E-Portfolio: Microbiology - Week 7

What is up, people!

This week, we learned on internal structure and its function of a prokaryote with Dr. Wan

Courtesy: https://www.shmoop.com/biology-cells/prokaryotic-cells.html


I am actually quiet interested with plasmid, a small structure, circular, double-stranded DNA molecule that is distinct from a cell's chromosomal DNA. Plasmids naturally exist in bacterial cells, and they also occur in some eukaryotes. Often, the genes carried in plasmids provide bacteria with genetic advantages, such as antibiotic resistance. Plasmids have a wide range of lengths, from roughly one thousand DNA base pairs to hundreds of thousands of base pairs. When a bacterium divides, all of the plasmids contained within the cell are copied such that each daughter cell receives a copy of each plasmid. Bacteria can also transfer plasmids to one another through a process called conjugation using sex pili.

For our experiment this week, we had done Gram staining and Acid-fast staining.

The Gram stain is the most important staining procedure in microbiology. It is used to differentiate between gram positive organisms and gram negative organisms. Hence, it is a differential stain. Gram staining involves a four-part process, which includes crystal violet (the primary stain), iodine (the mordant), a decolorizer made of acetone and alcohol and safranin (the counterstain).

The acid-fast stain is a differential stain used to identify acid-fast organisms such as members of the genus Mycobacterium .Acid-fast organisms are characterized by wax-like, nearly impermeable cell walls; they contain mycolic acid and large amounts of fatty acids, waxes, and complex lipids.  Acid-fast organisms are highly resistant to disinfectants and dry conditions.

These are few pictures of stained microbes under oil immersion.

Mycobacterium smegmatis and Staphylococcus aureus stained with Acid-fast staining under microscope.

Bacillus cereus with endospores stained with Gram staining method under microscope 







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