lipids

Question 1

lipid functions

Answer 1

1. store energy in adipose cells
2. phospholipids constitute a barrier between intracellular and extracellular environments
3. cholesterol serves as building block for hydrophobic steroid hormones

Question 2

cardinal characteristic of the lipid

Answer 2

hydrophobicity

Question 3

fatty acid structure

Answer 3

composed of long unsubstituted alkanes that end in a carboxylic acid

Question 4

solvation shell function

Answer 4

allows for most water-water interaction and least water-lipid interaction

Question 5

triacylglycerol structure and function

Answer 5

composed of three fatty acids esterified to a glycerol molecule, stores fatty acids in form of fat, amphipathic

Question 6

lipases

Answer 6

enzymes that hydrolyze fats

Question 7

why are fats efficient storage molecules?

Answer 7

they pack more closely than carbohydrates, and they store more energy due to being more reduced

Question 8

lipid bilayer

Answer 8

formed by hydrophobic interactions

Question 9

what affects membrane fluidity?

Answer 9

double bonds tend to increase membrane fluidity and decreasing the length of fatty acid tails also increases fluidity.

Cholesterol will increase fluidity in low temps and decrease it in high temps

Question 10

how do peptides exert their effect on a cell?

Answer 10

protein receptors in the cell membrane bind these hormones and transmit a signal into the cell in a second messenger cascade.

Question 11

isoprene unit

Answer 11

C5H8

Question 12

cholesterol function

Answer 12

obtained from the diet and synthesized in the liver, carried in the blood packaged with fats and proteins into lipoproteins

make testosterone and estradiol

Question 13

steroid characteristic

Answer 13

highly hydrophobic so they can diffuse right through the lipid bilayer membrane into the cytoplasm, receptors are located within cells

Question 14

sphingolipids

Answer 14

backbone is sphingosine, example in humans is sphingomyelin, an important component of the myelin sheath around neurons

Question 15

waxes

Answer 15

long chain fats esterified to long chain alcohols,

extremely hydrophobic

Question 16

fat soluble vitamins

Answer 16

absorbed with dietary fat and stored in adipose tissue and in the liver

Question 17

prostaglandins

Answer 17

derived from 20 carbon fatty acids, have vastly different roles in different tissues, depending on the receptor to which they bind

Question 18

fatty acid oxidation first part

Answer 18

triacylglycerol is hydrolyzed to liberate free fatty acids which can then undergo B-oxidation.

catalyzed by acyl-CoA synthetase, requires two ATP equivalents to generate a fatty acyl-CoA, which is then transported into the mitochondrion

Question 19

oxidation of unsaturated fatty acids

Answer 19

requires additional steps, isomerase required to move double bond and reductase required if several double bonds are present

Question 20

ketogenesis

Answer 20

ketone bodies generated by liver from acetyl CoA, which are then converted back to acetyl CoA once reaching the target to enter the Krebs Cycle

occurs when blood glucose falls significantly and glycogen stores become exhausted during periods of starvation

Question 21

fatty acid synthesis

Answer 21

takes place in cytoplasm, involves addition of two carbon units from a fatty acid chain

Question 22

committed step of fatty acid synthesis

Answer 22

synthesis of malonyl-CoA from acetyl CoA, facilitated by acetyl-CoA carboxylase

Question 23

fatty acid synthase function

Answer 23

an enzyme with multiple catalytic domains, aids fatty acid synthesis
binds acetyl CoA and malonyl CoA.

After Malonyl CoA is decarboxylated, the ACP domain undergoes two reductions using NADPH.

This process repeats

Question 24

order of metabolism

Answer 24

cells prefer carbohydrates as fuel, which is used when blood sugar is high.

Question 25

fatty oxidation of fatty acyl-CoA in mitochondria

Answer 25

fatty acyl-CoA undergoes a repeated series of four reactions, which cleave the bond between alpha and beta carbon to liberate an acetyl-CoA in addition to generating one FADH2 and one NADH

Each round of B-oxidation cleaves a two carbon acetyl-CoA from the molecule, and the final round cleaves a four carbon fatty-acyl CoA to generate two acetyl CoA