Bacteria

Spirillum (spiral shape) What are Prokaryotes? Prokaryotes are single-celled organisms that do not have membrane-bound organelles They have adapted to live in almost every environment They are generally found in three shapes Baccilus (rod shaped) Coccus (sphere shape) Spirillum (spiral shape)

Kingdoms of Prokaryotes Archaea Found in extreme environments Structurally different from bacteria Bacteria Most prokaryotes are in this group Can be found virtually anywhere!

Bacterial Structure Bacteria have genetic material in the form of a single loop of DNA that is clustered in a mass called a nucleoid Bacteria also have ribosomes and many enzymes Bacteria have cell membranes and cell walls made of peptidoglycan Gram positive bacteria have a thick layer of peptidoglycan Gram negative bacteria have a thin layer of peptidoglycan

Bacterial Structure Bacteria move by rotating their flagella Bacteria stick to surfaces with pili

Obtaining Energy & Nutrients Bacteria differ in how they obtain energy and nutrients Photoautotrophs get their energy from sunlight Cyanobacteria were responsible for most of the oxygen on earth Chemoautotrophs can get their energy from inorganic sources Heterotrophs get their energy from other organisms (alive or dead)

Reproduction and Adaptation Bacteria reproduce through binary fission When a single cell divides into two identical new cells

Reproduction and Adaptation Bacteria can exchange genetic material through conjugation During conjugation, a pilus from one bacterium attaches to a second bacterium The cells then join and exchange genetic material Benefit: Creates genetic diversity which increases the chance of survival in a changing environment

Reproduction and Adaptation Some bacteria survive harsh conditions by forming thick-walled structures called endospores They form inside bacteria They surround the DNA and protect it from harsh conditions When harsh conditions end, endospore can disassemble and bacteria can thrive

Bacteria & Humans Pathogenic (disease-causing) bacteria are responsible for diseases such as Strep Throat and Pneumonia One can take antibiotics to cure a bacterial infection Antibiotics interfere with the peptidoglycan cell wall of bacteria It is important to take antibiotics as prescribed to avoid antibiotic resistance