intro to lipids (10)

Question 1

carbons in TGs vs carbons in carbs, which ones have a lower oxidation state?

Answer 1

the carbons in triglycerides

Question 2

how many kcal/gram in carbs?

Answer 2

4 kcal/g

Question 3

how many kcal/gram in protein?

Answer 3

4 kcal/g

Question 4

how many kcal/gram in fat?

Answer 4

9 kcal/g

Question 5

how many kcal/gram in alcohol?

Answer 5

7 kcal/g

Question 6

why do carbohydrates have twice the dry weight as TGs?

Answer 6

because TGs are stored in an anhydrous state whereas cabs are bound to water

Question 7

describe the double bonds in polyunsaturated fatty acids

Answer 7

the bonds are neither adjacent nor conjugated
this allows the structure to not be as easily oxidized
also the double bonds are almost always separated by a methyl group

Question 8

why type of fatty acid is the following describing?

“ highly flexible, energetically favorable”

Answer 8

saturated fatty acids

Question 9

which will have a lower melting temperature?

a TG with side chains containing double bonds or without double bonds

Answer 9

a TG with double bonds with have a lower melting point (their double bonds interfere with packing)

Question 10

what is the common name for C14?

Answer 10

myristic

Question 11

what is the common name for C16 with no double bonds?

Answer 11

palmitic

Question 12

what is the common name for C16 with 1 double bond?

Answer 12

palmitoleic

Question 13

what is the common name for C18 with no double bonds?

Answer 13

stearic

Question 14

what is the common name for C18 with 1 double bond?

Answer 14

oleic

Question 15

what is the common name for C18 with 2 double bonds?

Answer 15

linoleic

Question 16

what is the common name for C18 with 3 double bonds?

Answer 16

linolenic

Question 17

what is the common name for C20 with 4 double bonds?

Answer 17

arachidonic

Question 18

list the 3 components of bile

Answer 18

bile acids
phosphatidyl choline
cholesterol

Question 19

what is required for pancreatic lipase activation?

Answer 19

requires the formation of a complex with colipase & a droplet of emulsified lipid which will stabilize the “open” confirmation and allow access to substrate while shielding against bile salts (which would inactivate the enzyme)

Question 20

where are most TGs hydrolyzed? what enzyme does this?

Answer 20

pancreatic lipase in the duodenum and proximal jejunum

Question 21

what is colipase?

Answer 21

a protein that is secreted as the an inactive precursor by the pancrease and activated in the duodenum by trypsin. it is necessary for lipase to have access to lipid substrates

Question 22

what are the two main products after TG has been hydrolyzed by pancreatic lipase?

Answer 22

2-MAG

NEFA

Question 23

what is the major FA transporter in enterocytes?

Answer 23

FATP5 from the fatty acid transport protein family

Question 24

what aquaporin mediates glycerol transport?

Answer 24

AQP3

Question 25

list the 3 main causes of steatorrhea

Answer 25

1. failure of bile production of blockage of bile flow 2. exocrine pancrease dysfunction or obstruction of pancreatic duct 3. failure of uptake into intestinal mucosal cells

Question 26

for long chain fatty acids, answer the following: requires pancreatic lipase? requires micelle formation? present in feces?

Answer 26

requires pancreatic lipase? yes requires micelle formation? yes present in feces? minimal

Question 27

for medium chain fatty acids, answer the following: requires pancreatic lipase? requires micelle formation? present in feces?

Answer 27

requires pancreatic lipase? no requires micelle formation? no present in feces? no

Question 28

for short chain fatty acids, answer the following: requires pancreatic lipase? requires micelle formation? present in feces?

Answer 28

requires pancreatic lipase? no requires micelle formation? no present in feces? substantial

Question 29

where is the primary site of absorption for: LCFA MCFA SCFA

Answer 29

LCFA: small intestine MCFA: small intestine SCFA: colon

Question 30

what is the origin for the following: LCFA MCFA SCFA

Answer 30

LCFA: in the diet as TGs MCFA: in the diet as TGs SCFA: bacterial conversion of nonabsorbed CHO

Question 31

what is the requirement for TGs to be able to be transported through the lymph and blood?

Answer 31

they must be packaged into a lipoprotein particle: chylomicrons

Question 32

what is the name of the principal protein component of nascent chylomicrons as they are produced in the intestinal mucosa?

Answer 32

Apo-B48

Question 33

what does the metabolism of lipoproteins depend on?

Answer 33

upon molecular recognition between various enzymes (or receptors) and the apoproteins on the surfaces of the various lipoprotein particles