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
are unicellular are prokaryotes have ribosomes Bacteria 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!!
Ocean warning! Flesh-eating bacteria
Diseases caused by bacteria: Disease Transmission Symptoms Treatment Tuberculosis Inhale Fatigue, cough, fever, chest pain Tetanus Strep throat Lyme disease Cholera Puncture wound Inhale or ingest through mouth Bite of infected tick Contaminated water Stiff jaw, muscle spasms, paralysis Fever, sore throat, swollen gland Rash at site of bite, chills, aches Diarrhea, vomiting, dehydration antibiotics Clean wound, antibiotics, antitoxin Antibiotic Antibiotic 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-eah coal-eye): one of many kinds of microbes that live in your gut. Wanted for helping you digest your food every day.
Lactobacillus acidophilus (lacktoe-bah-sill-us acid-off-ill-us): one of the bacteria gang wanted for turning milk into yogurt. Saccharomyces cerevisiae (sack-arrowmy-seas sair-uh-vis-eeay): a.k.a. baker's yeast. Wanted for making bread rise. Pseudomonas putida (sue-doe-moan-us pootea-dah): one of many microbes wanted for cleaning wastes from sewage water at water treatment plants.
Streptomyces (strep-toe-myseas): soil bacteria wanted for making streptomycin, an antibiotic used to treat infections. Arbuscular mycorrhizas (ar-busque-ler my-kuh-ryezuh): one of a soilliving fungus family. Wanted for helping crops take up nutrients from the soil. Bacillus thuringiensis (bahsill-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)