3.01 Bacteria Basics
Microbio review for the USMLE Step 1 Exam:
- Bacteria are single-celled organisms that can cause infection
- Structural components of bacteria include: capsule, cell wall, flagella, fimbriae, plasma membrane, ribosomes, endospores, and DNA
- Capsules help bacteria evade the immune system by inhibiting phagocytes
- Flagella are tail-like appendages that allow bacteria to move, fimbriae help bacteria adhere to surfaces
- Most bacteria have a cell wall, which can be either gram positive or gram negative
- Plasma membrane is composed of proteins and phospholipids and performs various functions
- DNA is the genetic material, ribosomes are used to build proteins, some bacteria have endospores which are heat-resistant resting cells
- Bacteria can be classified by cell wall composition, morphology, metabolism, and based on their ability to grow at different temperatures and pH levels
- Gram staining is a laboratory technique used to differentiate between gram positive and gram negative bacteria
- Morphology of bacteria includes cocci (spherical), bacilli (rod-shaped), and spirilla (spiral-shaped)
- Metabolism of bacteria can be aerobic (uses oxygen) or anaerobic (doesn't use oxygen)
- Temperature and pH ranges at which bacteria can grow vary widely, some can grow at extreme conditions
- Pathogenic bacteria cause disease, while non-pathogenic bacteria do not
- Bacteria can be treated with antibiotics, but overuse can lead to antibiotic resistance
