Lipids

Question 1

Triglyceride=

Answer 1

1 glycerol
3 fatty acids (hydrophobic tails)
Ester bond

Question 2

Triglyceride uses

Answer 2

-insulation
-energy store
-membranes
-energy source
-protection
-hormones

Question 3

Fatty acids saturated

Answer 3

No double bonds between c-c
Straight

Question 4

Fatty acids unsaturated

Answer 4

Double bonds between c=c
Kinky

Question 5

Triglyceride properties

Answer 5

Energy storage
Insoluble in water-no effect on WP
Bundle as drops -Micelles

Question 6

Phospholipids

Answer 6

2 fatty acids+ glycerol+ phosphate group (negatively charged=polar)=hydrophilic

Question 7

3 polysaccharides?

Answer 7

starch, cellulose, glycogen

Question 8

what kind of bonds are found in polysaccharides?

Answer 8

Glycosidic

Question 9

Name the monomer that makes up starch

Answer 9

a-glucose

Question 10

Name the two polysaccharide chains that make up starch

Answer 10

amylose and amylopectin

Question 11

What does cellulose form when chains group together? Which bonds are involved in holding these together?

Answer 11

microfibrils/macrofibrils/fibres Hydrogen bonds

Question 12

One similarity and one difference between starch and
glycogen

Answer 12

Similarity:
Both made of a-glucose
Both energy storage
Both insoluble/large/can’t diffuse out of cells
Difference: starch – plants, glycogen – animals; starch stains blue/black with iodine; branched and coiled chains in starch, only branched in glycogen

Question 13

Properties of triglycerides

Answer 13

• Insolubleinwatersotheydon’taffectthe water potential of the cell and cause water to enter the cells by osmosis (which could cause them to swell)
• Triglyceridesalwaysbundletogetheras insoluble droplets in cells as the fatty acid tails are hydrophobic - the tails face inwards shielding themselves from water with glycerol heads on the outside

• Mainly used as energy storage molecules • The long hydrocarbon tails of the fatty
acids contain lots of chemical energy
• This means lipids contain about x2 as much energy as carbohydrates

Question 14

Properties of phospholipids

Answer 14

• Makeupcellmembranes-phospholipid bilayer
• Controllingwhatenters/leavesthecell
• Phospholipidheadsarehydrophilic
• Thetailsarehydrophobic
• Formingadoublelayerwithheadsonthe outside
• Thecentreishydrophobic,meaningwater soluble substances cant easily pass through

Question 15

One similarity and one difference between the structure phospholipids and triglycerides

Answer 15

Similarity:
Both made of glycerol Both contain fatty acids
Difference:
Phospholipids have 2 fatty acids and triglycerides here
Phospholipids have a phosphate group

Question 16

Cellulose

Answer 16

Cellulose is made up of β 1-4 glucose molecules. Each alternate glucose molecule flips 180° to allow the bonding of the hydroxyl groups. This means that the CH2OH alcohol group of every other molecule is above the carbon ring, and the others are below.

Question 17

Where is oh on alpha glucose

Answer 17

Bottom

Question 18

Lipid digestion

Answer 18

• Bile salts emulsify lipids into micelles to increase surface area and solubility in water
• Lipids/triglycerides are hydrolysed by lipases to form fatty acids and monoglycerides
• Micelles contain bile salts and fatty acids/monoglycerides, making them soluble in water.
• Fatty acids/monoglycerides are released to cell/lining of the ileum.
• This maintains a higher concentration of fatty acids/monoglycerides outside the cell, so they are absorbed by simple diffusion.
• Triglycerides are reformed in cells and form chylomicrons.
• The chylomicron vesicles fuse with the cell membrane and are released by exocytosis.

Question 19

Lipid digestion

Answer 19

• Bile salts emulsify lipids into micelles to increase surface area and solubility in water
• Lipids/triglycerides are hydrolysed by lipases to form fatty acids and monoglycerides
• • Micelles contain bile salts and fatty acids/monoglycerides, making them soluble in water.
• Fatty acids/monoglycerides are released to cell/lining of the ileum.
• This maintains a higher concentration of fatty acids/monoglycerides outside the cell, so they are absorbed by simple diffusion.
• Triglycerides are reformed in cells and form chylomicrons.
• The chylomicron vesicles fuse with the cell membrane and are released by exocytosis.

Question 20

Lipid digestion

Answer 20

• Bile salts emulsify lipids into micelles to increase surface area and solubility in water
• Lipids/triglycerides are hydrolysed by lipases to form fatty acids and monoglycerides
• Micelles contain fatty acids, monoglycerides and bile salts
• They move through the ileum to the epithelium ce

Question 21

Lipid absorption

Answer 21

• Micelles contain fatty acids, monoglycerides and bile salts. They make fatty acids soluble in water and move through the ileum releasing the monoglycerides and fatty acids
• Monoglycerides and fatty acids are non-polar so move through the membrane easily into epithelial cells by diffusion
• Monoglycerides and fatty acids are reformed into triglycerides in the ER
• In the golgi the triglycerides combine with lipoproteins and cholesterol to form chylomicron vesicles
• Chylomicrons move across the cell membrane by exocytosis and enter lymph vessels called lacteals
• They eventually move from the lymph to the blood where they are hydrolysed in the endothelium and diffuse into cells