Bacteria and Viruses

1
Bacteria and Viruses
2
Bacteria

• Bacteria are microscopic, unicellular
  (one-celled) organisms that lack a nuclear
  membrane
• Bacteria can live on land, in water, and in the
  air
• They also live in and on both living and dead
  plants and animals
• Most bacteria are heterotrophs.
• Heterotrophs are organisms that cannot make their
  own food

3
(No Transcript)
4
Shapes of Bacteria

• Coccus - round or sphere shaped
• Bacillus rod shaped
• Spirillum spiral shaped

5
Structure of Bacteria

• A bacterium is made up of a thick cell wall
  that encloses and protects cellular material

6
Bacterial Nutrition

• Some bacteria live separately and others remain
  together to form colonies
• Colonies are large groups of bacteria

7
Bacterial Nutrition

• There are bacteria that live as parasites
• A parasite absorbs food materials from other
  living organisms called their hosts
• Others digest and absorb food materials from dead
  organisms
• These bacteria are called saprophytes

8
Beneficial Bacteria

• Most bacteria are beneficial (helpful) to humans
• Bacteria are decomposers that cause decay
• Decomposers are organisms that break down dead
  organisms and return the nutrients to the soil

9
Beneficial Bacteria

• Many bacteria are used to produce food and
  life-saving drugs
• Bacteria are used to make cheese, pickles,
  yogurt, vinegar, and sauerkraut

10
Beneficial Bacteria

• By using methods of gene transplanting, bacteria
  have been encouraged to produce substances such
  as insulin

11
Beneficial Bacteria

• The human intestinal tract contains millions of
  bacteria
• Many of these bacteria help the digestive process
  and others produce vitamins

12
Beneficial Bacteria

• Bacteria are also used in the tanning of leather,
  the curing of tobacco, and the production of food
  for feeding cows

13
Harmful Bacteria

• Some bacteria are not beneficial to man
• Bacteria spoil food by secreting enzymes into
  the food causing it to rot
• Along with enzymes, other substances produced by
  bacteria are released into the food
• Some of these substances are toxic, making the
  food poisonous to humans and other organisms

14
Harmful Bacteria

• Bacteria in large numbers can pollute (dirty)
  lakes, streams, and drinking water
• During respiration, bacteria reduce the
  dissolved oxygen content in water supplies

15
Harmful Bacteria

• Many bacteria are pathogenic
• A pathogen is an organism that causes disease
  and/or infection
• Some bacterial diseases of humans are
  tuberculosis, tetanus, and strep throat

16
Controlling Harmful Bacteria

• Antiseptics, disinfectants, and antibiotics are
  used to control pathogenic bacteria
• An antibiotic is a chemical that can stop the
  growth of some bacteria
• Bacteria are able to produce types that are
  resistant to certain antibiotics
• When this happens, new antibiotics must be
  developed.

17
Controlling Harmful Bacteria

• Bacteria can also be killed in foods by
• pasteurization
• canning
• chemical preservatives
• radiation
• steam/pressure
• salt curing
• dehydration (drying)

18
Harmful Anaerobic Bacteria

• Some bacteria can live anaerobically and cause
  botulism
• A dangerous type of food poisoning, in foods that
  have not been properly canned

19
Harmful Anaerobic Bacteria

• Two other anaerobic bacteria can cause venereal
  diseases
• Gonorrhea (causes sterility)
• Syphilis (can result in death)
• A venereal disease is a contagious disease that
  a person gets through sexual contact
• Both diseases can be treated successfully by
  antibiotics if detected early enough

20
Viruses

• A virus is not a cell
• It is made up of genetic material inside a
  protein coat
• Viruses do not carry on most metabolic
  activities

21
Viruses

• They can only reproduce inside a living cell
  called the host cell
• Outside the host cell, a virus is lifeless
  and often exists as a crystal
• A virus has no means of locomotion

22
Virus Reproduction
23
(No Transcript)
24
Negative Virus Influences

• They cause infections in both plants and animals
• Some viruses cause tumors and warts
• They also destroy cells and are responsible for
  human diseases such as
• polio
• measles
• mumps
• influenza
• hepatitis
• colds
• AIDS

25
Influenza Virus - Flu
Human Papilloma Virus - Warts
Human Immunodeficiency Virus AIDS
Rabies Virus
26
Positive Virus Influences

• Certain viruses are used in the control of
  insect pests
• Others are used in genetic research
• Scientists have been able to use viruses to
  biologically control caterpillars of the European
  pine sawfly and the gypsy moth