Cellular Structure:
* Prokaryotic: Lack a true nucleus and other membrane-bound organelles. Their DNA is located in a region called the nucleoid, which is not enclosed by a membrane.
* Unicellular: They are single-celled organisms.
* Cell Wall: Most bacteria have a rigid cell wall made of peptidoglycan, which provides structural support.
* Plasma membrane: Surrounds the cytoplasm and regulates what enters and exits the cell.
* Ribosomes: Smaller than eukaryotic ribosomes (70S), involved in protein synthesis.
Metabolism:
* Diverse metabolic capabilities: Bacteria exhibit a wide range of metabolic pathways, allowing them to thrive in diverse environments and use various energy sources.
* Autotrophs and heterotrophs: Some bacteria can make their own food (autotrophs) through photosynthesis or chemosynthesis, while others obtain energy by consuming organic compounds (heterotrophs).
Reproduction:
* Asexual reproduction: Bacteria primarily reproduce asexually through binary fission, where a single cell divides into two identical daughter cells.
* Genetic transfer: Some bacteria can exchange genetic material through horizontal gene transfer, which contributes to their rapid evolution and adaptation.
Other Features:
* Microscopic size: Bacteria are generally microscopic, ranging from 0.5 to 10 micrometers in diameter.
* Wide range of shapes: Bacteria come in various shapes, including spheres (cocci), rods (bacilli), spirals (spirilla), and comma-shaped (vibrios).
* Importance in ecosystems: Bacteria play crucial roles in nutrient cycling, decomposition, and symbiotic relationships.
* Human health: While some bacteria are beneficial, others can cause diseases in humans and animals.
Key Differences from Archaea:
* Cell wall composition: Bacteria have peptidoglycan in their cell walls, while archaea do not.
* Membrane lipids: Archaea have unique membrane lipids that are more resistant to extreme conditions.
* Gene expression: Archaea have some gene expression mechanisms that are more similar to eukaryotes.
Remember: Bacteria are a diverse group of organisms, and there are many exceptions to these general characteristics.
