cell membranes

Question 1

why can the structure of a phospholipid be known as the fluid mosaic model?

Answer 1

fluid - because phospholipid molecules move relative to one another
mosaic - because embedded proteins vary in shape, size and the pattern is like a mosaic

Question 2

what can pass through the membrane?

Answer 2

small, non-polar molecules and lipid-soluble molecules

Question 3

what is the role of the phospholipid?

Answer 3

acts as a barrier, the more polar and larger the molecule - the less likely it is to enter

Question 3

what can’t pass through the membrane?

Answer 3

water-soluble molecules as they must pass through protein channels

Question 4

what is the role of cholesterol?

Answer 4

restricts movement of other molecules making up the membrane and maintains membrane fluidity - the more cholesterol, the more rigid.

Question 5

what’s the purpose of the intrinsic protein?

Answer 5

used for transport into and out the cell via either carrier proteins (active) or channel proteins (passive)

Question 6

what’s the purpose of the extrinsic protein?

Answer 6

its combined with glycogen to create glycoprotein

Question 7

what’s the role of the glycoprotein?

Answer 7

they’re often ‘extrinsic proteins’ and act as antigens or receptors for hormones

Question 8

whats the purpose of glycolipids?

Answer 8

they maintain stability of the cell membrane and are used for cell recognition so they can adhere to other cells to form tissues

Question 9

describe the structure of the cell surface membrane.

Answer 9

hydrophilic phosphate heads - point to and are attracted to water.
hydrophobic fatty acid tails - point away and repel from water.

Question 10

suggest how cell membranes are adapted for other functions.

Answer 10

phospholipid bilayer is fluid so the membrane can bend for vesicle formation/ phagocytosis.
glycoproteins act as receptors/ antigens, involved in cell recognition.