Page 22 - MNU microbiology theoritical 2025

General Microbiology & Immunology (PM 401) Second level Semester 4 2024/2025

Chromosome

- Each cell contains a large single circular genome composed of DNA

referred to as the chromosome of a cell.

- It is located in the nuclear area (Nucleoid), and it is not surrounded by

nuclear membrane.

- This chromosome contains the basic genetic information needed by the cell

to survive and produce daughter cells

Plasmids

• extrachromosomal DNA.

• Plasmids are small, circular, and double-stranded DNA molecules.

• They can transfer from one bacterium to another

• They are not essential for viability

• They carry EXTRA GENES that can be used for special situations such as

⮚ Antibiotic resistance

⮚ Production of toxins

⮚ Synthesis of enzymes

.

2- Appendages

Flagella

• Flagella are structures used by cells to move in aqueous environments

(Motility).

• Flagellum consists of a long filament, a hook and basal body (rings)

General Microbiology & Immunology (PM 401) theoretical handbook Page 11