Cell, smallest unit of living organism

2. • Smallest structural and Functional unit of an living
organism or micro organism.
• So, it is a basic building block to make a body.
• It is generally microscopic and consist of Cytoplasm and
Nucleus in it.
• Taking the both Cytoplasm and Nucleus together, it is
known as Protoplasm.
• Egg is a cell itself.

3. Discovery of Cell:-
• Discovered by British scientist Robert Hook at 1665. He examined a
thin slice of cork under a microscope and observed honeycomb like
structure. But, unfortunately, the cell was dead.
• After, Antoine van Lewenhoek made his own microscope which was
more powerful than the old simple microscope and observed living
cells in it.

4. Different types of Cell Organelles:-
Cell is consisted of different types of cell organelles. They are-
• Endoplasmic Reticulum
• Golgi Bodies
• Mitochondria
• Ribosome
• Lysosome
• Centrosome
• Plastid
• Nucleus
( Though all are not present in same cell)

5. Description:-
Endoplasmic Reticulum:-
• Continuous membrane system that forms a series of
flattened sacs within the cytoplasm of eukaryotic cells.
• Differences in certain physical and functional
characteristics distinguish the two types of ER, known as
rough ER and smooth ER.
• Rough ER is named for its rough appearance, which is due
to the ribosomes attached to its outer surface.It helps in
the synthesis of Protein.
• Rough ER lies immediately adjacent to the cell nucleus and
its membrane is continuous with the outer membrane of
the nuclear envelope.

6. Golgi Bodies:-
• Golgi apparatus is made up of a series of
compartments and is a collection of fused, flattened
membrane-enclosed disks known as Cisternae.
• A mammalian cell typically contains 40 to 100 stacks
of cisternae.
• The vesicles that leave the rough endoplasmic
reticulum are transported to the cis face of the Golgi
apparatus, where they fuse with the Golgi membrane
and empty their contents into the lumen.
• Golgi Bodies are Made directly from the Endoplasmic
Reticulum And indirectly from the Nucleus.

7. Mitochondria:-
• Mitochondria have a double membrane structure
• Use aerobic respiration to generate ATP, which is used
throughout the cell as a source of chemical energy
• Cristae is made by folding the inner membrane inside. It
looks like finger. Here, Crystalline protein is present.
• Here F1 particles are also known as oxysomes . These
particles are present in matrix side of mitochondrial inner
membrane.
• Matrix consist of Plasma ( water molecules, solid
particles) and circular DNA, RNA, Ribosome, Protein
and Enzymes

8. Ribosome:-
• The ribosome is a complex cellular machine. It is
largely made up of specialized RNA known as ribosomal
RNA (rRNA)
• The ribosomal proteins and rRNAs are arranged into
two distinct ribosomal pieces of different sizes, known
generally as the large and small subunit of the
ribosome.
• Prokaryotic cell has 70S ribosome made up from a 50S
large subunit, a 30S small subunit
• Eukaryotic cell has 80S ribosome made up from a 60S
large subunit, a 40S small subunit
• It helps in the Protein synthesis.

9. Lysosome:-
• Lysosomes are membrane enclosed organelles that
contains a numbers of enzymes capable for breaking
down some polymers
• Lysosome is also known as ‘Suicidal Bag’
• Lysosomes are originated by budding off from the
membrane of the trans-Golgi network
• Primary Lysosome, Secondary Lysosome,
Autophagosome, Residual bodies are the states of
lysosome.
• Inside lysosomes there are some
enzymes(Hydrolytic) like-Nucleases, Phosphatases,
Sulphatases, Lipases, Proteases, Glycosidases

10. Centrosome:-
• organelle that serves as the main microtubule
organizing center of the animal cell.
• It is absent in the Plant cells.
• The centrosome provides structure for the cell.
• Centrosomes are composed of
two centrioles arranged at right angles to each
other, and surrounded by a dense, highly structured
mass of protein
• The function of centrosomes in this context is
hypothesized to ensure the fidelity of cell division

11. Plastid:-
• Plastids that contain chlorophyll can carry
out photosynthesis and are called chloroplasts.
• Plastids can also store products like starch and can
synthesize fatty acids and terpenes, which can be used for
producing energy and as raw material for the synthesis of
other molecules.
• There are so many types of Plastids which helps in several
processes they are-
•Chloroplasts: typically green plastids used for photosynthesis.
•Chromoplasts: coloured plastids for pigment synthesis and
storage
•Leucoplasts: colourless plastids for monoterpene synthesis;
leucoplasts sometimes differentiate into more specialized
plastids:
• Amyloplasts: for starch storage
• Elaioplasts: for storing fat
• Proteinoplasts: for storing and modifying protein

12. Nucleus:-
• Most Important Part of a cell. It is also known as the Brain
of cell
• It is made by 4 basic parts. That are-
Nuclear Envelope
Nuclear Lamina
Nucleoplasm
Nucleolus
• Nuclear Envelope Gives the structure to the nucleus.
• From Nuclear Lamina, Chromatid are made and
Chromosome from that
• In the Nucleoplasm, DNA Replication, RNA Transcription
take place.
• The size of the nucleus is correlated to the size of the
cell, and this ratio is reported across a range of cell types
and species.In eukaryotes the nucleus in many cells
typically occupies 10% of the cell volume.