Bacteria

Bacteria Earth’s oldest life forms 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 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 Very adaptable – found in all of Earth’s ecosystems ecosystems

Bacteria Characteristics Unicellular Unicellular Circular DNA Circular DNA No organelles No organelles 1/10 th the size of eukaryotic cells 1/10 th the size of eukaryotic cells Flagella-long hair-like structure used for movement Flagella-long hair-like structure used for movement Reproduce asexually –Binary Fission Reproduce asexually –Binary Fission

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

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

Bacterial Structure Cell Wall Cell Membrane Pilus chromosome plasmid flagellum nucleoid ribosome cytoplasm capsule

Gram + vs. Gram - Absorb stain appear purple Don’t absorb stain appear pink The type of cell wall is used by doctors to help diagnose disease The bacteria are stained with a special stain called Gram stain Bacteria without the extra membrane, appear purple. These are Gram positive (Gram +) bacteria Bacteria with the extra membrane appear pink. These are Gram negative ( Gram -) bacteria

Bacterial Structure continued Pili – hairlike structures usually found Pili – hairlike structures usually found in Gram neg. bacteria. Help the bacteria stick to surfaces. in Gram neg. bacteria. Help the bacteria stick to surfaces. Also forms conjugation bridge Chromosome – a single loop of DNA Chromosome – a single loop of DNA that is folded on itself that is folded on itself - controls the cell’s function - controls the cell’s function Nucleoid – the region of the cytoplasm Nucleoid – the region of the cytoplasm where the DNA is found where the DNA is found Plasmid – an accessory loop of DNA – small contains only a few genes - can be responsible for: conjugation, antibiotic resistance, unique metabolic properties – like the ability to use hydrocarbons Plasmid – an accessory loop of DNA – small contains only a few genes - can be responsible for: conjugation, antibiotic resistance, unique metabolic properties – like the ability to use hydrocarbons Capsule – found outside some bacteria stores nutrients and protects the bacteria from changing environmental conditions Capsule – found outside some bacteria stores nutrients and protects the bacteria from changing environmental conditions

Reproduction - Binary Fission Bacterial cells undergoing binary fission Bacterial cells undergoing binary fission

Reproduction - Binary Fission Asexual reproduction Asexual reproduction - offspring are genetically - offspring are genetically identical to parent – no identical to parent – no new genetic combinations new genetic combinations - under ideal conditions - under ideal conditions can occur every 20 min can occur every 20 min - creates large numbers - creates large numbers of bacteria in a short of bacteria in a short time time

Each spot represents Each spot represents a single bacterial a single bacterial cell that reproduced cell that reproduced by binary fission to by binary fission to produce millions of produce millions of genetically identical genetically identical cells. cells. Genetically identical, Genetically identical, good or bad? good or bad?

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

Bacteria Play Important Roles in Ecosystems Decomposers Decomposers – recycle dead organisms releasing their nutrients back to the environment for use by other organisms – SPONCH – recycle dead organisms releasing their nutrients back to the environment for use by other organisms – SPONCH Without decomposers, Without decomposers, the elements on earth the elements on earth would have remained would have remained locked up in dead organisms and life would have ceased 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 some bacteria contain enzymes which allow them to convert (or fix) nitrogen from the air into a useable form - they are nitrogen fixing bacteria - they are nitrogen fixing bacteria - Why do living things use nitrogen?

Bacterial Roles: Producers In some ecosystems In some ecosystems chemosynthetic and chemosynthetic and photosynthetic bacteria photosynthetic bacteria serve as the basis of serve as the basis of the food chain the food chain – chemosynthetic bacteria in deep ocean vents convert hydrogen sulfide (H 2 S) gas into energy - cyanobacteria are photosynthetic bacteria - cyanobacteria are photosynthetic bacteria which act as producers in many aquatic which act as producers in many aquatic ecosystems ecosystems

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 - some live in the gut of herbivores helping to digest cellulose - bacteria in the gut of humans - bacteria in the gut of humans aid digestion and produce vitamins - bacteria on skin and in body - bacteria on skin and in body openings help prevent infection by harmful organisms

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

Pathogenic Bacteria: Biofilms Some bacteria can form a biofilm – a matrix made of polysaccharide Some bacteria can form a biofilm – a matrix made of polysaccharide - once formed, the matrix traps other bacteria - once formed, the matrix traps other bacteria - the biofilm protects the bacteria, making it hard to kill them - the biofilm protects the bacteria, making it hard to kill them

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

Antibiotic Action Antibiotics effect bacteria, but not eukaryotic cells Antibiotics effect bacteria, but not eukaryotic cells Antibiotics attack bacteria in 5 ways Antibiotics attack bacteria in 5 ways - some damage the cell walls or prevent new cell wall from forming - some damage the cell membrane - some damage the cell membrane - some prevent protein synthesis - some prevent protein synthesis - some prevent DNA from being copied - some prevent DNA from being copied - some interfere with bacterial metabolism - some interfere with bacterial metabolism

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

Black Plague-Yersinia pestis

Syphilis--Treponema pallidum/Bacterial

Mycobacterium leprae/Bacteria

Clostridium perfringes/Bacteria

Vocabulary autotroph pili heterotroph nucleoid peptidoglycan capsule plasmid conjugation bridge Gram -obligate aerobe Gram +obligate anaerobe binary fissionfacultative anaerobe conjugationnitrogen fixing bacteria transductioncyanobacteria transformationpathogens biofilm