Mesnage - Cell structure and function in bacteria Flashcards
name the 5 shapes of bacteria
cocci rods curved spiral exotic
name 2 advantages of viruses being small
increases surface area: volume ratio which means:
1) nutrient exchange is more efficient because there is a greater SA to ‘catch’ nutrients
2) greater turnover rate = rapid evolution
what are the two possible results of a gram stain and what do they mean?
purple = positive= stained by crystal violet, which binds to peptidoglycan pink = negative = stained by safarin therefore no thick peptidoglycan wall
name the components of a gram (+) bacterial cell envelope
s-layer; crystalline structure of protein/glycoprotein
capsule; consists of slippery layer of polysaccharides which can prevent phagocytosis by WBCs and keeps the environment hydrated
exopolysaccharides; polysaccharides used for biofilm formation
name the components of a gram (-) bacterial cell envelope
lipoprotein and lipopolysaccharide membrane (inner and outer); phospholipids, porins and other proteins, LPS (endotoxin), unsat fats for solubility some gram(-) also contain s-layer and capsule
name the 2 repeating units in peptidoglycan and the function of peptidoglycan
units; N-acetylglucosamine + N-acetylmuramic acid
function; dynamic regulation of exchanges with env +
scaffold for the display of polymers and proteins
name 4 components of the cytoplasmic membrane
phospholipids
hopanoids (like sterols in eukaryotes)
proteins (transporters/sensors)
unsat f/a’s to moderate fluidity and permeability
name 2 properties of chromosomes specific to bacteria
always dsDNA
DNA in nucleoid is in a tangled circle and wrapped around histone-like proteins
name 4 properties of plasmids specific to bacteria
always dsDNA
usually circular
can be used in horizontal gene transfer
carries resistance genes
name 3 specific properties of bacterial gene structure
no introns
use of operons
genes relatively small compared to eukaryotes
list the stages of transcription in bacteria
RNA polymerase scans sequence of DNA (loose complex), sigma factor recognises upstream promoter sequence and forms close complex with RNA pol.
DNA unwinds -> open complex -> sigma factor of RNA pol released
GC rich termination hairpin OR rho protein termination removes RNA pol from the DNA transcript
list the differences in translation between bacteria and eukaryotes
prok: 70s ribosome binds mRNA (more efficiently with tRNA present)
euk: 80s ribosome binds mRNA (more efficiently without tRNA present
prok: 30s subunit recognises the Shine Delgarno sequence
euk: 40s subunit guided by the 5’ prime cap on mRNA
prok: transcription coupled to translation
what are the prefixes for the organisms that use sunlight or preformed molecules as energy sources?
sunlight: photo
preformed: chemo
what are the prefixes for the organisms that use organic or inorganic molecules as an electron source?
organic; organo
inorganic; litho
what are the prefixes for the organisms that use organic or inorganic molecules as a carbon source?
organic: heterotropic
inorganic: autotropic
