymes & hormones.
         5. . .
      2. Golgi apparatus
         1. consists of a
            1. system of membrane-bound vesicles
         2. functions include
            1. storage,
            2. modification
            3. packaging of products
         3. also involved in the formation of lysosomes
         4. into membrane bound vesicles.
            1. dispatched to various targets inside & outside the cell through the Golgi apparatus.
      3. Lysosomes
         1. membrane-bound sacs
         2. filled with digestive enzymes
            1. which are made by RER.
         3. aka
            1. suicidal bags
         4. i.e how ?
            1. digests foreign material
            2. worn-out cell organelles
      4. Mitochondria
         1. powerhouse of the cell
            1. as they release the energy
            2. required for various chemical activities needed for life
            3. in the form of ATP (Adenosine triphopshate) molecule
            4. ATP -ka - the energy currency of the cell.
         2. have 2 membrane coverings
            1. outer membrane is porous
            2. inner membrane is deeply folded.
         3. has it's own independent
            1. genome / DNA
      5. Plastids
         1. present only in plant cells
         2. 2 types of plastids
            1. chromoplasts
            2. coloured plastids
            3. containing
            4. the pigment chlorophyll aka chloroplasts
            5. various yellow or orange pigments.
            6. numerous membrane layers
            7. embedded in the stroma
            8. leucoplasts
            9. white or colourless plastids
            10. primarily organelles in which materials such as
            11. starch, oils & protein granules are stored.
         3. Like the mitochondria
            1. plastids also have their own DNA & ribosomes
      6. Vacuoles
         1. storage sacs
            1. for solid or liquid contents
            2. like amino acids, sugars, various organic acids and some proteins.
         2. . .
            1. are small sized in animal cells
            2. plant cells have very large vacuoles.
         3. In plant cells
            1. vacuoles are full of cell sap
            2. provide turgidity and rigidity to the cell.
         4. outer membranne of vacules ka tonoplast
5. types
   1. PRO-KARYOTIC CELL
   2. EU-KARYOTIC CELL
6. cell division & reproduction
   1. Mitosis
   2. Meiosis