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51 Cards in this Set

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Viruses
-tiny infectious agents
-need host cell
-consist of a protein coat called capsid
-contain one to several hundred DNA or RNA
-mature virus outside host cell is called virion
-not living organisms
-cant effect cell if specific receptor is not available
Virus is not a living organism because..
-require host cell's reproductive machinery in order to transfer genetic information
-do not metabolize organic nutrients, use ATP from host cell
-possess DNA or RNA not both like all other living organisms
-no cell wall or membrane
bacteriophage
-virus that infects bacteria
-nucleic acid is injected through the tail after viral enzymes digest a hole through cell wall (some virus have enzymes in capsid)
lytic infection
virus commandeers cells reproductive machinery to make new viruses

-attaches, makes hole, injects nucleic acids, replicates,breaks cells apart, forms virion
latent period
-time from infection to lysis in a lytic infection
virulent virus
-virus following lytic cycle
lysogenic infection
-viral DNA is incorporated into the host genome or if virus is an RNA virus it possess reverse transcriptase and DNA is reverse transcribed from RNA and incorporated into host
temperate virus
-virus in a lysogenic cycle
-may show no symptoms of infection and virus is dormant or latent, but it may be activated by stress ultraviolet light or carcinogens
provirus
name for temperate virus aka virus on lysogenic tract whose host cell is bacteria
plus-strand RNA
-proteins can be directly translated from RNA in a virus
-enveloped Plus strand RNA viruses include retroviruses that carries reverse transcriptase
vaccine
-an injection of antibodies or an injection of a nonpathogenic virus with the same capsid or envelope
-allows host to create antibodies
structure of virus
capsid, nucleic acid, lipid rich protein envelope for some viruses,

tail base plate, and tail fibers for most bacteriophages

-bacterium size of mitochondrion and hundreds of viruses fit into one bacterium
Prokaryotes
-no membrane bound nucleus or organelles!
-split into bacteria and archaea (archaea have some in common with eukaryotes)
autotrophs
-capable of using CO2 as sole source of carbon
heterotrophs
-use preformed organic molecules as source of carbon
phototrophs
-organisms that use light as energy
chemotrophs
-use oxidation of organic or inorganic matter
structure of prokaryotes
-dont have nucleus!
-have single circular double strand of DNA
Cocci
round shape of bacteria
bacilli
rod shaped baceria
spirilla
helical shaped bacteria that are rigid
spirochetes
helical shaped bacteria that are not rigid
nucleoid
structure of circular DNA in prokaryotes
prokaryotes and protein
-since protein is translated, they have ribsomes.. (remember viruses dont have ribosomes)
-smaller then eukaryotic ribosomes, made from 50 and 30S sub units to form 70s ribosome
membranes
-made up of phospholipid bilayer
-found surrounding cytosol of nearly all prokaryotes
-composed of phosphate group, two fatty acid chains and glycerol
0amphipathic- both polar and nonpolar
micelle
-when polar ends and non polar ends of an amphipathic membrane line up same way to form spherical structure
integral or intrinsic proteins
ampiphatic proteins that traverse the membrane from the inside of the cell to the outside
peripheral or extrinsic proteins
situated entirely on surface of membrane,and ionically bonded to integral proteins
fluid mosaic model
-model of membrane describing how it is entirely held together by intermolecular force and it is fluid, it can move but cannot separate
facilitated diffusion vs. passive diffusion
facilitated-method of transporting proteins across membrane

passive: if your nonpolar you can pass through membrane without help
bacterial envelope
-surrounds bacterial plasma membrane
-component adjacent to plasma membrane is cell wall
cell wall of bacteria
-prevents protoplase aka plasmamembrane enclosures from birsting

-made of peptidoglycan -series of dissacharide polymre chains with amino acids connected by amino acids, these connections usually are disrupted causing cell wall failure and lyses of bacteria
hypertonic
-characterizes most bacteria
-means that aqueous solution of their cytosol has more particles than of environment
isotonic
cytosol contains same number of particles as environment
hypotonic
cytosol contains less particles than environment
hydrostatic pressure
-builds when water fills a cell,
-eventually stops building when it equals osmotic pressure and equilibrium is reached
gram-positive bacteria
thick peptidoglycan cell wall prevents gram stain from leaking out and cells show up PURPLE
Gram-negative bacteria
-appear pink when gram stained
-do not hold gram stain
-have a phosolipid bilayer outside cell wall (this is not in gram positive bacteria!)
bacteria flagella
long hollow rigid helical cylinders made from globular protein falgellin
-propelled from energy from proton gradeint not ATP
reproduction in bacteria
-cannot sexually reproduce
-alternative forms of genetic recombination include:
-conjugation, transformation, and transduction

asexual reproduction: binary fission
binary fission
-circular DNA is replicated in process similar to replication in eukaryotes
-two DNA polymerases begin at same point on circle (origin of replication) and move in opposite directions making complementary single strands that cmobine with template strands to form two complete DNA double stranded circles
-cell divides giving two genetically identical daughter cells
conjugation
-method of genetic recombination in bacteria
-requires bacteria to have plasmid that codes for sex pilus or bridge to other bacteria (occurs between two bacteria) and DNA is passed from cell with conjugative plasmid to cell without it
MCAT plasmids
-F plasmid or fertility factor
-bacteria with it F+ without it F-
-tranfer occurs from F+ to F-

-R plasmid donates resistance to certain antibiotics

-associate with sex pilus in conjugation for genetic recombination in bacteria
transformation
process by which bacteria may incorporate DNA from the external environment
-may occur to lyses of other bacteria
-typically experiment is when heat killed virulent bacteria are mixed with harmless living bacteria and living bacteria become virulent
transduction
DNA transfer through viruses
-virus that mediates transduction is called vector
fimbriae
-allow bacteria to hold solid objects
lipopolysaccharide layer outside peptidoglycan cell wall of gram negative bacteria purpose:
to protect bacterium against certain antibiotics
Fungi
-have both plant and animal like characteristics
-separated into divisions
-most are considered saprophytic -that is they live off of dead organic matter
-possess cell walls called septa made of chitin (most resistant to microbile attack)
-lack centrioles mitosis occurs in nucleus
-in growth state consist of tangled mass called mycelium of multiple branched hyphae

-are eukaryotic heterotrophs
Fungal Reproduction and life cycle
-alternate between haploid and diploid stages in cycle but haploid predominates
-haploid is their growth stage, hyphae are haploid
-hypae release spores in asexual reproduction
yeasts
-only unicellular fungi
-reproduce asexually by budding where small cell pinches off large cell
conditions determining type of reproduction in fungi
-if conditions are good, fungi reproduce asexually (conditions will be good for offspring too)

-if conditions are tough fungi reproduce sexually because they may not be as bad for sexually reproduced offspring