Bell-Ringer What is a virus? What are the characteristics of life? Is a virus living? Explain the structure of a virus. SPRING BREAK

Classification of Living Things Taxonomy Classification of Living Things

Three domains Archaea Eubacteria Eukarya “ancient” Unicellular Prokaryotic (but not bacteria) Found in most extreme environments Eubacteria Prokaryotic Found in all parts of the world Eukarya Unicellular or Multicellular Eukaryotic

Six kingdoms Domain Archaea Domain Eubacteria Domain Eukarya Kingdom Archaea Domain Eubacteria Kingdom Eubacteria Domain Eukarya Kingdom Plantae Kingdom Protista Kingdom Fungi Kingdom Animalia

Kingdom Archaea Extreme environment Anaerobic Photo/chemosynthetic Heterotrophic

Kingdom Bacteria Unicellular Prokaryotes Photo/chemosynthetic or heterotrophic

Cell structure

What are bacteria? Unicellular Circular DNA No organelles E. Coli O157:H7 can make you very sick. Earth’s oldest life forms – between 3.5 and 3.8 billion years old Most abundant life form – up to 2.5 billion individual bacteria in 1 gram of fertile soil Very adaptable – found in all of Earth’s ecosystems Can be found on most materials and surfaces Billions on and in your body right now Unicellular Circular DNA No organelles Streptococcus can cause strep throat. This E. coli helps you digest food.

Shape

Bacterial Shapes 3 main shapes - coccus – sphere - bacillus – rods - spirillum - spiral

Cocci Bacilli Spirilia Cluster of cocci

Bacterial Structure: Cell Wall Made of peptidoglycan – a combination of protein and polysaccharides Some bacteria called Gram negative bacteria have an additional layer of membrane that contains lipopolysaccharide - this extra layer inhibits the uptake of antibiotics – protecting the bacteria cell wall cell membrane cell membrane lipopolysaccharide cell wall Outer membrane

Gram + vs. Gram - The type of cell wall is used by doctors to help diagnose disease The bacteria are stained with a special stain called Gram stain Absorb stain appear purple Bacteria without the extra membrane, appear purple. These are Gram positive (Gram +) bacteria Named after Danish Scientist Hans Christian Gram – No Joke Gram was working on Pneumonia and discovered that different organisms took up stain differently. The process stains the both types of cells with crystal violet, and then they are treated with alcohol which Bacteria with the extra membrane appear pink. These are Gram negative ( Gram -) bacteria Don’t absorb stain appear pink 13

Bacterial Characteristics Metabolic diversity – Bacteria can produce energy in a variety of circumstance Autotroph – (self-feeding) – some bacteria produce their own food some use photosynthesis – get energy from light some use chemosynthesis – get energy from chemicals Heterotroph - (other feeding) – many bacteria are unable to produce their own food and are required to eat other things 14

Reproduction Binary fission (Asexual) Conjugation Spore Formation Other: Transformation Transduction

Exchanging Genetic Information

Reproduction - Binary Fission Bacterial cells undergoing binary fission 17

Cellular organism copies it’s genetic information then splits into two identical daughter cells

Conjugation- one cell passes a copy of its plasmid or chromosome to another Recipient Cell Donor Cell A special pilus forms a connection called a conjugation bridge between 2 bacterial cells Plasmid Conjugation bridge The donor cell copies its plasmid or chromosome and passes the copy through the conjugation bridge Cells separate 19

Two organism swap genetic information such as how to be resistant to penicillin.

Spore Formation: Endospore A type of dormant cell Exhibit no signs of life Highly resistant to environmental stresses such as: -High temperatures -Irradiation -Strong acids -Disinfectants

Transformation: Bacteria absorb “naked” DNA from the environment 22

Transduction – DNA is carried from one bacteria to another by a virus 23

Uses/benefits Today You come up with some! Think of important tasks performed by bacteria that we’ve already studied! Look it up!

Bacteria Play Important Roles in Ecosystems Decomposers – recycle dead organisms releasing their nutrients back to the environment for use by other organisms. Without decomposers, the elements on earth would have remained locked up in dead organisms and life would have ceased.

Bacterial Roles: Nitrogen Fixation some bacteria contain enzymes which allow them to convert (or fix) nitrogen from the air into a useable form - they are nitrogen fixing bacteria - Why do living things use nitrogen?

Bacterial Roles: Producers In some ecosystems chemosynthetic and photosynthetic bacteria serve as the basis of the food chain

Bacterial Roles: Symbiotic Bacteria Many bacteria live in or on other organisms (including humans) and aid their host - some live in the gut of herbivores helping to digest cellulose - bacteria in the gut of humans aid digestion and produce vitamins - bacteria on skin and in body openings help prevent infection by harmful organisms Stomach bacteria help maintain stomach pH, produce B and K vitamins, studies show that babies given lactobacilius bacteria have less diarrhea

Bacterial Roles: Pathogenic Bacteria Pathogens are agents that cause disease - only a small portion of bacteria are pathogens - most bacteria diseases are caused by toxins released by the bacteria - these toxins: - poison cells and damage tissue - interfere with cell signaling - over-stimulate cells causing them to malfunction

Are all bacteria pathogens? No, most are harmless Some are even helpful Examples of helpful bacteria: Lactobacillus: makes cheese, yogurt, & buttermilk and produces vitamins in your intestine Leuconostoc: makes pickles & sauerkraut Pediococcus: makes pepperoni, salami, & summer sausage

A Closer Look – Helpful Bacteria www.bioweb.usu.edu Pediococcus - used in production of fermented meats Lactobacillus casei – found in human intestines and mouth to improve digestion Leuconostoc cremoris – used in the production of buttermilk and sour cream Lactobacillus bulgaricus – used in the production of yogurt

What are some common pathogens? E. coli O157:H7 Pathogenic E. coli (like O157:H7) Found in ground beef, contaminated fruits and vegetables Salmonella Found in raw meats, poultry, eggs, sprouts, fruit and vegetables Listeria Found in deli foods, lunch meats, smoked fish and vegetables Salmonella Listeria

What shape are these bacteria? Cocci, bacilli, or spiral? Examples of Pathogens Salmonella E. coli O157:H7 What shape are these bacteria? Cocci, bacilli, or spiral? Staphylococcus aureus Campylobacter jejuni

Antibiotics Antibiotics are chemicals which either kill bacteria or prevent their growth and reproduction Bacteria and other microbes produce antibiotics to reduce competition from other organisms Penicillin was the first to be use to fight disease - discovered accidently by Alexander Fleming in 1928 The discovery of antibiotics revolutionized the treatment of disease Antibiotics which kill bacteria are bacteriacidal, the antibiotics which stop growth are referred to as bacteriastatic

Antibiotic Action Antibiotics effect bacteria, but not eukaryotic cells Antibiotics attack bacteria in 5 ways - some damage the cell walls or prevent new cell wall from forming - some damage the cell membrane - some prevent protein synthesis - some prevent DNA from being copied - some interfere with bacterial metabolism Bacterial ribosomes are 70S 50S and 30S subunits – antibiotics impact these subunits Eukaryotic ribosomes are 80S 60S and 40S subunits – antibiotics don’t impact these

Antibiotic Resistance Some bacteria have developed a resistance to the effect of some antibiotics The number of resistant bacteria is growing. The problem is increased by overuse and misuse of antibiotics. - from the use of antibiotics to treat viral infections – Antibiotics don’t effect viruses. - from the use of antibiotics in livestock (cattle, chickens, pigs) –Antibiotics show up in the meat and milk. - Or, people take the antibiotics until they feel better, but stop before all of the bacteria are destroyed. This kills the most susceptible bacteria, but leaves the more resistant bacteria

Syphilis--Treponema pallidum/Bacterial Causes an ulcer at the site of infection. 4 stages of life. Treatment now with Penicillin. 37

Mycobacterium leprae/Bacteria Rod like Bacteria-spread through coughing and sneezing. In old days they thought it was genetic and they isolated people-Leprae colonies. Now (1940)there is antibiotic treatment to clear up the symptoms in 6-12 months. 38