Prokaryotes, Eukaryotes, & Protists

Antibiotic Action

(want to kill bacteria without killing host) -prevent bacteria from making cell wall -prevent small bacterial ribosomes that make proteins needed for bacteria to live

Beneficial Bacteria

-Gut Flora: allow proper digestion of food and protect your bowels from pathogenic bacteria

Protists

-a group of mostly unicellular eukaryotic organisms that are not fungi, plants, or animals -not a valid evolutionary group -most eukaryotes are protists and most protist are unicellular

Endospores (prokaryotes)

-can withstand extremely harsh conditions and formed by bacteria when environmental pressures threaten death -copy of chromosomes surrounded by tough, multilayered structure -endospore is desiccated and all metabolic processes cease -can survive for centuries and resume regular processes as soon as environment is favorable

Enteric Nervous System

-component of mammalian nervous system that enervates your gastrointestinal tract -gut bacteria can secrete neuroendocrine hormones that influence enteric nervous system -hormone secretion varies depending on composition of gut flora -gut flora composition varies based on the environment you provide -bacteria alter you for their benefit (secrete hormones that result in specific craving depending on what they prefer)

Flagella (prokaryotes)

-long, whip-like appendages that allow directed movement -allows taxis (movement directed toward a stimulus)

Cell Walls (prokaryotes)

-maintains cell shape, provides protection, limits water lost -made of peptidoglycan (rather than chitin or cellulose as in eukaryotes) -can distinguish gram-positive (thick) and gram-negative (thin) species

Green Algae

-photosynthetic protists -paraphyletic group (doesn't include land plants) -closest relative to land plants -Features 1) often live in intertidal zones 2) zygotes coated with sporopollenin (tough polymer that prevents desiccation) 3) flagellated gametes (gametes swim through water) 4) no internal structural support (supported by water)

Brown Algae

-protists -large, multicellular photosynthetic algae -contain carotenoids (orange-ish brown photosynthetic pigment -Holdfast: anchors to seafloor -Blade: leaf-like structures increase photosynthetic surface areas -Stipe: Stalk-like structure brings blade closer to ocean surface and therefore light -very similar to plants, but DNA analysis indicates they arose from entirely different evolutionary lineages (convergent evolution)

Archaea

-single celled prokaryotes -often extremophiles -Extreme thermophiles (thrive in heat) -Extreme halophiles (salty conditions) -more closely related to eukarya

Plasmid

-small, independently replicating, circular DNA -often carry alleles for antibiotic resistance

Genetic Information of Prokaryotes

-smaller genomes -chromosomes are circular -contain plasmids -gene translation to proteins is similar, but with much smaller ribosomes -reproduce by binary fission: splitting one cell into two after replication of genetic information

Nitrogen Fixation

-some prokaryotes can convert atmospheric N2 to ammonia NH3 -plants can't use N2 to grow and can't fix nitrogen, therefore they rely on bacteria for nitrogen fixation

Capsules (prokaryotes)

-sticky layer of polysaccharide or protein -allows adhesion to surfaces and often inhibits action of antibiotics

Mitochondria and Chloroplasts

1) Both have their own lipid bilayers 2) Both have circular DNA that can replicate independently 3) Both have their own ribosomes that are smaller 4) Both reproduce by a splitting process similar to fission -share many similar characteristics with prokaryotes

Challenges to moving to land

1) must be able to avoid desiccation 2) must develop supportive tissue to remain upright (and compete for sunlight) 3) need to have gametes that don't require water to fertilize

Conjugation

DNA transferred between 2 prokaryotic cells through a pilus

Pathogenic Bacteria

bacteria associated with disease

Transformation

bacteria take up DNA from closely related organisms and incorporate it into their genome

Transduction

bacteriophages (viruses that infect bacteria) carry DNA from one bacteria host to another

Endosymbiont Theory

mitochondria and chloroplasts derived from ancestral prokaryotes that were engulfed by another cell and the relationship became symbiotic

Eukaryotes

organisms with cells that have membrane-bound organelles and a membrane-bound nucleus -domain: eukarya -includes protist, plants, fungi, and animals

Prokaryotes

organisms with cells that lack membrane-bound organelles and a membrane-bound nucleus -two domains: Bacteria and Archaea