Lecture 12 - Lipids and lipid membranes

Question 1

what does lipid refer to?

Answer 1

-a large heterogeneous group of fat soluble biological compounds

Question 2

what compounds are considered lipids? (7)

Answer 2

1. fatty acids
2. triglycerols
3. glycerophospholipids
4. sphingolipids
5. steroids
6. isoprenoids (terpenoids)
7. eicosanoids

Question 3

what are 4 major functions of lipids?

Answer 3

1. membranes
2. energy storage
3. signaling (as hormones)
4. vitamins

Question 4

what are fatty acids?

Answer 4

-carboxylic acids with long hydrocarbon tail?

Question 5

what are the most common types of fatty acids?

Answer 5

C16 or C18 fatty acids

Question 6

what are saturated carbon bonds?

Answer 6

single C-C bonds

Question 7

what are partially unsaturated?

Answer 7

some C=C double bonds

Question 8

double C=C bonds on fatty acid tails are always ____

Answer 8

cis

Question 9

where does the first C=C bond often start for unsaturated fatty acids?

Answer 9

C9

Question 10

if there is more than one C=C bond, how often do they usually repeat?

Answer 10

-every 3 carbons

C9, C12, C15 etc.

Question 11

what do cis double bonds create?

Answer 11

rigid kinks in the fatty acid tail

Question 12

what are triglycerols?

Answer 12

esters made from attaching fatty acids to a glycerol

Question 13

what are examples of triglycerols?

Answer 13

• fats and oils in plants and animals

- usually complex mixtures

Question 14

what do animals use triglycerols for?

Answer 14

-long-term energy storage

Question 15

where is fat deposited in?

Answer 15

fat cells in side adipose tissues, mostly subcutaneous

Question 16

what is a function of glucose?

Answer 16

-glucose stored in the form of glycogens can release energy rapidly

Question 17

what is characteristic of glycogens and energy storage?

Answer 17

• lower density

- highly hydrated and more oxidized

Question 18

do fats contain O?

Answer 18

• anhydrous

- contain almost no O

Question 19

-typical fat content of humans allow them to survive starvation for ______

Answer 19

2-3 months

Question 20

how are glycerophospholipids obtained?

Answer 20

-by replacing a fatty acid branch in triglycerol by a PO4-linked polar head group

Question 21

what can cleave glycerophospholipids be cleaved by?

Answer 21

various phospholipase enzymes

Question 22

what are the hydrolysis products of cleaved phospholipids used as? why?

Answer 22

• signal transducers

- they are fat-soluble but easily distinguishable from membrane lipids

Question 23

what are plasmalogens?

Answer 23

• variation of a glycerophospholipid

- one of the ester is modified to an ether with an alpha C=C bond

Question 24

plasmalogens are easily ______

Answer 24

oxidized

Question 25

why are plasmalogens easily oxidized?

Answer 25

-thought to act as oxygen free radical scavengers

Question 26

what is the parent of a sphingolipid?

Answer 26

sphingosine?

Question 27

what is a sphingosine?

Answer 27

-a glycerol modified by one amine substitution on C2 and a hydrocarbon chain on C3 instead of an H through a C=C bond

Question 28

what is a sphingomyelin?

Answer 28

-key component of electrically-insulating myelin sheath around nerve cells

Question 29

what is a sphingolipid?

Answer 29

- glycerophospholipd modified by an amide (instead of an ester) linkate to one of the fatty acids - OH on C1 - C=C double bond for other fatty acid

Question 30

what are gangliosides and cerebrosides classified as?

Answer 30

sphingolpids

Question 31

what are 4 functions of gangliosides?

Answer 31

1. hormone binding sites 2. cell recognition determinants 3. cell signaling mediators 4. receptors for small proteins

Question 32

gangliosides are usually ____ on the cell surface

Answer 32

exposed

Question 33

cerebrosides have only ______ linked to the ceramide

Answer 33

one sugar

Question 34

what is the structure of a steroid?

Answer 34

-4-fused ring

Question 35

what is cholesterol?

Answer 35

a cell membrane additive

Question 36

what is cholesteryl stearate?

Answer 36

esterified by a fatty acid

Question 37

what do many steroids act as?

Answer 37

hormones

Question 38

what is the function of cortisol?

Answer 38

reduce inflammatory reactions

Question 39

what is the function of aldosterone?

Answer 39

-regulates the excretio nf salt + water from the kidney

Question 40

what is the function of testosterone + estradiol?

Answer 40

affects sexual development

Question 41

What is vitamin D?

Answer 41

Ca2+ regulatio steroid hormone

Question 42

what does vitamin D do?

Answer 42

- promotes intestinal absorption of Ca2+ from dietary calcium - increase calcium deposition into teeth + bone structures

Question 43

what is the signature of an isoprenoid?

Answer 43

C-C single and double bond structure

Question 44

where are isoprenoids found?

Answer 44

- plants - fungus - bacteria

Question 45

what are the functions of isoprenoids?

Answer 45

- signaling molecules (pheromones) - pigments - for defense (toxins)

Question 46

What is coenzyenzyme Q (coQ)/ubiquinone used for?

Answer 46

electron transport

Question 47

what is retinoic acid used for?

Answer 47

vision | -tissue repair

Question 48

what is vitamin E

Answer 48

an antioxidant | formed from beta carotene

Question 49

what are the functions of phylloquinone/menaquinone?

Answer 49

blood clotting

Question 50

where are Eicosanoids derived from?

Answer 50

-arachidonic acid

Question 51

what do eicosanoids do?

Answer 51

fever + pain - regulate blood pressure - blood coagulation - reproduction

Question 52

what are most lipids in the cell used for?

Answer 52

-form the plasma membrane or membranes separating cell compartments

Question 53

what are major components of the cell membrane?

Answer 53

-amphiphilic phospholipid molecules

Question 54

what do phospholipids form?

Answer 54

bilayers with small curvature

Question 55

what do phospholipids spontaneously form?

Answer 55

liposomes

Question 56

how are bilayers ordered?

Answer 56

they are inherently disordered

Question 57

the ordering of the phospholipids are _____ dependent

Answer 57

temperature

Question 58

how do phospholipids form function membranes?

Answer 58

they must stay above the ordering transition temperature

Question 59

what happens to lipid bilayers below the transition temperature?

Answer 59

- stuck in a solid-like state | - lacks the fluidity needed for membranes to function properly