cell membrane structure + function

Question 1

fluid mosaic model

Answer 1

fluid - not a solid barrier, selectively permeable
mosaic - mixed composition primarily of phospholipids (lipids) and proteins.

Question 2

how are the phospholipids arranged?

Answer 2

phospholipid bilayer - one set of phospholipid (phosphate head + fatty acid tails) + another set of the same thing upside down. tails face each other and the phosphate heads face the inside and outside of the cell.

Question 3

structure of a phospholipid

Answer 3

• phosphate head (hydrophilic, polar/attracted to water)
• fatty acid tails (hydrophobic, non-polar/repellent of water)

Question 3

proteins

Answer 3

• proteins on the surface/proteins that do not go through the membrane entirely: peripheral proteins, act as markers/receptors
• proteins embedded in the bilayer/go through: integral proteins that transport substances too large or charged to go through the membrane or going against the concentration gradient (L -> H instead of H -> L)

Question 3

two main components of a cell membrane

Answer 3

proteins + lipids

Question 3

transport proteins

Answer 3

• go through membrane
• interior able to open to both sides
• may change shape as they interact with solute
• move water soluble (polar) substances
• may be passive or active (usage of ATP)
• transport large, charged, or against-gradient substances

Question 4

cell membrane function

Answer 4

• creates barrier between the inside and outside of cell: MAINTAINS HOMEOSTASIS within the cell