Page 16 - MNU microbiology theoritical 2025

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

Prokaryotes and Eukaryotes

• Microscopically, the members of the Bacteria and Archaea look identical.

• Both are prokaryotes, meaning they are single-celled organisms consisting of a

prokaryotic cell (meaning “prenucleus”).

• This type of cell does not contain a membrane-bound nucleus nor any other

intracellular lipid-bound organelles.

• Their genetic information is stored in deoxyribonucleic acid (DNA) in a region

called the nucleoid.

• Members of the Eucarya are eukaryotes, meaning they are composed of one or

more eukaryotic cells (meaning “true nucleus”).

• These cells always contain a membrane-bound nucleus and other organelles,

making them far more complex than the simple prokaryotes.

• All algae, fungi, protozoa, and multicellular parasites are eukaryotes.

Types of Microorganisms

1. Friendly microorganisms
• Bacteria in our body: Normal flora are microorganisms found in our

intestines that assist in the digestion of food and
play a critical role in the formation of vitamins

• used in the production of food and other
commercial products

2. Harmful microorganisms

• Disease-causing microorganisms known as

pathogenic microorganisms

General Microbiology & Immunology (PM 401) theoretical handbook Page 5