Organization of the Bacterial Cell pt.1 Flashcards
What is 16S rRNA / why is it important to the tree of life
it is a small-subunit of rRNA and it is highly conserved across all organism which makes it the perfect thing to track throughout organisms to make the tree of life
How many regions in 16S rRNA are there that can tolerate mutations
two
why does 16S rRNA make a good molecular clock
because it is highly conserved
how did carl woese use 16S rRNA to show the divergence of the three domains of life
he used the sequence divergence of the variable regions of 16S as a proxy of genetic relatedness - the phylogenetic trees he made indicate the divergence (number of differences) between sequences
which two branches of life are more similar to each other
Archaea and Eukarya
what is endosymbiosis
one partner population grow within the body of another organism
what does endosymbiosis suggest
reductive evolution
what is reductive evolution
essentially co-evolution that led to one of the organisms no longer being able to love on its own - loses unused genes
what bacteria was incorporated in pre-animals to create mitochondria
proteobacteria
what bacteria was incorporated in pre-plants to create chloroplasts
cyanobacteria
what is the gram stain / what is its main purpose
determines which bacteria are gram + or gram - / to classify the bacteria
what is the process of the gram stain
- add methanol to fix cells to the surface 2. add crystal violet stain (reversible) 3. add iodine (binds stain to gram positive cells 4. wash with ethanol 5. add safranin (turns gram negative pink)
why does the gram stain turn gram positive cells purple and gram negative pink
the many layers of peptidoglycan in gram positive cells is what the iodine binds to - the more peptidoglycan the more stain retained
what are the main components of a bacterial cell from greatest to least respectively
water, proteins, nucleic acids (RNA/DNA), lipids, inorganic compounds
in the cell membrane, what motions occur in the lipid bi-layer / which movement is rare
lateral diffusion, rotation, and flexion / flip flop from leaflet to leaflet
why is the composition of the outer leaflet and the inner leaflet different
because flip-flop does not occur often
what does the cell membrane do
- site of energy generation 2. effective barrier to polar & charged molecules (permeability barrier)
what is an unsaturated fatty acid / how does it affect the permeability of the membrane
unsaturated fatty acid has double bonds in the fatty acid (mostly cis) / leads to a less rigid formation of the lipids so it becomes more permeable and fluid
what causes cardiolipin to be produced / what does it do for the cell
alteration in stress or starvation / supports the concavity of the cell and helps the cell get smaller and more round - can interact with proteins and change their function to benefit the cell in stressful situations
what do hopanoids do / in what cells are they present
provide membrane rigidity and stability / present in bacteria
what do archaea use to strengthen their membrane
L-glycerol, ether links between glycerol and fatty acids, cyclopentane rings, crosslinked lipids
