Bacteria and archaea cell membrane structure Flashcards
What 2 structures make up the cell envelope?
The cell membrane and cell wall
What does the cell membrane do in bacteria?
Selective barrier that keeps the outside out and the inside in
What are bacterial cell membranes made out of?
Phospholipids, proteins, carbs
What is the structure of a phospholipid?
A glycerol with a phosphate attached to one carbon, and fatty acids attached to the other two. Small polar head group attached to the phosphate
What are hopanoids?
Rigid, planar molecules analogous to sterols in eukaryotic membranes, but aren’t sterols even though they look like one
What do hopanoids do?
Stabilize bacterial membranes and regulate fluidity. Prevents phospholipids from packing too tightly in low temps and stops them becoming too loose in high temps
What type of bacteria tend to have hopanoids in their membranes? Why?
Soil bacteria. They’re exposed to a wide range of temperatures
What is the only bacteria that has cholesterol in its membrane? Why?
Mycoplasma. They’re intracellular pathogens with no cell walls, so they use cholesterol to strengthen their membranes
Where does Mycoplasma get its cholesterol?
Steals it from the host. No bacteria has been found to make cholesterol
What are the 2 types of membrane proteins?
Integral and peripheral
What are two ways archaeal membrane lipids are different than bacterial lipids?
Ether linkages instead of ester linkages and phytanyls instead of fatty acids
How do archaea attach the hydrophobic tails of their phophoslipids to the glycerol?
Ether linkages
Why do archaeal membrane lipids have ether linkages instead of ester linkages like bacteria?
Ether linkages are more stable in extreme conditions. Keeps the archaeal membranes stable at high temps
What do archaeal membrane lipids use instead of fatty acids?
Phytanyl groups
What are phytanyl groups made of?
4 isoprene units stuck together
