Practice Exam Flashcards
What are the three types of acellular infectious agents? What are their composition?
Viroid: consist of single, short RNA molecule (ribonucleic acid, yes only contains nucleic acid).
Prions: consist only of proteins
Viruses: nucleic acid within a protein coat
What are the three domains? What distinguishes them?
Bacteria, Archaea, Eukarya
Archaea often live in extremes, are single celled prokaryotes, and DON’T HAVE peptidoglycan
Bacteria are single celled prokaryotes that HAVE peptidoglycan
Eukarya include fungi, algae heminths, protozoa
characterized by membrane bound nucleus
Explain the scientific naming system
“Genus species”
First letter of genus is capitalized, first of species is not
Compare and contrast algae, fungi, protozoa
fungi: use organic material for energy
algae: use photosynthesis
protozoa: use organic material for energy, live in aquatic environments and on other planets, they do not have a rigid cell wall
Gram negative bacteria vs. gram positive bacteria
Gram-negative bacteria: thin layer of peptidoglycan, when gram stained the cells are PINK - has lipopolysaccharide (LPS) which is a molecule on the outer layer of the outer membrane of gram negative
Gram positive bacteria: thick layer of peptidoglycan, when gram stained they are purple
Gram negative bacteria vs. gram positive bacteria
Gram-negative bacteria: yes porin proteins (allows molecules to pass through outer membrane) thin layer of peptidoglycan, when gram stained the cells are PINK - has lipopolysaccharide (LPS) which is a molecule on the outer layer of the outer membrane of gram negative, generally less susceptible to penicillin, no sensitivity to lysozyme; Escherichia, Neisseria, Pseudomonas
Gram positive bacteria: no porin protiens because there is no outer membrane, thick layer of peptidoglycan that contains teichoic acids and lipoteichoic acids, when gram stained they are purple. generally more susceptible to penicillin, sensitivity to lysozyme yes,
bacillus, Staphyloccus, Streptococcus
Shapes of bacteria
two most common:
coccus: spherical (looks like a ball or pearl)
rod: cylindrical (looks like a hot tamale candy) often called a bacillus
vibrio: short, curved rod
spirillum: curved rod long enough to for spirals
spirochete: spiral shaped with a flexible cell wall and unique mechanism of motility
What are the proteins that bind to the bacterial origin of replication
DNA gyrase (helps relieve the tension between strands), helicases
antigenic variation vs. phase variation
random mutations in surface level proteins (antigenic) vs. switching on and off of some genes
How are archaeal cytoplasmic membranes different than bacterial membranes?
the lipid tails of the archaeal membrane lipids are connected to glycerol by a different chemical linkage and are not fatty acids
Bacterial cytoplasmic membrane characeristics
selectivley permeable - O2, CO2, N2, small hydropobic compounds can get across the phospholipid bilayer
some cells using simple diffusion; some use aquaporins to move water across the membrane
Things that do NOT move through: ATP, sugars, ions, amino acids, Macromolecules
Transport Mechanisms:
Facilitated Diffusion (uses concentration gradient)
Active Transport: energy is used to move molecules against the concentration gradient. Uses either transporters that use prton motive force,
or ABC transporters where ATP is used as the energy source and binding proteins deliver a molecule to the transporter.
Group Translocation: the transported molecule is chemically altered as it passes into the cell.
protein secretion
cells actively move certain proteins they synthesize out of the cell and into the surrounding environment
Where does the bacterial cell make its energy as opposed to eukaryotes?
In the cytoplasmic membrane with the electron transport chain (ETC) that creates the proton motive force
(eukaryotes normally make in organelles)
what are the components of peptidoglycan?
NAG (N-acetylglucosamine) NAM (N-acetylmunmic acid) Glycan Peptide Side Chain covalently joined
What does penicillin do?
antibiotic that interferes with peptidoglycan synthesis - functions by preventing the cross linking of adjacent glycan chains 9inhibits enzymes that normally catalyze the cross-linking step
far more effective against gram-positive - because the outer membrane of the gram negative cells prevents the medication from reaching the peptidoglycan layer
What are the two parts of LPS?
Lipid A: anchors the LPS molecule in the lipid bilayer
O antigen: is the part of LPS directed away form the membrane; chain of sugar molecules
What is the periplasm?
the region between the cytoplasmic membrane and the outer membrane; gel-like substance
what does lysozyme do?
enzyme found in tears, saliva and many other body fluids - breaks the bonds that link the alternating subunits of the glycan chains - which destroys the structural integrity of the peptidoglycan molecule - more effective against gram-positive because of the outer membrane on gram negative
flagellin
structural subunit of flagella
sex pili
prelude to DNA transfer
peritrichous flagella
arrangement that surrounds cell
NAATs
nucelic acid probes and nucleic acid amplification tests (NAATs) can both be used to detect nucleotide sequences unique to a given species or related group - each probe dtects only a single possibility
FISH (Fluorescence in situ hybridizaition)
often uses probes that bind 16S ribosomal RNA (rRNA)
Sequencing Ribosomal RNA genes
different prokaryotic rRNAs (5S, 16S, 23S) the 16S is most useful in taxonomy because of its moderate size (1.5k nucleotides). 16S RNA and its eukaryotic counterpart 18S RNA are called small su bunit SS or SSU rRNA
