Structure And Function

Question 1

Membranes are and allow what?

Answer 1

Allows communication with others, they are fundamental to cell theory.

Question 2

Problem with the term ‘cell membrane’

Answer 2

Cells have many cell membranes, so there is different specific names needed, e.g plasma refers solely to the cell surface membrane.

Question 3

What is compartmentalisation?

Answer 3

The formation of separate membrane- bound areas in the cell allowing: metabolic reactions to be separated, chemical concentration gradients can be made, with protection of cellular components.

Question 4

Roles and info of membranes

Answer 4

Membranes are flexible (allowing fluidity) allowing them to break and fuse easily, it provides a fix set of conditions inside the cell cytosel (homeostasis), it provides a PARTIALLY permeable membrane allowing transport of substances through the barrier (exocytosis and endocytosis) also cell signalling: having proteins on which act upon each other.

Question 5

Structure of membranes

Answer 5

Membranes are mainly phospholipids, with a hydrophilic head containing a phosphate group, phosphoester bonds. glycerol is the backbone allowing the tails to join through the ester bonds. A hydrophobic tail consisting of an ester bond and a fatty acid tail. Head is polar and tails are non-polar, phospholipids are classed as amphipathetic - containing both hydrophobic and hydrophilic parts of a protein.

Question 6

Arrangement of phospholipid

Answer 6

Spontanoulsly arrange in a bilayer, the hydrophilic tails face inwards and are shielded from the surrounding polar fluids, the two hydrophilic head regions associate with cytosolic and extracellular fluids.

Question 7

Phospholipid billayer structural Properties

Answer 7

Held together in a billayer by hydrophobic interactions, Fluidity allows for the breaking/remaking of membranes (exocytisis/endocytosis)

Question 8

The fatty acid tails

Answer 8

The fatty chains in phospholipids and glycolipids usually contain an even number of carbon atoms being the most common (16 and 20) and (16 and 18) , they may be saturated or unsaturated.

Question 9

Cell signaling

Answer 9

Where cells interact with others, a molecule causes a change in another cell.

Question 10

Carrier protein

Answer 10

Carrier proteins bind specific solute to be transferred across the lipid billayer, denatured by high proteins, the protein shape changes allowing molecules to diffuse through

Question 11

Channel protein

Answer 11

Allows protein and ion molecules, acting like a pore in the membrane. Molecules travelsl through at a much quicker rate.