Mikrobiologi - Prokaryoters opbygning | Biotech Academy

Overview of Organisms: Eukaryotes vs. Prokaryotes

Classification of Organisms

• All organisms can be categorized as eukaryotes or prokaryotes, based on the structure of individual cells.

• The main difference between these cell types is that eukaryotes have a nucleus, while prokaryotes do not.

• Prokaryotes include bacteria and archaea, with bacteria being the most prevalent group.

Structure of Bacterial Cells

Cell Membrane and DNA Location

• A bacterial cell is surrounded by a plasma membrane that separates its internal environment from the external one.

• This membrane regulates material exchange between the inside and outside, giving the cell control over its contents.

• Unlike eukaryotic cells, bacterial DNA is located freely within the cell.

Components Within Bacterial Cells

Nucleoid and Cytoplasm

• The area where bacterial DNA resides is called the nucleoid; it controls growth, maintenance, and reproduction of the cell.

• The cytoplasm contains ions, small molecules, and proteins like ribosomes which are essential for protein synthesis.

Structural Features of Bacteria

Cell Wall and Membranes

• Some bacteria possess a cell wall with a stable structure that helps maintain their shape.

• Certain bacteria also have an additional outer membrane beyond their cell wall.

Protective Structures in Bacteria

Capsules and Movement

• Surrounding some outer membranes is a slimy layer known as a capsule that protects against attacks from other cells.

• Capsules help prevent dehydration and assist in maintaining contact between cells.

Mobility Mechanisms in Bacteria

Flagella and Pili

• Some bacteria can move using structures called flagella made of protein powered by energy-consuming motors within the cell.

• Another structure called pili aids in connecting to other cells and transferring genetic material.

Summary of Bacterial Adaptations

Survival Strategies

• Bacteria are relatively simple cells but have developed various adaptations such as protective layers, mobility features, and communication methods to enhance survival.