Molecules - Phospholipids And Cholesterol

Question 1

Phospholipid

Answer 1

Molecule consisting of glycerol, 2 fatty acids and Phosphate group

Question 2

Phospholipid structure

Answer 2

Same as triglyceride except one fatty acid replaced by a phosphate group

Condensation reaction between OH group of Phosphate and 0H group of glycerol

Ester bond

Most fatty acids have even number of carbon atoms. Commonly one of these chains is saturated and one unsaturated

Question 3

Phospholipid behaviour in water

Answer 3

Phosphate group has -ve charge —- polar head - hydrophilic

Fatty acid tails non- polar —— tail - Hydrophobic

Meaning phospholipid molecule is and the p meaning phospholipid molecule is amphipathic

Membrane lipids usually amphipathic
Storage one is not

Phospholipids may form micelles in water

Question 4

Phospholipid bilayer

Answer 4

Amphipathic phospholipids gd membranes

Form bilayer when aquatic solution inside and out, tails in , heads out

Question 5

Phospholipid bilayer structure

Answer 5

Individual phospholipids free to move around in the air but tail never exposed to water giving membrane stability

Membrane is selectively permeable. Only small nonpolar molecules move through the tails in the bilayer
— membrane controls what goes in and out of cells, and keeps it functioning properly

Question 6

Cholesterol

Answer 6

Steroid alcohol ( sterol)

Four carbon-based rings (isoprene units)

Small hydrophobic molecule , sits in hydrophobic part of bilayer

Regulate fluidity of membrane

Made in liver and animals

Plants have stigmasterol instead , Double Bonds between carbon 22 and carbon 23

Question 7

Steroid hormones

Answer 7

Testosterone , oestrogen, and vitamin d = cholesterol based so I can pass through the hydrophobic part of the cell membrane

Steroids also abundant in plants and on ingestion and absorption some can be converted into animal hormones