Organization of the Bacterial Cell pt.1

Question 1

What is 16S rRNA / why is it important to the tree of life

Answer 1

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

Question 2

How many regions in 16S rRNA are there that can tolerate mutations

Answer 2

two

Question 3

why does 16S rRNA make a good molecular clock

Answer 3

because it is highly conserved

Question 4

how did carl woese use 16S rRNA to show the divergence of the three domains of life

Answer 4

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

Question 5

which two branches of life are more similar to each other

Answer 5

Archaea and Eukarya

Question 6

what is endosymbiosis

Answer 6

one partner population grow within the body of another organism

Question 7

what does endosymbiosis suggest

Answer 7

reductive evolution

Question 8

what is reductive evolution

Answer 8

essentially co-evolution that led to one of the organisms no longer being able to love on its own - loses unused genes

Question 9

what bacteria was incorporated in pre-animals to create mitochondria

Answer 9

proteobacteria

Question 10

what bacteria was incorporated in pre-plants to create chloroplasts

Answer 10

cyanobacteria

Question 11

what is the gram stain / what is its main purpose

Answer 11

determines which bacteria are gram + or gram - / to classify the bacteria

Question 12

what is the process of the gram stain

Answer 12

1. 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)

Question 13

why does the gram stain turn gram positive cells purple and gram negative pink

Answer 13

the many layers of peptidoglycan in gram positive cells is what the iodine binds to - the more peptidoglycan the more stain retained

Question 14

what are the main components of a bacterial cell from greatest to least respectively

Answer 14

water, proteins, nucleic acids (RNA/DNA), lipids, inorganic compounds

Question 15

in the cell membrane, what motions occur in the lipid bi-layer / which movement is rare

Answer 15

lateral diffusion, rotation, and flexion / flip flop from leaflet to leaflet

Question 16

why is the composition of the outer leaflet and the inner leaflet different

Answer 16

because flip-flop does not occur often

Question 17

what does the cell membrane do

Answer 17

1. site of energy generation 2. effective barrier to polar & charged molecules (permeability barrier)

Question 18

what is an unsaturated fatty acid / how does it affect the permeability of the membrane

Answer 18

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

Question 19

what causes cardiolipin to be produced / what does it do for the cell

Answer 19

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

Question 20

what do hopanoids do / in what cells are they present

Answer 20

provide membrane rigidity and stability / present in bacteria

Question 21

what do archaea use to strengthen their membrane

Answer 21

L-glycerol, ether links between glycerol and fatty acids, cyclopentane rings, crosslinked lipids