Bacteria are all the organisms in the kingdoms Archaebacteria and Eubacteria. Bacteria outnumber all the members of all the other kingdoms combined.

Bacteria are all the organisms in the kingdoms Archaebacteria and Eubacteria. Bacteria outnumber all the members of all the other kingdoms combined.

Bacteria Facts: A bacteria cell on average is 1000x smaller then most human cells. They are found in almost all places and environments. They are all Prokaryotic. Only a small number of bacteria bring disease, the rest are vitally important to life and the environment.

Kingdom Archaebacteria: (Archae- from the Greek word for ancient) Considered to be the oldest life forms on earth. They are different from all other bacteria in that, there is no peptidoglycan in their cell walls. They are classified based on the environment they live in: Thermoacidophiles (heat and acid lovers): live in acidic soil, hydrothermal vents, and hot springs. Methanogen (methane-producer): Live in anaerobic environments such as swamps and sewage. They use anaerobic respiration and release methane as waste. Halophiles (salt lovers): Live in areas with extremely high concentrations of salt, such as the Dead Sea and Salt Lake City.

Kingdom Eubacteria: Largest bacteria kingdom and represent the most common bacteria. They vary in morphology and environment and are very difficult to classify. (there is much debate as to how many phyla it contains). They are classified based on their shape. The rest of the notes will deal only with Eubacteria unless otherwise stated.

Bacteria Shapes: Coccus: A spherical or oval bacteria. Bacillus: A rod-shaped bacteria Spirillum: A spiral or cork-shaped bacteria These shapes are often used in the scientific names of bacteria, for example Streptococcus, Lactobacillus, and Rhodospirillum.

Structure of Bacterial Cell:

Cell Wall: Contains peptidoglycans for strength and shape. Capsule: Also called slime layer and can be very thick to very thin. It protects the cell from invaders and drying out. Cytoplasm: DNA forms a single double stranded circular chromosome. There may also be small circular pieces of DNA called plasmids.

Movement: Many bacteria have flagella, a long thread-like structure that allow bacteria to direct their movements.

Bacterial Reproduction: Bacteria undergo asexual reproduction by binary fission (splitting in half). Although bacteria reproduce asexually, they can transfer genetic information using conjugation or transformation. Conjugation: A conjugation tube called a pilus connects from one bacteria to another and plasmids (circular pieces of DNA)are transferred. Transformation: Bacteria pick up plasmids free floating in the environment.

Bacterial Nutrition: Bacteria have a wide range of methods for obtaining energy. Autotrophic Bacteria: Many bacteria can use photosynthesis or chemosynthesis (Making sugar from carbon dioxide and water using simple inorganic compounds) to produce food Heterotrophic Bacteria: Many are symbiotic (live inside a living host) or decomposers (eat dead organisms).

Viruses were discovered in the 1930s by Wendell Stanley, who isolated the tobacco mosaic virus. He found that tobacco leaves could get the disease from even a small amount of virus and that over time, the number of viruses increases. This indicated that it might be living as opposed to a disease caused by a chemical. Thus the virus was discovered.

Structure of a Virus: A virus consists of 2 basic parts: A core and capsid. Core: Consists of genetic material (either DNA or RNA) Capsid: Protein covering. Sometimes found with plasma membrane with marker proteins.

Is a Virus alive? No, Viruses violate the rules of life in the following ways: A virus cannot survive outside a host A virus has no cells or cellular structures Viruses do not move or respond to stimulus independently How do you classify Viruses? Since viruses are not alive, they are not included in Linnaeus's taxonomic system. They are grouped independently by their nucleic acids: RNA or DNA. A virus with RNA is called a Retrovirus. These two groups are similar but act differently within the cell.

Life Cycle of a Virus There are 2 cycles a virus may carry out within the cell depending on environmental conditions: The Lytic Cycle or Lysogenic Cycle Lytic Cycle: (used under optimal conditions) 1. The virus attaches to bacteria (host) 2. The virus inserts its DNA into the bacteria 3. The viral DNA/RNA directs the cell to produce more viruses. 4. The virus self-assembles in large numbers till the cell bursts. 5. Each virus can then go on to infect another cell.

Lysogenic Cycle: (used under harsh conditions) 1. The virus binds to bacteria (host) 2. The virus inserts its DNA into the bacteria 3. The viral DNA gets incorporated into the cell's chromosome 4. Viral DNA is replicated along with chromosomal material, ready to begin the lytic cycle when conditions improve.

Viral Diseases: Viruses are highly specific regarding their host cells. They are specific to species and even type of cell within the body. For example, small pox and the mumps are specific to human skin cells. However, they may change over time and spread between species (for example, most flu viruses originate from birds). These viruses are called emerging viruses and are difficult to control and treat. This is the main reason for a new flu vaccination every year.

Bacterial vs. Viral Infections Viral infections typically occur in the respiratory system and usually have a low fever, body aches, red sore throat (w/ no white spots), runny nose with clear/white mucus. Sometimes have Unproductive Cough as well. Bacterial infections typically have the similar symptoms as viral but have a higher fever, body chills & sweating (from fever), sore throat with white spots, and green mucus. May have Productive Cough as well. IMPORTANT NOTE: It is possible to have both a bacterial & viral infection at the same time and if the sickness is severe and/or lasts more than 7 days please see your primary care physician asap!!

Treatment of Viral Conditions: Vaccination: a preparation of killed viruses, weakened viruses, or living viruses administered to produce or artificially increase immunity to a particular disease. It does this by triggering the body to make antibodies against the disease which are then stored for any future contact.

Antiviral Drugs: Once someone has a viral infection, we can no longer vaccinate. There are drugs that can help control the infection. These drugs help by inhibiting viral action within the body. Retroviral Drugs: Designed to stop viral RNA from being transcribed inside the cell. These are used globally to help treat the symptoms of HIV. Protease Inhibitors: Designed to stop the production of capsids within a cell. If a virus has no protein coat, it cannot infect another cell.

Treatment of Bacterial Infections: Antibiotics: a substance produced by or a semisynthetic substance derived from a microorganism (usually mold) and able in dilute solution to inhibit or kill a bacteria. Kills all bacteria in a patient s body not just the bad bacteria!!

Pathogen: An agent that invades the body and causes a disease. Bacteria and viruses are common pathogens. Pathogens cause disease within the body by: Tissue Destruction: Pathogens obtain their nutrition from host tissue (bacteria) or use host cells for reproduction (virus) causing tissue to be destroyed. Toxin Formation: Many pathogens (especially bacteria) have the ability to produce toxins which cause destruction to host s body.

How Diseases are spread? Airborne Infection: Pathogens are carried in water droplets in the air. Many respiratory diseases are spread this way. Direct Contact: Pathogens can spread by direct contact with a person, either their bodily fluids or just touch. The common cold, flu, measles, and STDs are spread this way. Wound Infection: Pathogens can enter the body through open wounds. Many bacterial infections like Staphylococcus, Tetanus, and Gangrene spread this way. Vector-Carried Infection: Pathogens can be carried by insects called vectors. Malaria from mosquitos and the Bubonic Plague spread this way. Immune Carriers: People and some animals can carry and spread a disease without having symptoms of the disease. Hepatitis and Polio can be spread this way.

Defense Against Disease: 1 st Line of Defense: Structural Defense (to keep pathogens from entering the body) Skin: Forms a barrier against invaders. It also releases fatty acids and salts to inhibit pathogens. Mucous Membranes: Forms a barrier against pathogens in the digestive, urinary, and respiratory tracts. They form a wall of tightly packed cells with cilia that secrete mucous. This mucous traps pathogens and other foreign materials that can then be swept away.

Internal Microorganisms: There are many micro-organisms that live within our body protecting us from harmful pathogens. If a person continues antibiotics for too long, these helpful flora/fauna can be killed off and the person will be susceptible to disease.

2 nd Line of Defense: The Lymphatic System and Immunity The Lymphatic System: part of the circulatory system, comprising a network of conduits called lymphatic vessels that carry a clear fluid called lymph. This lymph is essentially recycled blood plasma without the red blood cells The lymph fluid is carried through lymph nodes and then rejoins the blood stream near the neck. This system is responsible for most of our immune responses.

Lymph Nodes: Small masses of tissue along the lymphatic vessels. As the Lymph fluid flows in and out, invaders like Bacteria and Viruses are recognized and destroyed. There are 2 main types of cells found in the Lymph Nodes: Lymphocytes and Macrophages. Lymphocytes: White blood cells. They may become either T-cells or B-cells that assist immunity in separate ways (discussed in the next section) Macrophages: Large phagocytic cells. They ingest any foreign substances/pathogens found in body. When there are many pathogen-macrophage battles, the lymph nodes swell.

Immunity: when a body reacts to a disease and destroys it or renders it harmless. Antigen: any foreign substance to which the body responds. There are 2 basic processes of immunity in the human body: Cell-mediated Immunity and Antibody-Mediated (Humoral) Immunity.

Cell-Mediated Immunity: Immunity assisted by T-Cells. When a macrophage ingests an antigen, it forms a antigen-macrophage complex. A helper T-cell matches and binds to the complex. These helper T-cells then start to divide rapidly and some become the other T-cells. Helper T-Cells: after dividing rapidly they begin to fight the infection.

Killer T-cells: Killer T-cells attack body cells affected by the antigen. It releases a protein that causes the cell to burst and die. They will continue to fight until called off by suppressor T-cells. Suppressor T-cells: Towards the end of the fight, suppressor T-cells stop the activities of helper T-cells and killer T-cells, returning them to normal operations. Memory T-cells: These cells will circulate for years, ready to recognize and attack if the same antigen were to reappear.

Antibody Mediated Immunity (Humoral Immunity): Immunity assisted by B-cells. Uses activated B-cells to make Antibodies. Antibodies are free proteins that float around the blood or lymph fluid. B-cells are activated by helper T-cells. They then become either plasma cells or memory B-cells. The plasma cells begin to make large amounts of Antibodies, specific to the antigen. Memory B- cells live for several dozen years and remain ready to respond to any future infection of the same antigen.

Antibodies react to the antigen in many ways. They may be toxic to the antigen or just prevent them from attacking a cell, but all of them stop the destructive activity of the antigen. It may take a while to build up the proper amount of specific antibodies, which is why you may be sick for days before feeling better. However, if you are attacked by the same antigen again, the memory cells will quickly act and you may not even feel sick.

Autoimmune Diseases: Disease in which an individual s immune system cannot distinguish body cells from invaders. The immune system makes auto-antibodies (self-attacking antibodies) and killer T-cells to attack the body. Researchers are unsure why this happens, but it is degenerative. One example is Multiple Sclerosis (MS), where the immune system attacks the myelin sheath on nerve cells. This causes severe nerve damage, leading to physical and mental degradation.