1. Viruses & Bacteria
Chapter 19
Pages

2. Compare/Contrast Prokaryotes (Bacteria) Eukaryotes Smaller Larger
Simpler Complex
Has genetic material Has genetic material
No nucleus Nucleus
Grow, reproduce, & Grow, reproduce, &
respond to environment respond to environment
Some move by gliding All move
or swimming
Some have internal Have internal membranes
membranes
Unicellular Unicellular & multicellular
Has organelles & cytoplasm

3. Bacteria Prokaryotes Smallest, most common microorganism Single-celled
Lack nucleus
Has DNA

4. Bacteria 2 Kingdoms Eubacteria (pg. 472)
live almost everywhere, larger of the two.
Usually surrounded by a cell wall made up of carbohydrate & peptidoglycan.
Cell membrane inside cell wall.
Cytoplasm.
Ex. E coli

5. Bacteria 2 Kingdoms Archaebacteria Look similar.
Live in harsh environments.
Lack peptidoglycan in the cell wall.
Have different membrane lipids.
DNA sequences of key genes are more like those of eukaryotes than eubacteria.
Are thought to be ancestors of eukaryotes.
Ex. Methangones- produce methane gas.

6. Bacteria How we Identify Prokaryotes:
Shape – bacilli, cocci, spirilla.
By the way they move.
By the way they obtain energy.
Most are Heterotrophes which obtain energy by consuming food.
Chemoheterotroph- Ex. Botulism (food poisoning).
Photoheterotroph- uses photosynthesis.
Autotrophs make their own food.
Chemoautotroph- found in deep ocean floors.
Photoautotroph- found near surface in lakes oceans & streams.
The chemical nature of their cell walls.
A method of Gram Staining is used to determine nature. Gram (+) = violet, Gram (-) = pink.

7. Bacteria How we Identify Prokaryotes (cont.):
How they release energy by cellular respiration and fermentation
Obligate aerobes – require constant supply of oxygen. Ex. Tuberculosis.
Obligate anaerobes – do not require oxygen. Oxygen could kill it. Ex. Botulism is found in canned food that’s not properly sterilized.
Facultative anaerobes – can survive with or without oxygen. Can live anywhere. Ex. E coli which is found in the large intestines or in sewage or contaminated water.

8. Bacteria Reproduction
Binary fission – DNA replicates & divides producing 2 daughter cells. Asexual reproduction.
Conjugation – process where genetic information is exchanged.
Spore formation – an endospore may form when growth conditions become unfavorable.

9. Bacteria Importance of Bacteria:
Producers – that carry out photosynthesis.
Decomposers – that break down dead matter “natural recycler”.
Nitrogen fixers – process in which soil bacteria convert natural nitrogen gas into a form plants can use.
Human use – industry (clean up oil spills), food production, synthesize drugs, mine minerals, & remove waste products & poisons from water.
Ex. E coli in intestines make vitamins that the body cannot produce themselves which is a symbiotic relationship (both benefit).

10. Viruses Viruses are particles of: They vary in size and structure.
Nucleic acid
Protein
Lipids (only in some)
They vary in size and structure.
They enter living cels & use the machinery of the infected cell to produce more viruses.
Composed of:
A core DNA or RNA (which has the instructions for making copies)
This is surrounded by a protein coat called a capsid which binds the virus to the surface of the host cell.

11. Viruses Bacteriophages- Viruses that infect bacteria.
Ex. Bacteriophage T4

12. Viruses Once inside a host cell: pg. 481 Lytic infection
Virus inters cell and makes copies of itself.
Causes cell to burst, releasing new virus particales that can attack other cells.
It then uses materials of host cell to make copies of its own DNA molecule.
Host cell is destroyed.
Lysogenic infection
Virus integrates its DNA into the DNA of host cell.
The viral genetic info. replicates along with the host cell’s DNA.
Viral DNA that’s embedded in host’s DNA is called prophage.
Unlike lytic, it does not lyse the host cell right away so it may remain a part of DNA of host for many generations.

13. Viruses Retroviruses contain RNA as their genetic information.
Genetic information is copied backwards.
It may remain dormant for any length of time before becomes active and it can cause death of the host cell.
Ex. AIDS, some cancers.

14. Viruses Must infect living cells in order to reproduce. Are Parasites.
Are not considered to be living things because they are not made up of cells & cannot live independently.
See Chart on pg. 483

15. Diseases Caused by Bacteria & Viruses
Pathogens
Disease- causing agents.
Include bacteria & viruses that cause disease (not all bacteria).
Some live in and on the human body & help it perform essential functions
Chart on pg. 486

16. Bacterial Diseases
Louis Pasteur – the first to show that bacteria caused diseases and established the germ theory of disease.
Diseases:
Tuberculosis- bacteria is inhaled into lungs which destroys tissue and gets into the blood to travel to other places throughout the body.
Strep Throat- bacteria releases toxins. This bacteria also causes scarlet fever.
Diphtheria- infects tissues of the throat which leads to breathing problems, heart failure, paralysis & death.
Lyme Disease
Tooth Decay

17. Bacteria produce disease in 2 ways:
Bacteria damage the cells & tissues of the infected organism directly by breaking down the cells for food.
Bacteria release toxins (poisons) that travel throughout the body interfering with the normal activity of the host.

18. Prevention & Control
Vaccine – a preparation of weakend or killed pathogens. It can prompt the body to produce immunity to the disease.
Immunity – the body’s natural way of killing pathogens.
Antibodies – compounds that block the growth & reproduction of bacteria.
When a bacterial infection occurs, antibiotics can be used to fight the disease.
Animals can suffer from bacterial diseases as well. Ex. Anthrax – sheep to farmers & wool workers which can lead to death. (biological warfare)

19. Viral Diseases Viruses disrupt the body’s normal equilibrium.
Viruses attack & destroy certain body cells causing the symptoms of the disease.
Diseases: Chart pg. 489
Common cold
Influenza
AIDS
Chickenpox
Measles
Can produce other serious diseases in both animals & plants.
Plant viruses have a difficult time entering cells they infect partly because plant cells have though cell walls.

20. Viral Diseases 2 Virus like particles can cause disease:
Viroids – single-stranded RNA molecules that have no surrounding capsoid. (cause disease in plants).
Ex. Tobacco mosaic virus.
Prions – particles that contain only protein which have no DNA or RNA. (cause disease in animals & humans).
Ex. Foot & mouth disease in livestock.

21. Protection Against Vaccines – prevention.
Antibiotics – viruses do not respond to antibiotics but sometime the symptoms can be treated.

22. Prevention & Control Methods of controlling bacterial growth:
Sterilization – heat; most can’t survive high temperatures for long period on time.(kills bacteria)
Disinfectants – soaps & cleaning solutions; sterilizes hospitals; overuse may cause bacteria to evolve.(kills bacteria)
Food storage – refrigeration (bacteria takes longer to multiply at low temperatures); boiling; frying; steaming.
Food processing – canning (heated to high temperature, placed into sterile jars & sealed); chemical treatments such as salt, vinegar,sugar. (kills bacteria)