5. Lipids

Question 1

Which side of lipids are hydrophobic and hydrophilic?

Answer 1

hydrophobic fatty acid tails, hydrophilic heads

Question 2

Know micelle, liposome and phospholipid bilayer

Answer 2

Know them structures. Micelles make soap bubbles

Question 3

Saturated fatty acid vs unsaturated fatty acid. Which one is better for membrane fluidity?

Answer 3

made up of single bonds vs made up of double bonds –> kinks –> hard for them to stack and solidify; better for membrane fluidity

Question 4

How are lipids’ solubility and melting temp determined?

Answer 4

longer chain –> higher melting temp and lower solubility; more double bonds –> lower melting temp

Question 5

What are glycerophospholipids? How are they named?

Answer 5

phospholipids with glycerol backbone with ester linkages to 2 fatty acids and phosphodiester linkage to 1 highly polar head group. They’re named according to their head group (ex: phosphatidyl-“head group”)

Question 6

What are sphingolipids? What are the 4 subclasses?

Answer 6

phospholipids with SPHINGOID backbone with long nonpolar fatty acid tails and polar head groups; they’re used in ABO blood typing system. Ceramide (has H has head group and only has actual spingosine backbone), sphingomyelins (has phosphodiester bond => phospholipid), glycosphingolipids (has no phosphodiester bond, has glycosidic bond => not a phospholipid), gangliosides (has no phosphodiester bond, has glycosidic bond => not a phospholipid)

Question 7

What are waxes made up of?

Answer 7

esters of long fatty acid chains with long chain alcohols

Question 8

Know the structure of triglycerides. Know their purpose and what type of bond and type of rxn bond makes. Know chylomicron

Answer 8

3 fatty acid chains + glycerol (a 3 C alc)
dehydration –> 3 water molec released
ester bond
Purpose: storage lipids
Chylomicron = lipoproteins consisting of triglycerides, phospholipids, proteins and cholesterol

Question 9

Know the basic structure of steroids. Know basic description of steroid hormones

Answer 9

3 cyclohexane rings and 1 cyclopentane ring. Produced in endocrine glands, travel in bloodstream to high-affinity receptor in nucleus

Question 10

What are fatty acids made up of? How are they bonded?

Answer 10

CA + long hydrocarbon (C-H) chain via ester bond

Question 11

What type of rxn is making a phosphodiester bond? What’s the difference b/w alpha vs beta glycosidic bonds?

Answer 11

dehydration

both groups = same side vs both groups = opposite sides

Question 12

What is the only FA humans can synthesize? Where is it formed?

Answer 12

Palmitic acid made of 16 carbons. Produced in cytoplasm from 8 acetyl CoA that’s been transported out of mitochondria, 7 ATP, and 14 NADPH

Question 13

How does keto genesis occur?

Answer 13

Prolonged starvation, excess acetyl CoA in liver, beta [O] occurs in mito matrix

Question 14

Terpenes

Answer 14

Class of lipids built by isoprene, monoterpene = 2 isoprene units; precursor to steroids, cholesterol and ear wax; can create terpenoids like vit A

Question 15

Big thing about cholesterol?

Answer 15

Found in cell membrane and is responsible for fluidity: prevents from solidifying at low temps and prevents too much permeability at high temps; they’re amphipathic; they’re steroid hormone precursors. They have the four ring steroid structure. They help make bile in liver

Question 16

What are prostaglandins? What can prevent their production?

Answer 16

Unsaturated CAs derived from arachidonic acid that act as autocrine and paracrine signal molecs; they help regulate synthesis of cAMP; also help with inflammation, pain and smooth muscle function. NSAIDS like aspirin

Question 17

How are vitamins synthesized, name 2 categories and list examples of fat soluble vitamins

Answer 17

Can’t synthesize them, get them thru diet; water soluble that can be excreted thru urine and fat soluble that can be stored in fat; A, D, E and K

Question 18

Vitamins A vs D vs E vs K

Answer 18

Carotene; vision, growth, immunity; retinal = most important vit A metabolite, stored as retinol which can be oxidized to retinoic acid to regulate epithelial development vs cholecalciferol from UV light, can be converted to calcitriol in liver and kidneys; lack of D results in rickets: long curved bones and impede growth vs tocopherols and tocotrienols; antioxidants vs phylloquinone and menaquinone; post translational modification of prothrombin, coagulation

Question 19

Saponification

Answer 19

Ester hydrolysis of triacylglycerols using a strong base

Question 20

Why is more energy stored as fats than glycogen?

Answer 20

Fats are more reduced and carry more weight —> more energy

Question 21

Can fats be converted to glucose during starvation? What about glucose converted to fats?

Answer 21

No, humans don’t have the enzymes to do so. Yes, in the liver: glu = converted to FAs, which are converted to triacylglycerides