Microbes Flashcards
Name four categories of microbes.
Bacteria, viruses, prions, and other organisms (such as fungi, multicellular parasites, and single-celled protistans.
Microbes
Microbes are microscopic organisms and particles.
Pathogens
Microbes that cause disease in humans
Give three positive uses of microbes.
Microbes can be used to make many foods, drugs, and they are important as decomposers to recycle nutrients.
Describe bacteria.
Bacteria are single-celled, prokaryotic organisms. Almost all have a cell wall, and have DNA in a single chromosome - no nucleus. Some have plasmids. They have ribosomes, and reproduce by binary fission.
Plasmids
Accessory rings of DNA in bacterium
What does reproduction by binary fission result in?
Reproduction by binary fission results in 2 cells that are identical to the original cell.
What can be used to combat pathogenic bacteria?
Antibiotics can interfere with reproduction and survival of bacteria.
Name the three shapes of bacteria, and the words that describe the shape.
Sphere-shaped - “coccus”
Rod-shaped - “bacillus”
Curve-shaped - “spirillum”
Describe viruses.
Viruses are small, nonliving obligate parasites. They are acellular (not composed of cells). They all have an outer protein coat called a capsid and nucleic acid (RNA or DNA) inside. Some also have an envelope.
Why are viruses considered nonliving?
Viruses are considered nonliving because they cannot reproduce by themselves, and must reproduce inside of a host cell.
Capsid
The outer protein coat on a virus
Do antibiotics work against viruses?
No, because antibiotics affect the reproduction of their target, and viruses don’t reproduce on their own - they hijack host cells, which we don’t want to target.
What does the damage from a virus depend on?
The damage from a virus depends on the efficiency of the immune system and the ability of the infected tissue to repair itself (e.g. common cold - respiratory track - versus polio - nerve cells)
Prions
Infectious protein particles. They occur when normal proteins change shape.
What do prions cause?
Prions cause degenerative disease of the nervous system, calcified plaque.
Epidemiology
The study of diseases in populations
Infectious Diseases
Diseases caused by pathogenic microbes, including bacteria, viruses, prions, fungi, parasites, and protozoans
Epidemic
More cases of the disease than expected in a certain area for a certain period.