Chapter 19Chapter 19

Bacteria and Bacteria and VirusesViruses

I. ProkaryotesI. Prokaryotes

A.A. Prokaryotes: single-celled Prokaryotes: single-celled organisms that lack a organisms that lack a nucleusnucleus

1. Eubacteria – walls contain 1. Eubacteria – walls contain peptidoglycanpeptidoglycan (a carbohydrate) (a carbohydrate)

2. Archaebacteria – lack 2. Archaebacteria – lack peptidoglycan, DNA similar to peptidoglycan, DNA similar to eukaryoteseukaryotes

B.B. Identifying ProkaryotesIdentifying Prokaryotes

1. Shapes1. Shapes

a. Bacilli (a. Bacilli (rodrod shaped) shaped)

b. Cocci (b. Cocci (sphericalspherical))

c. Spirilla (c. Spirilla (spiralspiral))

2. Cell Walls2. Cell Walls

a. Gram-a. Gram-positivepositive (with peptidoglycan) (with peptidoglycan) – purple– purple

b. Gram-b. Gram-negativenegative (without (without peptidoglycan) – red peptidoglycan) – red

Which bacteria is rod shaped and has peptidoglycan in its cell walls?

This one?NO…it has spheres!

This one?NO…it has spheres!

This one?NO….why?

This one?Yes!

3. Arrangement3. Arrangement

a.a. Staphyl: Staphyl: ClumpsClumps or clusters or clusters

b.b. Strepto: long chains Strepto: long chains

4. Movement 4. Movement

a.a. Propelled by tail-like structure called Propelled by tail-like structure called flagellaflagella

b.b. Glide along a Glide along a slimeslime secretion secretion

c.c. Move along like Move along like snakessnakes

d.d. Some Some do notdo not move move

C.C. Obtaining EnergyObtaining Energy

1. Autotrophs1. Autotrophs

a. a. Photoautotrophs: obtain Photoautotrophs: obtain energy energy from from photosynthesisphotosynthesis

b. b. Chemoautotrophs: obtain Chemoautotrophs: obtain energy energy from inorganic from inorganic moleculesmolecules

2. Heterotrophs2. Heterotrophs

a. Can cause a. Can cause foodfood poisoning poisoning

b. Photoheterotrophs: b. Photoheterotrophs: photosynthetic, photosynthetic, but also need but also need organicorganic compounds compounds for nutrition for nutrition

D.D. Releasing EnergyReleasing Energy

1. Obligate aerobes: require 1. Obligate aerobes: require oxygenoxygen

2. Obligate anaerobes: cannot live in 2. Obligate anaerobes: cannot live in presencepresence of oxygen of oxygen

3. Facultative anaerobes: do not 3. Facultative anaerobes: do not needneed oxygen, but can live in the presence oxygen, but can live in the presence of itof it

E.E. Growth and ReproductionGrowth and Reproduction

1. Binary fission: cell divides, 1. Binary fission: cell divides, asexualasexual

2. Conjugation: transfer of genetic 2. Conjugation: transfer of genetic information from one cell to another, information from one cell to another, sexualsexual

3. In unfavorable conditions, many 3. In unfavorable conditions, many bacteria can form bacteria can form endosporesendospores – can – can remain remain dormantdormant for months or years for months or years

II. Bacteria in NatureII. Bacteria in Nature

A.A. DecomposersDecomposers

1. Help recycle nutrients – break down 1. Help recycle nutrients – break down deaddead organisms organisms

2. Used in sewage treatment2. Used in sewage treatment

B.B. Nitrogen FixersNitrogen Fixers

1. Nitrogen fixation: converting nitrogen 1. Nitrogen fixation: converting nitrogen into a into a formform plants can use plants can use

2. 2. RhizobiumRhizobium grow on roots of grow on roots of soybeans and other legumes soybeans and other legumes

– – converts converts nitrogennitrogen to ammonia to ammonia for the for the plant plant

Nitrogen-fixing bacteria Rhizobium on the roots of the broad bean plant Vicia faba.

The roots of the host plant become infected with the bacteria as seedlings, and respond by surrounding the bacteria with root hairs. The relationship between a particular host species and a particular bacterium is highly specific, and is regulated by a series of recognition events that prevent the wrong species of bacterium from taking up residence in the wrong plant.

C.C. Bacteria and DiseaseBacteria and Disease

1. Pathogen: disease-causing 1. Pathogen: disease-causing agentsagents

2. 2 ways bacteria cause disease2. 2 ways bacteria cause disease

a. Break down a. Break down tissuestissues for food for food

b. Release b. Release toxinstoxins

3. Many can be prevented with 3. Many can be prevented with vaccines; many can be treated vaccines; many can be treated

with with antibioticsantibiotics

D.D. Human Uses of BacteriaHuman Uses of Bacteria

1. Food – cheese, 1. Food – cheese, yogurtyogurt, buttermilk, , buttermilk, sour cream, pickles, sauerkrautsour cream, pickles, sauerkraut

2. Industry – cleaning up oil spills, 2. Industry – cleaning up oil spills, mining minerals, synthesizing mining minerals, synthesizing drugsdrugs

3. Bacteria live in our digestive tract to help 3. Bacteria live in our digestive tract to help in in digestiondigestion (called normal flora) (called normal flora)

Billions of bacteria live in each of us. If we could weigh all the bacteria in the gastrointestinal tract, it would amount to about three and one-half pounds.

E.E. Controlling BacteriaControlling Bacteria1. Sterilization: destroy bacteria by 1. Sterilization: destroy bacteria by

subjecting them to great heat or subjecting them to great heat or chemicalschemicals

a. Boiling, frying, steaming a. Boiling, frying, steaming can all can all killkill bacteria bacteria

b. Disinfectant chemical b. Disinfectant chemical solutions solutions can be used in homes can be used in homes and and hospitalshospitals2. Refrigeration – bacteria grow slowly 2. Refrigeration – bacteria grow slowly at at lowlow temperatures temperatures

III. VirusesIII. Viruses

A.A. Viruses: particles of nucleic acid and Viruses: particles of nucleic acid and proteinprotein

1. Nucleic acid = DNA or RNA that 1. Nucleic acid = DNA or RNA that contains instructions for making contains instructions for making new new copies of the copies of the virusvirus

2. Capsid: outer protein 2. Capsid: outer protein coatcoat

B.B. Viral InfectionViral Infection

1. Infect cells and 1. Infect cells and replicatereplicate inside host inside host cellcell

2. Bacteriophage: 2. Bacteriophage: virusesviruses that infect that infect bacteria bacteria

3. 2 types of viral infections3. 2 types of viral infections

a. Lytic infection: virus enters cell, a. Lytic infection: virus enters cell, make copies of itself and causes make copies of itself and causes

the the cell to cell to burstburst

b. Lysogenic infection: virus embeds b. Lysogenic infection: virus embeds its DNA into DNA of host and is its DNA into DNA of host and is replicatedreplicated with host cell’s DNA with host cell’s DNA

C.C. Viruses and DiseaseViruses and Disease

1. Many viruses can be prevented 1. Many viruses can be prevented through the use of vaccines (polio, through the use of vaccines (polio,

measles, measles, influenzainfluenza))

2. Oncogenic viruses cause 2. Oncogenic viruses cause cancercancer

3. Retroviruses contain 3. Retroviruses contain RNARNA

4. Prions contain no DNA or RNA, only 4. Prions contain no DNA or RNA, only proteinprotein

poliopolio

MeaslesMeasles

Regulation of cell cycles is of key Regulation of cell cycles is of key importance in human papilloma importance in human papilloma virus (HPV)-associated cervical virus (HPV)-associated cervical

carcinogenesiscarcinogenesis

RetrovirusesRetroviruses

HIV

PrionsPrions

Mad cow disease

QUIZ QUIZ

Next class!Next class!