Microbiology

Prokaryotes * flagella:: bacteria use to propel themselves * pili:: allow prokaryotes to stick to substrates or exchange DNA
Bacteria * no membrane bound organelles, no nuclear envelope, circular chromosome * ^^peptidoglycan in cell wall^^, one kind of RNA polymerase, inhibited by antibiotics, can’t survive in extreme temperatures * antibiotics:: many target peptidoglycan and damage bacterial cell walls * gram stain:: used to classify bacteria into gram-positive and gram-negative groups based on cell wall composition
Archaea * no membrane bound organelles, no nuclear envelope, circular chromosome * ^^polysaccharides and proteins in cell wall^^, many kinds of RNA polymerase, not inhibited by antibiotics, can survive in extreme temperatures
bacterial photosynthesis:: bacteria have modified cell membranes that allow them to perform photosynthesis or respiration, unlike plants who use membrane bound organelles such as the chloroplast * endosymbiotic theory - this evolved when cells engulfed photosynthetic/aerobic bacteria

bacterial genetic material:: chromosomes are a singular circular piece of DNA, extra DNA is stored in plasmids, small ribosomes
horizontal transfer:: the exchange of genetic information between bacterial cells
binary fission:: rapid asexual production; bacterial chromosome replicates, cell divides, daughter cell is a clone
conjugation:: sex pili form a tunnel between bacteria, copies of chromosomes move from one bacteria to another
transduction:: bacteria acquire new DNA from a phage infection (virus)
transposons:: mobile sections of DNA that replicate themselves, splice themselves out, and insert themselves in another locations; turns genes on and off → genetic diversity
transformation:: bacteria take in plasmids from the environment, sometimes incorporated into the bacterial chromosome, recombinant DNA is formed * ex. if one bacteria cell has resistance to an antibiotic, the resistance can spread to all bacteria in a hospital by releasing its DNA for other bacteria to pick up

plasmid vectors:: plasmids used as tools to clone, transfer, and manipulate genes
reporter genes:: used to visualize that the foreign DNA is incorporated and being expressed in the transformed organism (ex. glowing green protein)
selection genes:: inserted genes that allow for the isolation of the transformed organisms (ex. antibiotic resistant genes)

bacteria are everywhere and in every ecosystem; most species can’t be grown in a lab
thrive anywhere; there are autotroph species and heterotroph species
microbiome:: in humans, affects genes, immunity, health, etc.; improved with probiotics and prebiotic foods
relation to multicellular organisms * parasitism:: some bacteria live in host organisms and obtain food from/at the expense of the host * commensalism:: one organism benefits while the other does not benefit nor is harmed (ex. gut bacteria don’t benefit but humans do) * mutualism:: both organisms, bacteria and host, benefit from the relationship
signal transduction:: how cells respond to substances in their environment with signaling molecules on the surface and inside the cell

viruses aren’t considered to be living because they can’t live or reproduce without a host
have DNA or RNA as genetic material
capsid:: protein shell, encapsulates viral genome
some have membranous envelopes * viral enveloped:: surroup capsid, derived from host membrane, combo of viral and hos molecules
glycoproteins:: on surface of virus, host specific, help virus enter host cell
DNA viruses:: replicate with host cell’s machinery, less mutation because more accurate replication
RNA viruses:: replicate with RNA polymerase, less proofraeding, more mutations, rapid evolution so they are difficult to control with vaccines
phages:: prokaryotic viruses, eat bacteria lawns, specific to bacteria
Lytic Cycle * virulent phages, most common cycle * infection, synthesis, assembly, lytic release * degrades the host DNA, host cell lyses
Lysogenic Cycle * temperate phages * phage DNA splices into chromosome * when cell replicates, phage DNA replicates with it * switches to lytic cycle when conditions change
Retroviruses * RNA genome, use reverse transcriptase to convert DNA and integrate into host cell * attaches, infects, reverse transcriptase, integrate into host DNA, synthesis, assembly * reverse transcriptase is error prone & lacks proofreading, so there is much mutation
viral fossils:: virus infections integrate DNA into our genomes; some end up doing nothing, the integrated viral DNA becomes a part of our own