Finals_Ubiquity of Microbes Flashcards
Who studied bacteria in his labo- ratory, one of the first challenges was to devise a method to grow bacteria in culture so that populations could be separated into individual species
Robert Koch
most widely distributed organisms in the biosphere.
Bacteria
visible mass of cells usually resulting from the division of a single cell
colony
Identify how to record amount of colonies on petri dish
- no growth
0
Identify how to record amount of colonies on petri dish
- 1 to ten colonies
+
Identify how to record amount of colonies on petri dish
- 11 to 50 colonies
++
Identify how to record amount of colonies on petri dish
- 51 to 100 colonies
+++
Identify how to record amount of colonies on petri dish
- over 100 colonies
++++
In what ways do the macroscopic features of bacterial colonies differ from those of molds?
molds are characteristically fuzzy due to their long hyphae, bacterial colonies are more often smooth in appearance.
Why is the level of contamination measured as number of colonies rather than size of colonies?
Number of colonies tells you how many bacterial cells were present while the size is just a growth characteristic.
Should one be concerned to find bacteria on the skin? How about molds?
Finding bacteria and mold on human skin is normal as they are part of the natural microbiome. Concern arises if there is an imbalance or overgrowth which can lead to infections.
How can microbial levels be controlled on the skin?
Hand Hygiene
Antimicrobial Products
Proper Wound Care
Personal Hygiene
How can microbial levels be controlled in the air?
Air Filtration
Ventilation
Humidity Control
Air Purifiers
How can microbial levels be controlled on the surfaces in the environment?
Cleaning
Disinfection
Surface Coatings
Bacteria vs Eukaryotic Microorganisms_Size
Bacteria:
Typically smaller than eukaryotic cells, ranging from about 0.2 to 2.0 micrometers in diameter.
Eukaryotic Microorganisms:
Generally larger, usually ranging from 10 to 100 micrometers in diameter. This group includes fungi, protozoa, and algae.
Bacteria vs Eukaryotic Microorganisms_Organization of Genetic Material
Bacteria:
- Genetic material is usually a single circular chromosome located in the nucleoid, a region within the cell.
- Plasmids (small, circular, extra-chromosomal DNA) are common.
Eukaryotic Microorganisms:
- Genetic material is organized into multiple linear chromosomes contained within a membrane-bound nucleus.
- Additional genetic material may be present in organelles such as mitochondria and chloroplasts.
Bacteria vs Eukaryotic Microorganisms_Ribosomes
Bacteria:
Contain 70S ribosomes (composed of 50S and 30S subunits).
Eukaryotic Microorganisms:
- Contain 80S ribosomes (composed of 60S and 40S subunits) in the cytoplasm.
- 70S ribosomes are present in mitochondria and chloroplasts.
Bacteria vs Eukaryotic Microorganisms_Cell Wall
Bacteria:
- Most have a cell wall composed of peptidoglycan (murein).
- Gram-positive bacteria have thick peptidoglycan layers, while Gram-negative bacteria have thin peptidoglycan layers and an outer membrane.
Eukaryotic Microorganisms:
- Fungi have cell walls composed of chitin.
- Algae have cell walls made of various polysaccharides, including cellulose.
- Protozoa generally lack a rigid cell wall but may have a flexible pellicle.
Bacteria vs Eukaryotic Microorganisms_Respiration and Photosynthesis
Bacteria:
- Respiration can be aerobic or anaerobic, occurring in the cytoplasm and across the cell membrane.
- Photosynthesis occurs in photosynthetic bacteria (e.g., cyanobacteria) and involves specialized structures like thylakoids.
Eukaryotic Microorganisms:
- Aerobic respiration occurs in mitochondria.
- Photosynthesis (in algae and some protists) occurs in chloroplasts, which contain chlorophyll and other pigments.
Bacteria vs Eukaryotic Microorganisms_Motility Mechanisms
Bacteria:
- Use flagella (simple, composed of a single type of protein, and rotary motion).
- Some use pili (for twitching motility) or gliding mechanisms.
Eukaryotic Microorganisms:
- Use complex flagella or cilia (composed of microtubules in a 9+2 arrangement, with a whip-like motion).
- Some move by amoeboid movement using pseudopodia (extensions of the cell membrane and cytoplasm).
