the anatomy of a cell

1. CELL

2. • Basic structural and functional component of
life
• The body is composed of up to 100 trillion
cells
• Cells are composed of Atoms
• Atoms are bound together to form Molecules
• Molecules are grouped to form Organelles,
which are the functional structures of the Cell

3. TYPES OF CELLS
• 2 types:
– Prokaryotic
• Seen in bacteria only
– Eukaryotic
• Other organisms, including man

5. COMPONENT PARTS OF THE CELL
• Cell membrane
• Cytoplasm and Organelles
• Nucleus
Cytoplasmic components are usually not
distinguishable

6. CELL MEMBRANE
• is a limiting membrane
• separates the interior of the cell from the
extracellular environment
• composed primarily of double-layered
phospholipids
• with proteins are embedded
• visible only with the aid of an electron
microscope
• about 7.5-10 nm diameter

7. FUNCTIONS
• Protects cellular components
• Regulates passage of substances into and out
of the cell.

8. • The permeability of the cell membrane
depends on:
– structure of the cell membrane: thickness,
phospholipids, structural arrangement, etc
– size of molecules
– ionic charge
– lipid solubility
– presence of carrier molecules
– pressure differences

9. MEMBRANE SPECIALISATION

10. • In order to explain the structure and function
of the cell membrane, hypotheses have been
proposed
• first important one was proposed by Danielli
and Daveson in 1955
• Singer and Nicholson postulated the Fluid-
Mosaic Model of cell membrane (1972)

11. FLUID-MOSAIC MODEL
Component:
• proteins are either embedded or floating in
the bilayer.
• the phospholipids of the cell membrane are
arranged in a bilayer to form a fluid-liquid
crystalline matrix or core.
• the proteins are globular and cholesterol
appears sparsely on the external surface of
the membrane

13. • There are 2 forms of proteins based on their
location:
• Extrinsic or peripheral proteins
• Intrinsic or integral proteins
• The extrinsic ones are superficially placed in
the lipid bilayer, while the intrinsic proteins
are deeply embedded in the lipids spanning its
entire length

14. The cell membrane is composed almost entirely
of lipids and proteins. However, CHO are also
present, in form of oligo, or poly-saccharides,
attached either to proteins (glycoproteins) or
lipids (glycolipids), projecting outwards from the
cell surface
• The membrane entirely envelopes the cell. Its
external surface (plasmalemma) is covered with
glycoproteins (cell coat, or glycocalyx)

15. • The World is looking for people that have
solutions to Life’s problems
• Nobel Prizes are usually not won by the bed
side, but on the bench
• Laureates are really not geniuses, but people
who determine to be
– They pay more attention to minute details
• “Find a need and fill it”