Bacteria and Viruses Ch. 19

Bacteria: They’re everywhere!

Size of Bacteria Coin 1cm in diameter Size of bacteria 1-5 micrometers ,000 bacteria lined up Penny 1.9 cm: How many bacteria IN A LINE? Quarter 2.5 cm?

DNA arrangement in Prokaryotes What is this circular DNA called? Plasmid Prokaryotes do not have an organized nucleus or organelles.

Classifying Prokaryotes Eubacteria (true bacteria) –cell wall contains the carbohydrate, peptidoglycan. Archaebacteria (ancient bacteria)- lack peptidoglycan in cell walls and have different membrane lipids. The DNA sequences of key archaebacteria are more like those of eukaryotes than eubacteria. They live in harsh environments.

Identifying Prokaryotes Shape –Rod (bacilli) –Spiril (spirilla) –Circluar (cocci) –Chain (strepto) –Cluster (staphlo) Movement - flagella, slide, non moblie, swivel Cell Walls –Gram +: thick peptidoglycan wall (purple) –Gram -: thin layer of peptidoglycan inside the lipid bilayer (pink) Examples of pathogenic bacteria

Gram + or Gram – Identify shape

Metabolic Diversity- another way to classify Heterotrophs- can’t make their own food. –Chemoheterotrophs- taken in organic molecules for both energy and a supply of C. US. –Photoheterotrophs- use sunlight for energy, and need to take in organic compounds as C source. Ex: purple non-sulfur bacteria, heliobacteria Autotrophs- make own food –Photoautotrophs- plants photosynthesis –Chemoautotrophs- make organic compounds from CO2. H 2 S vents –Which category do most prokaryotes fall under?

Oxygen or no oxygen? Which of these test tubes show bacteria growing in an anaerobic environment? Why? Which of these show bacteria living in an aerobic environment? Why?

Releasing Energy Obligate aerobes- require oxygen Ex: TB Obligate anaerobes- require no oxygen Ex: Clostridium botulium Facultative anaerobes- do not require oxygen, but are not killed by its presence. Ex: E. coli Which do you think were the first type?

Reproduction How do bacteria reproduce? Binary Fission What type of reproduction is this? asexual What is the end result? Bacteria that are identical to the parent.

Other forms of reproduction Conjugation- hollow bridge forms between two bacterial cells, and genes move from one cell to the other. Spore formation- occurs when growth conditions are unfavorable. An endospore is formed to protect DNA and cytoplasm. When conditions improve, endospore will germinate.

Bacteria Importance Decomposers Nitrogen fixers- convert N into usable form. Rhizobium, nodules on roots of legumes (bean plants) Human uses: –Food, remove waste products, digestion, clean up oil spills.

The bacterial cell What is the flagellum used for? Movement What are the three shapes of bacteria? Cocci, bacillus, spirillum

Bacteria Environments Where do bacteria live? Everywhere, they’re ubiquitous What do we call the bacteria that live in cold temperatures? psycrophiles

What do we call the bacteria that live in hot temperatures? Thermophiles Bacteria that live in very acidic environments are called acidophiles. What do we call those bacteria that live at “normal” temperatures? Mesophiles

Where bacteria grow, where nothing else can. What do we call bacteria that live in swamps? What do they make? Methanotrophs make methane gas. What are bacteria called that live in extreme salt conditions? Halophiles

Viruses Particles of nucleic acid, protein and in some cases lipids. Nucleic acid (DNA or RNA) surrounded by protein capsid that protects the NA. Nonliving

Viral Diversity DNA or RNA Single stranded or double stranded Enveloped (animal) or non-enveloped (plants) Temperate or virulant Symmetry: isohedral (many facets) or helical (round)

Viral Infection Lytic- virus enters a cell, makes copies of itself and causes the cell to burst. Destroys host cell. Lysogenic- virus integrates its DNA into the DNA of host cell, and the viral genetic information replicated indefinitely along with the host cell’s DNA. Prophage- viral DNA that is embedded in the host’s DNA.

Retroviruses Contain RNA. Produce a DNA copy of their RNA and insert it into the DNA of host cell. RNA  DNA using reverse transcriptase. (RT) AIDS

Vector Viruses must have a vector or living host in order to grow and reproduce. –Deer tick and Lyme Disease, mosquito and Malaria Viruses are much smaller than bacteria.

Pathogens Viruses or organisms that causes an infectious disease. Ex: viruses, bacteria, protists, fungi, roundworms and flatworms. Bacteria- some produce toxins Virus- chicken pox, cold Protists and roundworms- destroy body tissue by feeding on and burrowing into the tissue. Fungi- athletes foot, ringworm

Remembering Invaders Antibiotics –Slow down microbial reproduction: bacteria, fungi and protists Vaccinations- Edward Jenner Injections of weakened or killed microbes to enhance immunity –Stimulate development of memory cells

Viroids and Prions Viroids- contain only RNA, but lack an envelope and capsid. Cause problems in potatoes, tomatoes, and fruit trees. Prions- proteins that have the ability to transmit diseases. Protein direct the host to create abnormal proteins that can cause serious neurological disease in animals and humans. Mad Cow Disease Alzheimers ?

Bacteria and Viruses Review Go to the following link and click on your book. Go to Ch. 19 and take the Self-test and review the concepts. Ch. 19 Review Be a microbe detective.