Bacteria: Pathogens and Structure

Bacteria: Pathogens and Disease

• Bacteria are single-celled prokaryotes
• Some bacteria are pathogenic in plants and animals
• Bacteria cause disease by being a pathogen
• Bacteria reproduce by binary fission.
• DNA replicates and the cell divides into two identical cells

Bacterial Structure

• Capsule: Outermost layer in some bacteria, protects from desiccation, phagocytosis, and antibiotics; helps bacteria adhere to surfaces.
• Cell Wall: Provides structural support, shape, and protection
• Plasma Membrane: Controls the movement of substances in and out of the cell.
• Nucleoid (DNA): Stores and transmits genetic information
• Cytoplasm: Site of many cellular processes, including metabolism
• Pilus (pili): Hair-like structures used for adherence to surfaces , conjugation (exchange of genetic material).
• Ribosomes: Protein-synthesizing structures
• Flagellum (flagella): Whip-like structures for motility (movement).
• Peptidoglycan: A complex mesh-like polymer. Prevents the cell from bursting due to internal pressure.

Types of Bacteria (by Shape)

• Bacillus (bacilli): Rod-shaped Example: Escherichia coli (E. coli), Bacillus subtilis
• Coccus (cocci): Spherical or round-shaped. Example: Streptococcus, Staphylococcus
• Spirillum (spirilla): Spiral or helical-shaped. Example: Helicobacter pylori, Treponema pallidum
• Vibrio: Comma-shaped. Example: Vibrio cholerae

Types of Bacteria (by Gram Stain)

• Gram-positive: Stain purple due to a thick peptidoglycan layer in their cell wall. Example: Staphylococcus aureus, Streptococcus pneumoniae.
• Gram-negative: Stain pink or red due to a thinner peptidoglycan layer and an outer membrane. Example: E. coli, Salmonella

Types of Bacteria (by Oxygen Requirements)

• Aerobic: Require oxygen for growth.
• Anaerobic: Do not require oxygen for growth; may even be harmed by it.
• Facultative anaerobic: Can grow with or without oxygen.

Pathogens

• A pathogen is a microorganism that causes disease.

Bacterial Infections

• Salmonella: A pathogenic bacteria causes food poisoning, caused by poor kitchen hygiene and results in stomach cramps, sickness and diarrhoea.
• Gonorrhea: A bacterial disease transmitted by sexual intercourse. Symptoms include pain urinating, discharge from the penis or vagina, long term can impact fertility. Treated by antibiotics.

Treating Bacterial Infections

• Bacterial diseases can be treated with antibiotics.
• However, bacteria are evolving, becoming resistant to existing antibiotics.
• Therefore, there is a lot of research into finding new antibiotics to fight diseases.

"Good" Bacteria

• Not all bacteria are pathogenic.
• Some are very useful, such as bacteria in the intestines.
• These bacteria help digest food, absorb nutrients, and produce vitamins.

Bacteria vs. Viruses

• Bacteria are larger than viruses.
• Bacteria can be treated with antibiotics.
• Antibiotics are not effective against viruses.
• Bacteria are living organisms, whilst viruses are non-living.
• Viruses only replicate inside a host cell, whereas bacteria can survive and divide on their own.

Explore the fascinating world of bacteria, focusing on their role as pathogens and their unique cellular structures. This quiz covers key concepts including reproduction, bacterial anatomy, and how bacteria cause diseases. Test your knowledge and gain a deeper understanding of these essential microorganisms.