Lecture 2 Microbial Evolution Quiz PDF

Stage 1 Fundamentals of Microbiology BIO1314 Dr Linda Stewart L EC T U R E 2 – M I CROBI A L...

Stage 1 Fundamentals of Microbiology BIO1314 Dr Linda Stewart L EC T U R E 2 – M I CROBI A L E VOLU T ION Recommended reading Chapter 1.1, 1.2 Microbiology When we think of microorganisms we immediately think of disease Majority of microorganisms are beneficial to us and the planet Of all known species 87% are beneficial 10% are opportunistic pathogens (cause diseases only under certain conditions) Only 3% are true pathogens  What is a microorganism? Microorganisms are: 1. Organisms and acellular entities too small to be clearly seen by the unaided eye.  Generally, 700 µm in diameter ◦ Most cultured rod-shaped bacteria are between 0.5 and 4.0µm wide and 200 µm in diameter Some very large prokaryotes. Cell Size – Shape Relationship Surface-to-volume ratios, growth rates, and evolution Advantages to being small ◦ Cells want a high surface area-to-volume ratio (S/V ratio). Small cells have more surface area relative to cell volume than large cells (i.e., higher S/V ratio) ◦ How fast a cell grows depends on the rate of nutrient exchange per unit cell volume. Small cells tend to grow faster than larger cells. Increased efficiency of nutrient uptake and diffusion of molecules within a cell. ◦ Large size and odd shape may be protective mechanisms from predation Lower limits of cell size ◦ Cellular organisms