I. Prokaryotes
A. Prokaryotes are diverse and widespread - Despite their small size, prokaryotes have an immense impact on our world - More prokaryotes inhabit a handful of soil than the amount of humans that have ever lived - Bacteria, a type of prokaryote, cause half of all human illnesses, including: plague and cholera, strep throat, ear infections, and STD’s -Pathogens – are bacteria that are disease causing

B. Bacteria and Archaea - Prokaryotes lack a nucleus and other membrane enclosed organelles - There are now two types of Prokaryotes, Bacteria and Archaea, after they realized bacteria are closer to eukaryotes than Archaea - Differences between the two show up in their cell walls and membranes. -Peptidoglycan – Found in the cell wall of bacteria but not in Archaea

C. Prokaryotes come in a variety of shapes - Cocci – spherical prokaryotic cells that occur in chains such as streptococci that causes strep throat - Bacilli – Rod shaped prokaryotes usually occur singly but sometimes paired - Some prokaryotes are curved known as vibrios and others are helical known as spirilla or spirchetes

D. Various structural features - External structures are vital, including their cell wall that maintains its shape and provides protection - Gram strain- a way to classify bacteria by comparing the thickness of the l layer of Peptidoglycan. Bacteria can be Gram-positive or negative - Gram strain is valuable in medicine as gram-negative bacteria are more dangerous because their membrane resists antibiotics - Pili – Some prokaryotes use these paired appendages to stick to surfaces - Some prokaryotes have a flagella which allows them to swim faster - Endospore- has a thick coat allowing it to withstand harsh conditions E. Prokaryotes obtain nourishment in a variety of ways - Prokaryotes can be either phototrophs (receive energy from light) or chemotrophs (receive energy from stored in organic or chemical compounds - Autotrophs – organisms that make their own organic compounds from inorganic sources -Heterotrphs – Most prokaryotes, animals, and fungi that obtain their carbon atoms from other organic compounds - Photoautotrophs – such as Cyanobacteria that use sunlight for energy -Photoheterotrophs - obtain energy from the sun but get their carbon from other organic sources - Chemoautotroph- gets their energy from inorganic chemicals and use carbon to make organic molecules while chemeoheterotrophs acquire energy and carbon from organic molecules. -Some live in biofilms – meaning they live in surface-coating colonies

F. Archaea thrive in extremes - Extreme Halophiles- “salt lovers” are Archaea that thrive in salty places such as the Great Salt Lake and the Dead Sea. - Those that love hot water are known as extreme thermophiles. They live in deep sea vents and in water up to 100° C - Methanogens – live in anaerobic environments and give off methane as a waste product. They can be found in the digestive tracks in animals. - However, Archaea don’t just live in extreme environments but in moderate ones too making them the most abundant cell types on earth.

G. Bacteria included a diverse assemblage of prokaryotes - Bacteria is divided into 9 groups, five are proteobacteria which are subgroups of a gram negative bacteria - Gamma proteobacteria live in animal intestines such as salmonella, vibrios cholerae, and E. coli - Chlamydias – live inside eukaryotic host cells and is a common cause of blindness and the most common STD. -Spirochetes – are helical bacteria that spiral through their environment and are notorious pathogens that cause syphilis and Lyme disease - Gram-positive bacteria – rivals the proteobacteria and create large chains commonly found in the soil. Streptococcus is gram positive - Cyanobacteria – the only prokaryotes that have oxygen-generating