Tip:
Highlight text to annotate it
X
Cell Organization and Sub cellular Structure Studies
Cells are the basic structural and functional units of every organism. All living cells
can be classified into two distinct types – prokaryotic and eukaryotic cell. The words
- eukaryotic means” true nucleus” and prokaryotic means “before nucleus”; were
reflecting the fact that prokaryotic cells are evolved before eukaryotic cells. Organisms
of the domain bacteria and archae consist of prokaryotic cells. Protests, fungi, animals,
and plants all consist of eukaryotic cells. Both prokaryotic and eukaryotic cells share
certain basic features. They are all bounded by a selective barrier called plasma membrane.
Inside all cells is a semi fluid, that is a gelly like substance called cytosol in which
sub -cellular components are suspended. All cells contain chromosomes and ribsomes.
The main differences between prokaryotic and eukaryotic cells are, prokaryotic cells do
not have a pre-defined nucleus and contain no membrane-bound organelles but eukaryotic
cells contain true nuclei and have membrane-bound organelles. Prokaryotic cells have circular
chromosomes and lack histone proteins while eukaryotic cells have linear DNA and contain
histone proteins. The size of the prokaryotic cells is smaller when compared to eukaryotic
cells. Prokaryotic cells have a primitive cytoskeletal structure where in eukaryotic
cells have a complex cytoskeletal structure.
Microscopic view of a prokaryotic cell We require the following materials; laminar
Air Flow Chamber, Bunsen burner, inoculation loop, Slide, Spirit, Saline water, Crystal
violet, Organism or sample, Tissue paper, Light microscope and immersion oil to get
the microscopic view of a prokaryotic cell, We can start the procedure by switching on
the Laminar Air Flow Chamber. To clean the chamber, pour some spirit and wipe this with
some cotton. Arrange all the required materials in the Laminar Air Flow chamber and flame
the Bunsen burner. Clean the slide using the tissue paper and spirit and transfer one drop
of saline water into the slide. Then take a loop and flame it in Bunsen burner till
it becomes red hot and allow it to cool sufficiently. Now open the culture plate and pick one isolated
colony from the sample. Spread it in an oval shape over the saline water on the slide using
the loop. After use, sterilize the loop by heating it over the burner. Now take the slide
and wave it over the flame to fix the organism on the slide. Add 4 or 5 drops of crystal
violet over the slide and keep it for 1 minute to stain the organism. Wash off the excess
stain and wipe it using the tissue paper. Next, switch on the microscope and place the
slide on the stage of the microscope and observe at 10x and 40 x. Then add 1 drop of immersion
oil on the sample and again view the slide at 100x. Through the microscope, we can clearly
see Gram positive cocci cells which are spherical in shape.
Microscopic view of Eukaryotic cells in plants The materials required to view the eukaryotic
cells in plants through the microscope are; Onion, Iodine solution, forceps, slide, scalpel,
distilled water and cover slip. First take an onion and peel off the outer
layer using scalpel. Now using the forceps, carefully peel off the thin red outer layer
of onion and place this section over the slide. Add a drop of distilled water on to the onion
cells and spread the onion peel properly. Add one drop of iodine solution to it and
place the cover slip properly over the section on the slide. Now place the whole slide on
the stage of the microscope and observe at 4x, 10x and 40x. We can clearly view the onion
epidermal cells through the microscope.
Microscopic view of Eukaryotic cells in animals To get the microscopic view of eukaryotic
cells in animals, we require materials like saline water, cover slip, methylene blue stain,
slide, buccal mucosal cells scraper, spirit and tissue paper.
The procedure begins by adding 1 drop of saline water on the centre of the slide. To take
the cheek cell, first sterilize the ‘buccal mucosal cells scraper’ with tissue paper
using sprit. Then take out cheek cells and mix it with saline water on the slide. Add
one drop of methylene blue on the cheek cells and place the cover slip over the cheek cell.
Place the whole slide on the stage of the microscope and observe at 4x, 10x and 40x.
The cheek epithelial cells can be clearly viewed through the microscope.
Precautions: Ensure that while placing the cover slip over
the section; avoid the presence of air bubbles in between the cover slip and section and
wipe off excess stain.