Transport across the cytoplasmic membrane Flashcards
what is passive diffusion
the movement of molecules from higher concentration to lower concentration without the use of energy
what is facilitated diffusion
when molecules move from higher concentration to lower concentration through a permease without the use of energy
what examples of molecules can move by passive diffusion
O2, H2O,CO2
What is the saturation effect observed in carrier-mediated transport systems?
Carrier-mediated transport systems have an increase in rate of uptake until fully saturated
describe the three classes of membrane transporters
Uniporters: transport molecules in one way.
Antiporter: transport molecules simultaneously in two different directions.
Symporter: transport molecules simultaneously in the same direction.
what is an example of a symporter
Lac permease in E. coli.(Lacotse and H+ into the cell)
what is an example of antiporter
Sodium-calcium exchanger
what are the three main classes of transport in prokaryotes?
Simple transport(proton motive force)
ABC system
Group translocation
Explain the active transport
this is the process of moving molecules against their concentration gradient
what does ABC stand for?
ATP Binding Cassette
what type of substrate specificity does ABC have
high substrate specificity
Examples of molecules that are moved in the ABC system
sugar. amino acids
what are the components of the ABC system
periplasmic binding protein (sugar or solute binding protein)
integral binding protein (permeases binding protein)
ABC protein that provides ATPase function
gram positives employ what type of substrate binding proteins
lipoproteins
ATP binding cassette is located where for a gram negative bacteria
in the periplasm
ATP binding cassette is located where for a gram positive bacteria
in the cell membrane
briefly explain the ATP binding cassette
a solute diffuses into the periplasm and binds to a solute binding protein. the solute then binds to the integral membrane protein. ABC protein hydrolyses ATP to ADP before the solute is translocated to the cytoplasm.
what does the hydrolysis of ATP provide
energy for the translocation of the solute
what is group translocation
a molecule is chemically altered as they cross the membrane
what is the PTS
phosphotransferase system
PTS uses what as an energy source
PEP (phospho-enol-pyruvate.)
what are the common components of the PTS and where are they located
enzyme i(cytosolic)
HPr(cytosolic)
what are the specific components of the PTS
enzyme iia(cytosolic)
enzyme iiib(cytosolic or membrane)
enzyme iiic(membrane)
briefly explain the PTS
PEP donates its phosphate group to enzyme i to become EI-P which then donates the phosphate group to HPr which then becomes HPr-P then donates its phosphate group to EIIA to become EIIA-P then to EIIB to become EIIB-P then finally to glucose which becomes glucose-6-phosphate
what is the purpose of phosphorylation
to prevent it from diffusing out of the cell
what is the function of the cell wall in a bacteria cell
to prevent osmosis lysis
to prevent toxic substances
helps to evade host immune system
what are the two layers in a gram negative bacteria cell wall
lipopolysaccharide
peptidoglycan
what are the components of peptidoglycan
N-acetylglucosamine and N-acetylmuramic
Amino groups
lysine or diaminopimelic acid(DAP)
form glycan tetrapeptide
the glycan backbone is made up of
N-acetylglucosamine
N-acetylmuramic
how are the two sugars that make up the glycan backbone linked together
beta(1,4) glycosidic linkages
what consists of the tetrapeptide side chain
l-alanine
D-glutamic acid
DAP or l-lysine
D-alanine
teichoic acids are common to what type of bacteria
gram positive
what are the components of teichoic acids
glycerol phosphate or ribitol
D-alanine
D-glucose
crosslinks in the peptidoglycan are formed by
peptide bonds
what is the purpose of the helical arrangement
for 3-D crosslinking
thermoplasma are species of what prokaryotes
archaea
what are lipoteichoic acids
teichoic acids connected to membrane lipids
list the names of inclusion bodies
carbon storage polymers
sulfur globules
polyphosphate
magnetosomes
what are the examples of carbon storage polymers
glycogen
poly-beta-hydroxybutyric acid
PHB and glycogen are what type of storages respectively
lipid storage
glucose polymer
magnetosomes have what as their intracellular granules
Fe3O4
Fe3S4
the ability of bacteria to rotate round the earth’s magnetic field
magnetotaxis
endospores are only produced by what type of bacteria
gram positive
what are the protective features of the endospore
the layers and core
what consists of the layers in an endospore
spore coat and cortex
what is the name of the acid found in the core of an endospore
ca-dipicolinic acid and SAPs
monotrichous
single flagellum
amphitrichous
opposite sides of flagellume
lopotrichous
multiple around a single tut
peritrichous
round the cell
what are the components of a flagellum
filament
hook
basal body
what is the hook
couples the filament and basal body
what is the filament
a rigid helical protein structure composed of flagellin(protein subunits)
what is the basal body
a central rod that passes through rings
what are the rings in the basal body
L ring: located in the LPS
P ring: peptidoglycan
MS ring: located in the membrane
C ring: located in the cytoplasm
energy to turn the flagella on
comes from the proton motive force
Mot proteins are what
they form channels to allow the H+ enter the cell from the cytoplasm
chemotaxis
response to chemicals
aerotaxis
response to oxygen
phototaxis
response to light
osmotaxis
response to ionic strength
hydrotaxis
response to water
what is a capsid
a protein coat that surrounds the virus and allows the transfer of the genome
icosahedral capsid has how many faces
20 triangular faces
example of a virus with a binal capsid
T4 bacteriophage of E.coli
which bacteria has an icosahedral head
human papillomavirus
mimivirus infects what kind of organism
amoeba
what are the two major spikes on virus’ envelope
hemaglutanin
neuraminidase
what is lytic infection
when the virus accumulates in the cell and lysis the cell
what is persistent infection
when the virus pushes through the host cell being released by budding. it doesn’t kill the host cell
what does neuraminidase help the virus do
exit the host cell
