lipids

Question 1

why fats that contain unsaturated fatty acids are liquid at room temperature?

Answer 1

kinks in their fatty acid tail, cannot pack closely together, less extensive weaker hydrophobic interactions
less heat/energy required to disrupt hydrophobic interactions to bring about a change in state

Question 2

properties of triglycerides (5)

Answer 2

good energy source
-more than twice amount of energy in form of ATP released from oxidation
good energy storage
- contain more energy per gram than either carbo/proteins, most weight efficient
-large and non polar, insoluble
source of metabolic water
- higher proportion of hydrogen
thermal insulation
-conduct heat slowly, reducing heat loss from the body
buoyancy
-less dense than water

Question 3

arrangement in cell membrane

Answer 3

polar hydrophilic phosphate head of phospholipids face outwards and interact with the aqueous medium
non-polar hydrophobic fatty acid tails face inwards and are shielded from the aqueous medium

Question 4

selective barrier in cell membrane

Answer 4

hydrophobic core of cell membrane acts as a selective barrier between the aqueous interior and exterior of the cell, restricting the movement of charged ions and polar molecules across the membrane

Question 5

membrane fluidity in cell membrane

Answer 5

non-polar fatty acid tails of phospholipids allow the phospholipids to be held together by weak hydrophobic interactions
unsaturated fatty acid tails of phospholipids have kinks that keep the phospholipids from packing closely together