1. Ch 19- Bacteria and Viruses
Prokaryote- unicellular organisms that lacks a nucleus
How do the two groups of prokayotes differ?
Make up of cell walls
Archaebacteria lack peptidoglycan, have different membrane lipids
DNA sequence is more like eukaryotes than eubacteria
Thought to be ancestors of eukaryotes
Eubacteria live almost everywhere and archaebacteria live in extremely harsh environments
What factors are used to identify prokaryotes?
Shape
Chemical nature of their cell walls
Movement
How they obtain energy

2. Identifying Prokaryotes
Shapes
Bacilli are rod shaped
Cocci are spherical shaped
Spirilla are spiral and corkscrew shaped
Cell walls- gram staining to tell apart
Gram positive- thick peptidoglycan walls, appear violet
Gram negative- thinner walls, appear pink or light red
Movement- some move and some don’t
Flagella- whiplike structures used for movement

3. Metabolic Diversity
Heterotrophs- consume organic molecules made by other organisms
Chemoheterotrophs- take in organic molecules
Photoheterotrophs- photosynthetic and take in organic compounds for carbon source
Autotrophs- produce own food
Photoautotrophs
Chemoautotrophs- do not require light, use energy from chemical reactions

4. Growth and Reproduction
Binary fission- form of asexual reproduction where cell doubles in size, replicates DNA and divides in half, produces two identical daughter cells
Conjugation- the exchanging of genetic information between bacteria
Endospore- forms when growth conditions become unfavorable
Bacterium produces thick internal wall, encloses DNA, remains dormant for months or years

5. Importance of Bacteria
What is the importance of bacteria?
Vital to maintaining living world
Producers and decomposers
Decomposers recycle nutrients
Nitrogen fixation- converting nitrogen gas into form plants can use
Used in foods and beverages
E. coli break down food in intestines
Bacteria in extreme environments- rich source of heat stable enzymes
Medicine, food production, industrial chemistry

6. Sec 2- Viruses What is a virus? Welcome to Discovery Education Player
Composed of core of DNA or RNA surrounded by protein coat
Reproduce only by infecting living cells
Enter living cells, use infected cell to produce more viruses
Vary greatly in size and structure
Welcome to Discovery Education Player
Capsid- virus’s protein coat
Most are highly specific to cells they infect
Bacteriophages- viruses that infect bacteria

7. Viral Infection
Lytic infection- virus enters a cell, makes copies of itself, and causes the cell to burst
Injects host cell with viral DNA, mRNA is made by the host cell from viral DNA into viral particles
Lysogenic infection- virus integrates its DNA into the DNA of the host cell
Viral genetic information replicates along with host cell’s DNA
Does not lyse the host cell right away
Prophage- viral DNA that is embedded in the host’s DNA
May stay for many generations

8. Retroviruses Viruses that contain RNA as their genetic information
Produce a DNA copy of their RNA, inserted into DNA of host cell
May remain dormant for lengths of time, directing production of new viruses-cause death of new cell
Responsible for some types of cancer
Acquired immune deficiency syndrome (AIDS)

9. Are viruses alive? Reproduction Regulate gene expression Genetic code
Only within host cell
Regulate gene expression
Genetic code
DNA or RNA
Evolve
Do not………
Grow or develop
Obtain and use energy
Respond to environment
Viruses are completely dependent upon living things

10. Sec 3- Diseases Caused by Bacteria and Viruses
Pathogens- disease-causing agents
How do bacteria cause disease?
Damage the cells and tissues of infected organism directly by breaking down the cells for food
Release toxins or poisons that travel throughout the body interfering with the normal activity of the host
Mycobacterium tuberculosis- causes tuberculosis, destroys lung tissue
Streptococcus- causes strep throat, releases toxins in bloodstream and can cause scarlet fever
Corynebacterium diphtheriae- causes diphtheria, releases toxins into bloodstream that destroy tissue, can lead to trouble breathing, heart failure

11. How to prevent disease?
Vaccine- preparation of weakened or killed pathogens
Prompts body to produce immunity to disease
Immunity- body’s ability to destroy new pathogens
Antibiotics- compounds that block the growth and reproduction of bacteria
Penicillin

12. How can bacterial growth be controlled? How do viruses cause disease?
Sterilization, disinfectants, and food processing
How do viruses cause disease?
Produce disease by disrupting the body’s normal equilibrium
Many attack and destroy certain cells in body
Cause symptoms of disease
Poliovirus
Other cause cells to change patterns of growth and development
Cannot be treated with antibiotics

13. Prions- protein infectious particles, contain no DNA or RNA
Viruses in animals
Foot-and-mouth disease infected cattle, sheep, and pigs in Europe in late 90’s
Viruses in plants
Tobacco mosaic virus
Difficult with cell walls
Viroids- single stranded RNA molecules that have no surrounding capsids
Prions- protein infectious particles, contain no DNA or RNA
May be cause of mad cow disease