2.6 Lipids

Question 1

what is a lipid (3)

Answer 1

• contains more energy per gram than other biological molecules
• insoluble (do not dissolve in water)
• hydrophobic

Question 2

name 3 lipids and describe them

Answer 2

1. fats and oils: energy storage molecules in organisms
2. phospholipids: form membrane that separate cell from extracellular and intracellular environments
3. steroids: large class of lipids that include sec hormones

Question 3

what is a fat

Answer 3

lipid that is from animal origin solid at room temp

ex) lard, butter

Question 4

what is an oil

Answer 4

lipid that is plant origin liquid at room temp

ex) corn oil, soybean oil

Question 5

name 3 functions of fats

Answer 5

1. long term energy storage
2. insulated against heat loss
3. protective cushion around major organs

Question 6

what is a triglyceride

Answer 6

fat molecule because of three part structure; 1 glycerol molecule + 3 fatty acids

Question 7

what is neutral fat

Answer 7

term used for triglyceride because molecule is nonpolar

Question 8

what are emulsifiers

Answer 8

contain molecules with a nonpolar and polar end

Question 9

a) describe the process of emulsification

b) name an example

Answer 9

a) emulsifier molecules position themselves around oil droplet so non polar ends project onwards and polar ends project outwards which causes fat/oil to disperse in water
b) washing dirty clothes w soap, salad dressing consistency (two layers and uniform consistency), fats emulsified by bile in intestines before digested, liver produces bile then stored in full bladder

Question 10

what is a fatty acid

Answer 10

hydrocarbon chain that ends in acidic group -COOH (most fatty acids in cells contain 16 or 18 carbon atoms per molecule)

Question 11

what is a FATTY

Answer 11

the person reading this

Question 12

what is a

a) saturated fatty acid
b) unsaturated fatty acid

Answer 12

a) saturated: no double covalent bond accounts for solid nature of fat (lard and butter) at room temp
b) unsaturated: double bonds between carbon atoms where hydrogen is less than two per carbon accounts for liquid state of vegetable oils at room temp

Question 13

what is the difference between a unsaturated cis fat and unsaturated trans fat

Answer 13

configuration of hydrogen atom in the double bonded unsaturated fat

Question 14

a) what are trans fats

b) why is this used and where are they found

Answer 14

a) produced by hydrogenation (the process of chemically adding hydrogen to vegetable oils)
b) used to convert fat into solid, found in processed foods

Question 15

what is a phospholipid

Answer 15

lipid that is constructed of 1 glycerol, 2 fatty acids, 1 phosphate group/groupings that contains phosphate and nitrogen

Question 16

describe the components of a phospholipid

Answer 16

1 polar head: hydrophilic, soluble in water// face outwards towards water solutions

2 nonpolar tails: hydrophobic, non soluble in water// tails form hydrophobic interior

Question 17

describe the function of a phospholipid in the plasma membrane

Answer 17

(in aqueous environment)

• form bilayer which hydrophilic head face outwards toward watery solution and tails form hydrophobic interior
• separate extracellular and intracellular environments vital to form and function of a cell

Question 18

what is a steroid

Answer 18

lipid that has four fused carbon rings differing in the arrangements of atoms and type of functional group attached to them

Question 19

a) what is cholesterol

b) what are its functions (2)

Answer 19

a) a steroid formed by the bush that also enters the body as part of our diet
b) 1. component of animal cell plasma membrane
2. precursor of several other steroids like bile salts, sex hormones testosterone and estrogen

Question 20

why is a diet high in saturated fats, trans fats, cholesterol dangerous

Answer 20

can cause fatty material to accumulate inside the lining of blood vessels and reduce blood flow

Question 21

what are waxes and describe its structure

Answer 21

lipids that protect from water loss and help energy storage in plankton

• long fatty acids attached to alcohol
• solid at roomo temperature