16.1 - Bacteria
1) Bacteria have successfully colonized almost every habitat on Earth
2) Bacteria have been successful due to:
> their rapid rate of cell division
> their protective mechanisms
> their diversity of nutritional sources.
3) Bacteria are the oldest group of organisms on Earth.
4) Bacteria are much smaller than eukaryotic cells.
5) Special dyes are used to determine if bacteria is Gram-negative or Gram-positive.
> Gram-negative bacteria stain pink
> Gram-positive bacteria stain purple
6) Bacteria are prokaryotes.
>They lack membrane-bound organelles and chromosomes that are found in eukaryotes.
>They do have ribosomes, cytoplasm, and one molecule of DNA.
7) Bacteria obtain energy in one of 3 ways ... by:
> photosynthesis - some produce “food” from the sun’s energy (light)
> chemosynthesis - complex organic molecules are produced from the energy in inorganic molecules
> heterotrophic nutrition - some must “eat” nutritients found in the environment
16.2 - How Bacteria Affect Humans
1) Some bacteria are helpful.
a) Decomposing bacteria are nutrient recyclers.
b) Nitrogen-fixing bacteria enrich the soil by adding nitrogen
c) Some bacteria are used to manufacture food and drugs.
> Bacteria is used to make sauerkraut, pickles, ice cream, buttermilk, yogurt, cheese, etc.
> Bacteria are used to make insulin and in other drugs/medical products.
2) Some bacteria are harmful.
a) Bacteria can cause diseases.
Some examples of bacteria-caused diseases are tuberculosis, diphtheria, scarlet fever, bubonic plague, typhus, tetanus, cholera, typhoid, leprosy, and lyme disease.
b) Bacteria can cause food poisoning.
3) A pathogen is a disease-causing agent. Pathogenic bacteria are harmful because they damage their host’s tissues.
4) Harmful bacteria can be controlled by:
a) proper sanitation & good hygiene
b) temperature treatments
> Applying high temperatures to food (called pasteurization) kills bacteria.
> Cold temperatures slows down the growth of bacteria.
> Antibiotics are antibacterial drugs.
> Alexander Fleming discovered the first antibiotic, penicillin, in 1928.
> Vaccinations help the body’s immune system resist infection
> A harmless version of the pathogen or its toxin is put into the body.
> The body learns how to “defeat” the pathogen by destroying the harmless version.
> When the actual pathogen is encountered, the body then knows how to destroy it.
16.3 - Viruses
1) Viruses are small, simple particles that invade living cells.
> The inside is a nucleic acid core (RNA or DNA).
> The outer covering is a protein coat.
> Some viruses ahve a layer of lipids over the protein coat.
2) Viruses are not considered living organisms.
> They are not made up of cells.
> They cannot use energy.
> They can only reproduce when inside living cells.
> BUT, they do have genetic material and can evolve.
3) Viruses reproduce by taking control of a host cell, where new virus particles are assembled.
4) Viruses cause many diseases, such as AIDS, smallpox, polio, flu, measles, mumps, and colds.
5) Vaccinations can protect you from certain viral diseases.
6) Some viruses change rapidly, so it is hard to make a vaccine to combat the many forms.