NOTES: 20.2 (& 20.3)

How are Bacteria Different from Viruses?  Bacteria are different from viruses in that they: -are much bigger -have a different structure (made of cells)  therefore are considered “LIVING” -can reproduce (unlike viruses, which require a host cell)  Bacteria are PROKARYOTES (no nucleus)  Bacteria have 2 Kingdoms: Kingdom Archaebacteria and Eubacteria

Some bacteria you are probably familiar with…

Bacteria…  are unicellular  are prokaryotes  have ribosomes  have genes (typically in a single circular chromosome)  often have a cell wall (protection) **many antibacterial drugs target the cell wall

The Size of Bacteria  Prokaryotes typically range in size from 1-5 μm (micrometers)

The Structure of Bacteria  3 basic shapes: rod-shaped, spherical, spiral  they may form long chains, large clumps / clusters, or colonies  movement: propelled by flagella or cilia

“Breathing” ( RESPIRATION ) in Bacteria  some are aerobic : respiration requires oxygen -obligate aerobes - cannot survive without oxygen EX: Mycobacterium tuberculosis (TB)  some are anaerobic: respiration without oxygen -obligate anaerobes - cannot survive with oxygen EX: Treponema pallidum (syphilis)

How Do Bacteria Obtain Energy?  some make their own food (like plants) = AUTOTROPHS  some obtain their food (like us) = HETEROTROPHS These bacteria eat the nutrients in the agar.

Reproduction in Bacteria  most reproduce through BINARY FISSION (asexual) = offspring are clones

 other bacteria exchange genetic information through CONJUGATION (a.k.a. bacteria “sex”) -a hollow bridge forms between the 2 bacterial cells and genes move from 1 bacterium to the other -ADVANTAGE: increases genetic diversity in the bacterial population

 if food and space are not an issue, bacteria divide at astonishing rates!  some can divide every 20 minutes!!  if this were to continue to happen, the bacteria would reach a mass of 4000x the mass of the Earth in 48 hours!

EXPONENTIAL GROWTH!!!

How Bacteria Can Be Controlled:  STERILIZATION: -heating / boiling OR use a disinfectant (i.e. alcohol, bleach)  FOOD PROCESSING: -boiling, frying, steaming, refrigeration, salt, vinegar

As labeled by humans, there are both “BAD” bacteria and “GOOD” bacteria.

 Bacteria that cause illness and disease (PATHOGENIC)  Bacterial diseases: -diptheria, tuberculosis, typhoid fever, tetanus, syphilis, cholera, bubonic plague  How are the diseases caused? -bacteria damage the cells & tissues of an organism directly by breaking down the tissues for food -OR…bacteria release toxins (poisons) that travel through the organism’s body

WARNING: Disturbing Picture!!

Flesh-eating bacteria Ocean warning!

Diseases caused by bacteria: DiseaseTransmissionSymptomsTreatment TuberculosisInhaleFatigue, cough, fever, chest pain antibiotics TetanusPuncture wound Stiff jaw, muscle spasms, paralysis Clean wound, antibiotics, antitoxin Strep throatInhale or ingest through mouth Fever, sore throat, swollen gland Antibiotic Lyme diseaseBite of infected tick Rash at site of bite, chills, aches Antibiotic CholeraContaminated water Diarrhea, vomiting, dehydration Antibiotics, replace fluids

 Since 1900, the life expectancy in the U.S. has increased from 47 years to 75 years…WHY???  better public health  improved water / sewage treatment  nutrition, medical care  ANTIBIOTICS

bacteria that humans use and need in their everyday lives. Escherichia coli (Esh-er-ish-e- ah coal-eye): one of many kinds of microbes that live in your gut. Wanted for helping you digest your food every day.

Saccharomyces cerevisiae (sack-arrow- my-seas sair-uh-vis-ee- ay): a.k.a. baker's yeast. Wanted for making bread rise. Pseudomonas putida (sue-doe-moan-us poo- tea-dah): one of many microbes wanted for cleaning wastes from sewage water at water treatment plants. Lactobacillus acidophilus (lack- toe-bah-sill-us acid-off-ill-us): one of the bacteria gang wanted for turning milk into yogurt.

Arbuscular mycorrhizas (ar-bus- que-ler my-kuh-rye- zuh): one of a soil- living fungus family. Wanted for helping crops take up nutrients from the soil. Streptomyces (strep-toe-my- seas): soil bacteria wanted for making streptomycin, an antibiotic used to treat infections. Bacillus thuringiensis (bah- sill-us ther-in-gee-in-sis): a.k.a "Bt", a common soil bacterium. Wanted as a natural pest-killer in gardens and on crops.

Good Bacteria in Summary: 1) Nitrogen Fixation  most organisms need nitrogen for DNA, RNA, proteins, and ATP  few organisms can convert nitrogen gas into useable nitrogen so they need the help of bacteria that live in the roots of legumes (beans, peas, etc…)

Good Bacteria in Summary: 2) Recycling of Nutrients  decomposing bacteria break down dead organisms and wastes, returning nutrients to the environment

Good Bacteria in Summary: 3) Foods and Medicines  EX: Swiss cheese, pickles, yogurt  EX: antibiotics that destroy other types of bacteria (streptomycin, erythromycin, etc.) Antibiotics

How Do You Treat a Bacterial Infection?  if prevention fails, take ANTIBIOTICS  antibiotics kill bacteria without harming the cells of humans or animals -they interfere with the cellular processes of bacteria (e.g. stop cell wall synthesis)  many antibiotics are produced naturally by living organisms -ex: penicillin  others are synthetic (man-made)