Lipids

Question 1

Are lipids polar or non polar molecule

Answer 1

Non polar

Question 2

Lipids are large complex molecules known as […]

Answer 2

Macromolecules

Question 3

Are lipids built from monomers

Answer 3

No
-> instead they have a chain of carbon atoms that act as a backbone

Question 4

What functional group do fatty acid chains contain

Answer 4

(-COOH)
- attached to the hydrocarbon chain

Question 5

Saturated fatty acid chains have no […] bonds and tend to be […] at room temperature

Answer 5

Double, solid

Question 6

Fatty acid chains that have double bonds present between the carbon atoms are called […]

Answer 6

unsaturated

Question 7

What effect does the double bond have on the structure of a fatty acid chain

Answer 7

The double bond causes the molecule to bend or kink: so they are shaped like /—\
+ This stops them being able to pack tighter nicely, making them dense
-> therefore they tend to be oils at room temp

Question 8

Where are hydrogens in the cis arrangement

Answer 8

On the same side of the double bond

Question 9

Where are hydrogens in the trans arrangement

Answer 9

On opposite sides of the double bond

Question 10

How is a triglyceride made

Answer 10

1 glycerol + 3 fatty acid chains
(The length of the hydrocarbon chain is typically 14-16 carbon atoms)
Formed in condensation

Question 11

glycerol + 3 fatty acids ->

Answer 11

triglyceride + 3H2O

Question 12

Glycerol structure

Answer 12

….H
….|
H-C-OH
H-C-OH
H-C-OH
….|
….H

Question 13

The reaction between alcohol and carboxylic acid functional groups is called […]

Answer 13

esterification

Question 14

Ester functional group

Answer 14

-COO

Question 15

an ester bond is the bond between

Answer 15

The oxygen and carbons that connect the molecules

Question 16

Triglycerides can be broken down in

Answer 16

Hydrolysis

Question 17

Note 2 go look at formation of a triglyceride (drawn out)

Answer 17

👎👎👎

Question 18

What are phospholipids

Answer 18

Modified triglycerides

Question 19

Difference between triglycerides and phospholipids

Answer 19

In phospholipids, one of the fatty acid chains is replaced by an inorganic phosphate ion (PO43-)

Question 20

Is a phospholipid molecule polar or non polar

Answer 20

Polar

Question 21

Phospholipids have 2 hydrophobic, non polar

Answer 21

Fatty acid tails

Question 22

Phospholipids have a charged (polar), hydrophilic

Answer 22

Phosphate head

Question 23

Why are phospholipids called surfactants

Answer 23

They form a 2 layered sheet formation (bilayer)
-> hydrophobic tails inwards, hydrophilic phosphate head outwards to the aq environment
—> this separates the cytoplasm from the outer aq area

Question 24

Why is the bilayer arrangement of phospholipids important

Answer 24

Allows them to separate the aqueous environment + then allows formation of membrane bound organelles

Question 25

What are sterols

Answer 25

Steroid alcohols
-> another type of lipid

Question 26

Sterols structure

Answer 26

• complex alcohol molecules based on a four ring structure, with a hydroxyl group at one end
• The hydroxyl group is polar and hydrophilic, and the rest of the molecule is hydrophobic

Question 27

The body manufactures cholesterol primarily in the […]

Answer 27

liver and intestines

Question 28

What does cholesterol do in the cell membrane

Answer 28

-> It adds stability to the cell membrane and regulates their fluidity
•At low temperatures it keeps the membrane fluid
•At high temperatures it stops it becoming too fluid

Question 29

how the properties of cholesterol molecules relate to their functions in living organisms

Answer 29

• in eukaryotic cells
  cholesterol molecules help
  support the structure of the
  cell membrane and stabilise
  the cell membrane
• has a small size and
  flattened shape which allows
  it to fit in between the
  phospholipid molecules in the
  membrane
• their non-polar hydrophobic
  tail is attracted to the
  phospholipid hydrophobic
  tails in the centre of the
  membrane, packing the
  phospholipids closer together
  making adding stability to the
  membrane and regulating the
  fluidity of the membrane
• the hydroxyl group is polar
  and therefore hydrophilic
  and the rest of the molecule is
  hydrophobic, so it’s able to
  create a further barrier

Question 30

how the properties of triglyceride molecules relate to their functions in living organisms

Answer 30

energy storage in plants
and animals
- some bacteria use
triglycerides to store both
energy and carbon
- good for storage because
long hydrocarbon tails of the
fatty acids contain lots of
chemical energy - lots of
energy is released when
they’re broken down
- 2x more energy than
carbohydrates because of tails
- insoluble so don’t cause
water to enter the cells
- Storage molecules need to
be insoluble so they don’t
release their contents when in
contact with water
- triglycerides bundle
together as insoluble droplets
in cells because the fatty acid
tails are hydrophobic - the
tails face inwards shielding
themselves from water

Question 31

how the properties of phospholipid molecules relate to their functions in living organisms

Answer 31

found in the cell membranes
of all prokaryotes and
eukaryotes
- make up the
phospholipid bilayer
- hydrophilic heads and
hydrophobic tails, so they
form a double layer with their
heads facing out towards the
water on either side
- the centre of the bilayer is
hydrophobic so water soluble
substances can’t easily pass
through it - acts as a barrier