To Review: Archaebacteria Are prokaryotes Unicellular organisms without nuclei No organelles Have Cell Walls Archaebacteria is the oldest organism. Lacks peptidoglycan. DNA is more similar to eukaryotes, denotes lineage. Live in extreme environments No oxygen (anoxic) Hot Springs, deep ocean Energy: Chemosynthesis

To Review: Eubacteria Are Prokaryotes Unicellular organisms without nuclei Are characterized by … Shape Chemical nature of cell walls The way they move The way they obtain energy No organelles Cell Walls thicker (peptidoglycan, a carbohydrate) Live anywhere Freshwater, saltwater, on land, in the human body Can be heterotrophic, photosynthetic and chemosynthetic

Bacterial Feeding Heterotrophs – take in organic molecules for energy and a supply of Carbon. Chemoheterotrophs – use chemicals for gaining energy. Autotrophs – create their own energy. Photoautotrophs – gain energy from light from the sun to convert CO2 and water into energy Chemoautotrophs – make organic carbon from CO2. Do not require light, but instead use energy from chemical reactions using Ammonia, HS, nitrates, S, and Fe. Live in the deep ocean. In bacterial infections, they harm the host by either destroying cells for food or releasing toxins (poisons) in the host’s body.

Bacterial Reproduction Binary Fission – asexual reproduction Chromosomes are replicated and move to the poles of the cell As the bacterium gets larger, it pinches in between Genetically identical Very fast (every 20 mins) Conjugation – sexual reproduction Through a pilus (pili) exchange genetic information Not genetically identical Creates new genetic compositions (genetic diversity) Allows for greater survival in a changing environment

Survival Mechanisms Bacteria who need oxygen are called obligate aerobes Bacteria who are killed by oxygen are called obligate anaerobes When conditions become harsh, they can form an endospore that contains DNA. When conditions improve, the endospore germinates. Can take months Bacteria can be harmful to people for these reasons. Bacteria forming on food creates toxins that can harm humans.

Why Bacteria? Bacteria are important in the supporting roles of life. http://www.youtube.com/watch?v=jrSHku6-LFo Bacteria are important in the supporting roles of life. Some are producers that give off oxygen. Some are decomposers that break down nutrients in dead matter and the atmosphere. Some help in nitrogen fixation so plants can turn Nitrogen gas into a useable form. Human Uses for Bacteria Food, Beverages, mining, water treatment, medicine, digestion in the human intestines.

Viruses are non-living particles of nucleic acid, protein and some lipids that cause influenza. Composed of DNA or RNA in a protein coat called a capsid. Viruses that only infect bacteria are called bacteriophages. Named after their disease or discoverer. Likely evolved later since they are dependent on living things. Why Non-Living? Cannot reproduce without infecting a host cell Do not grow and develop Do not respond to the environment. Viruses

Viral “Reproduction” Lysogenic cycle Virus attaches to host cell Inserts viral nucleic acid and inserts it into the host cell’s chromosome (prophage) Gets replicated as host cell divides (through mitosis) Can remain inactive for a long period of time. Like Bacteria, Viruses produce disease by disrupting the body’s normal equilibrium. They either directly attack cells or cause cells to change their patterns of growth or influence their function in the body.

Lytic Cycle Lytic cycle Starts as the lysogenic cycle until triggered. Takes over cell machinery to make virus only! (Chops up cell’s DNA to shut down all defenses.) Viruses are assembled in the host cell Burst out of the host cell releasing new virus 30 min = 200 viruses

HIV virus Retroviruses Use RNA instead of DNA Reverse transcriptase creates DNA from the RNA in the host cell In Sub-Saharan Africa over 23 million living with HIV/AIDS, 4 million infected each year. HIV contact via Saliva/Sexual Contact Mucus Membranes Shared hypodermic needles Blood transfusion (rare)

Tales of HIV and AIDS http://streaming.discoveryeducation.com/search/assetDetail.cfm?guidAssetID=b2c398aa-64e3-4fed-9113-edbba97e7b1f&tabDisplay=myContent

Preventing Disease Vaccine – preparation of weakened or killed pathogens that is injected for the creation of immunity against the pathogen. Control – Sterilization by Heat, Disinfectants, Food Storage (Cans, etc) Antibiotics – Compounds that block the growth and reproduction of bacteria. One of the major reasons the for dramatic increase in life expectancy in the past 200 years. Not effective against viruses.