Bacteria Characteristics and Types

Study Notes

Gram-positive: Thick peptidoglycan layer in cell wall, stain purple
Gram-negative: Thin peptidoglycan layer, outer membrane, stain pink
Spiral (e.g., Spirillum): Helical shape, often found in aquatic environments
Rod-shaped (e.g., E. coli): Straight or curved, common in soil and human gut
Spherical (e.g., Staphylococcus): Round shape, often found in skin and respiratory tract

Binary fission: Cell division, resulting in two identical daughter cells
Generation time: Time required for population to double in size
Nutrient requirements: Carbon, nitrogen, phosphorus, and other elements for growth
Environmental factors: Temperature, pH, oxygen, and light affect growth and survival

Symbiotic relationships: Mutualism (e.g., gut bacteria), commensalism, or parasitism
Pathogenesis: Ability to cause disease in hosts (e.g., Salmonella, Streptococcus)
Antibiotic resistance: Development of mechanisms to evade antibiotic effects
Biofilm formation: Adhesion to surfaces, forming complex communities

Lack true nucleus and membrane-bound organelles, making them prokaryotic cells
Typically 0.5-5.0 μm in diameter, being single-celled organisms
Possess a rigid cell wall outside the cell membrane, providing shape and support
Have whip-like flagella structures used for movement

Gram-positive bacteria have a thick peptidoglycan layer in their cell wall and stain purple
Gram-negative bacteria have a thin peptidoglycan layer, an outer membrane, and stain pink
Spiral bacteria, such as Spirillum, have a helical shape and are often found in aquatic environments
Rod-shaped bacteria, like E. coli, are straight or curved and common in soil and the human gut
Spherical bacteria, such as Staphylococcus, have a round shape and are often found in skin and the respiratory tract

Bacteria reproduce through binary fission, resulting in two identical daughter cells
The generation time is the time required for the population to double in size
Bacteria require carbon, nitrogen, phosphorus, and other elements for growth
Environmental factors like temperature, pH, oxygen, and light affect growth and survival

Aerobic bacteria, such as Pseudomonas, use oxygen for energy production
Anaerobic bacteria, like Clostridium, do not use oxygen for energy production
Fermentation is the process of breaking down organic compounds to produce ATP and byproducts
Nitrogen-fixing bacteria convert atmospheric nitrogen into usable forms

Symbiotic relationships can be mutualistic, commensalistic, or parasitic
Pathogenic bacteria, like Salmonella and Streptococcus, have the ability to cause disease in hosts
Antibiotic resistance occurs when bacteria develop mechanisms to evade antibiotic effects
Biofilm formation involves the adhesion of bacteria to surfaces, forming complex communities