1. Bacteria and Viruses
Biology
Chapter 10

2. Kingdom Monera Divided now into
Kingdom Archaebacteria
Kingdom Eubacteria
Outnumber all other living organisms combined
Microscopic times smaller than most human cells
Exist EVERYWHERE!
100-20,000 in every cubic meter of air

3. Classification and Morphology
Microbiology – the study of microscopic organisms
Bacteria – all prokaryotic – lack nucleus
Pathogenic – disease causing (minimal)
Decomposer – breaking down of substances

4. Kingdom Archaebacteria
Live in extreme conditions.
Thermoacidophiles – highly acidic soils and hot springs (230 degree F)
Methanogens – live anaerobic conditions producing methane gas as waste
Halophiles – salt-loving; live in extremely salty conditions; metabolize salt to produce ATP

5. Kingdom Eubacteria Largest of the two bacteria kingdoms
Scientists are continuing to fight over the organisms contained in this kingdom.
Most live in non-extreme environments.

6. Bacterial Shapes, Sizes, and Colonies
Shape and Size
Coccus – spherical (~1um diameter); a period could easily have 5,000 coccus lined up across its diameter
Bacillus – rod (~1 um in width and 2-10 um in length)
Spirillum – spiral or corkscrew shape (slightly longer than bacillus)

7. Colonies – unicellular but living together
Diplo – two cells joined together
Strep – joined end-to-end in long chains
Streptococcus
Streptococcus pneumoniae
Staph – clustered together like grapes
Staphylococcus

8. Bacteria Cell Walls and Capsules
Plasma membrane phospholipid bilayer which controls the flow of substances into and out of the cell
Cell wall directly outside the plasma membrane; no cellulose; maintain shape of cell
Capsule – outside cell wall; made of sticky carbohydrates; protects the cell from dry spells

9. Bacterial Cytoplasmic Structures
Nuclear area - DNA material appears as a circular chromosome
Plasmid – one or more smaller circular DNA chromosomes; carry only a few nonessential genes
Mesosomes – twisted invaginations of the plasma membrane supplying additional surface area for metabolic processes to occur

10. Bacteria Locomotive Structures
Flagella – long threadlike whip
Bacteria without flagella appear to vibrate back and forth as water molecules bump into them; can also appear to migrate with the flow of the liquid
A.k.a – Brownian movement

11. Bacterial Reproduction and Growth
Bacteria grow to full size and divide every 30 minutes; over 1 billion bacteria is 15 hours; under 24 hours the cells would weigh over 2000 tons
Growth rate this fast cannot be sustained for long

12. Asexual Reproduction Simple Binary Fission
DNA replicates
Plasma membrane has an invagination and forms two daughter cells
Can be completed in 9 minutes

13. Bacteria and Nutrition
Autotrophs
Photosynthetic – similar but uses different light wavelengths
Chemosynthetic – involves converting inorganic compounds to other usable forms and capturing the energy
Heterotrophic – vast majority; digesting organic substances
Parasitic – feeding on a living host
Saprophytic – feeding on dead organic matter

14. Conditions for Optimal Growth
Moisture – all require moisture to grow; capsule maintains internal moisture
Temperature – ideally normal is around degree F
pH – most bacteria prefer a neutral condition
Nutrition – heterotrophs must obtain energy as well as materials necessary for bacterial biosynthesis

15. Optimal Growth
Bacteria are very environmentally specific; what is beneficial to one may kill another
If conditions turn unfavorable then the bacteria create an endospore.
Endospore – one or more layers of hard material that form around the nuclear area to protect the DNA from the environment; when favorable conditions return the endospore will weaken and the bacteria will break out

16. Bacteria and Oxygen
Obligate anaerobes – organisms that grow only in the absence of oxygen
Obligate aerobes – organisms that grow only in the presence of oxygen
Facultative anaerobes – organisms that can grow with or without oxygen

17. Bacteria and the Transfer of Genetic Material
Conjugation – the bacteria line up side by side and a tube is formed that connects the two; genetic material is passed in one direction
Transformation – living bacterial cells take up other bacteria’s free DNA from nonencapsulated bacteria
Transduction – transfer of genetic material by way of a virus called a bacteriophage

18. Terminology Microbiologist Bacteria Decomposer organism
Thermoacidophile
Methanogen
Halophile
Coccus
Bacillus
Spirillum
Capsule
Nuclear area
Plasmid
Mesosome
Chemosynthetic
Parasitic
Saprophytic
Endospore
Obligate anaerobe
Obligate aerobe
Facultative anaerobe
Conjugation
Transformation
Transduction
Heterotroph
Autotroph
Brownian movement

19. Viruses Virology – the study of viruses
Viruses contain two basic parts:
Core – either DNA or RNA (never both)
Capsid – a protein covering
Envelope – only some have it; made of lipids
Virion – entire virus unit
Obligate intracellular parasites – must have host for life

20. Classifying Viruses Two large groups: Also classified by:
DNA containing or RNA containing; then whether the DNA or RNA is single or double stranded
Also classified by:
Shape
Presence or absence of an envelope
Method of infecting and replicating within the host cell

21. Viroids and Prions
Viroid – smaller than a virus; a short single strand of circular RNA; no capsid or envelope
Prion – smaller than a viroid; abnormal form of a protein; does not contain any nucleic acids

22. Vaccinations
Typically a small dose of the actual virus in a weakened condition.
Allows the body to build up an immunity for the disease.

23. Viral Replication
Virulence – the ability of a pathogen to affect cells
Lytic cycle – the activity cycle of a virulent virus

24. Lytic Cycle Lytic cycle has five stages:
Attachment – virus attaches to host cell
Entry – virus core is injected into the host cell
Replication and transcription – using the cell’s enzymes and organelles, the virus begins to produce multiple copies of the viral nucleic acid
Assembly – the virus proteins form capsids around the replicated viral DNA or RNA forming new virions
Release – lysis occurs and the virions are released into the organism to attach to new host cells and repeat the lytic cycle.

25. Lytic vs. Lysogenic Cycles
The lytic cycle begins to destroy the host cell upon entry.
The lysogenic cycle allows the virus to remain dormant within the host cell and is duplicated when the cell undergoes mitosis thereby creating a whole population of cells that contain the virus. Once the virus is stimulated it enters the lytic cycle and destroys the host cell; after stimulus it returns to dormancy.

26. Viral Diseases VERY specific regarding the host cell.
Diseases are controlled through vaccinations.

27. Disease Terminology
Pathogen – an agent that invades the body and causes a disease
Incubation period – the time between being infected and the first appearance of a symptom
Communicable disease – a disease that can be spread from one person to another by either direct or indirect means
Vector – insects or other arthropods that carry pathogens from one host organisms to another
Carrier – a healthy-appearing individual can spread the disease to others but have no symptoms themselves

28. Structural defenses – prevent pathogens from entering the body
Nonspecific defenses – internal responses to the presence of a pathogen
Specific defenses – chemotherapy directed toward a specific pathogen

29. Disorders – afflictions not caused by a pathogen
Inherited
Injuries
Organic
Tumor – a group of non-functioning cells that grow a different structure
Benign – tumor is slow growing and localized
Malignant – tumor grows rapidly and chaotic
Metastasize – separate from parent tumor and travel