1.11.structure and function of lipids

Question 1

Name the different forms which lipids exist in the human body

1. structures
2. substrates
3. reservoirs
4. hormones
5. antioxidants

Answer 1

1. lipids can be
   
   1. structural
      
      1. plasma membrane
   2. substrates
      
      1. for enery- fatty acid degredatio->AcetylCoA degradation-> ATP
   3. reservoirs of signaling molecules- storedsomewhere
      
      1. Eicosanoids
         
         1. leukotrines
         2. prostaglandins
         3. prostacyclin
         4. thromboxanes
      2. arachadonic acid-
         
         1. fatty acid, in the membrane, can be an antioxidant, but most importantly isa precursor for all the
   4. hormones
      
      1. steroids
      2. protein
         
         1. insulin
         2. glucagon
   5. antioxidants- any fat that has a double bond
      
      1. beta-carotene
      2. unsaturated fats
         
         1. the double bonds acts as a free radical acceptor

Question 2

List an important eicosanoid precursor and its three big products

Answer 2

Arachidonic acid

1. leukotrienes
2. prostaglandins
3. thromboxanes

Question 3

describe the fats in the outer most layer of a cell

Answer 3

structural lipids

1. lipid bilayer
   
   1. phospholipids
   2. sphingolipids
      
      1. specialized fatty acid
   3. cholesterol
2. only way to control what goes in and what leaves

Question 4

define the phospholipids

1. units of composistion
2. Define the 5 modified polar groups after esterfication with phosphoric acid moiety.

Answer 4

phospholipid

1. units of composition
   
   1. glycerol
   2. fatty acids
   3. phophsphoric acid (H3PO4; bound by C3)
   4. a polar head examples
      
      1. choline
      2. serine
      3. ethanolamine
      4. inositol
      5. glycerol
2. esterfied phospholipid forms a polar end
   
   1. combination of phosphoric acid and alcohol compound
      
      1. choline->lecithins (phosphatitylcholine)
         
         1. used to make phophatidylchline
            
            1. commonly called (lecithins)
         2. sphingomyelin ratio is used in assinging the lung maturity of a fetus in order to determine the optimum time for elective termination of pregnency
      2. ethanolamine->phosphatidylethanolamine
         
         1. found in the inner most leaflet of a Plamalogen
      3. serine->phophatidylserine
         
         1. found in the inner leaflet of the membrane
      4. inositol->phosphatidyl inositol
         
         1. key membrane constituent
      5. glycerol->phosphatidylglycerol
         
         1. a major component of pulmonary surfactant

Question 5

what is an esterfication process

Answer 5

acid +alcohol

Question 6

a woman wants to know what test she can take to refine her delivery date, for her child.

what test would validate this , why

Answer 6

measuring lecithin

1. lecithin:shpingomyelin ratio
   
   1. this is aused to asses the lung maturity of a fetus in order to determine the optimum time for an elective termination of pregnancy

Question 7

a child comes in with the following

1. see photo
2. characteristics
3. systemic shortening of the proximal bones, seizures, recurrent RTI,

what is the disease and its cause? what is the role of this missing agent?

Answer 7

phosphatidylethanolamine

1. location
   
   1. inner leaflet of plasmalogin
2. plasmalogin
   
   1. function
      
      1. play role in
         
         1. anti-oxidation
         2. signal transduction
         3. membrane structure
   2. diseae
      
      1. abnormality in plamalogens biosynthesis in peroxisomes leads to rhizomelic chondroplasia Punctata
         
         1. rare developmental brain disorder
         2. character
            
            1. systemic shortening of the proximal bones, seizures, recurrent RTI,

Question 8

A doctor orders a test to asses the level of planned cell death in the body, what is this test? describe it constiuent it measures

Answer 8

annexin V assay

1. measures phosphatidyl serine
   
   1. location
      
      1. inner leaflet of the membrane
   2. function
      
      1. crutial role in apoptosis

Question 9

activation of G(q,a) leads to stimulation of important lipid moeitey in the membrane, explain.

Answer 9

phosphatidylinositol

1. key secondary messenger
   
   1. IP3= inositol triphosphate, used to transduce signal in Gq,a subunit stimulation
2. location
   
   1. key membrane contituent

Question 10

Which component was noted to be invaliable in the developing lungs shortly after birth?

Answer 10

Phosphatidylglycerol

1. location
   
   1. major component of pulmonary surfactant
2. testing
   
   1. used to asses the fetal lung development
   2. w/o proper mixture of proteins/fats, the lungs can stick together, inhibiting proper gas exchange

Question 11

Answer 11

Question 12

describe the structure of the following

1. glycerophospholipid
2. plasmalogen
3. glycerolipid
4. sphingomyelin

Answer 12

Question 13

define the following about lipids

1. location
   
   1. membranes
   2. blood
   3. storage
2. source
3. chracteristic

Answer 13

1. location
   
   1. membranes
      
      1. esterfied to glycerol as phopholipids
   2. blood stream
      
      1. packaged in lipoproteins
      2. linked albumin
   3. storage as adipose
      
      1. adipose esterfied to glycerl forming triglycerides for storage
2. provided from
   
   1. diet
   2. synthesis from excess glucose
      
      1. essenttial fatty acids can only be provided by diet
         
         1. ALA, EPA, DHA
3. characteristics
   
   1. hydrophobic
   2. solidity and rigidity depends on the saturation
      
      1. increse saturation= rigid

Question 14

summarize the end products for glucose

Answer 14

glucose

1. end products
   
   1. oxidation
      
      1. CO2 + H2O
   2. storage
      
      1. Triacylglycerol
   3. synthesis
      
      1. phopholipis
      2. sphingolipids

Question 15

discuss the differenc between saturated/unsaturated fatty acids

1. structure
2. fluidity/movement

Answer 15

1. saturated
   
   1. structure
      
      1. hydrophobic interactions
      2. rigid structure
      3. tightly packed
   2. fluidity/movment
      
      1. impede membrane protein
      2. interfere with ion transport
         
         1. important for inner layer of mito
      3. decrease membrane fluidity
      4. increases melting point
2. unsaturated
   
   1. structure
      
      1. have one or several unconjugated double bonds in cis configuration
      2. cis-oleic acid
   2. fluidity/movment
      
      1. increased fluidity
      2. facilitation of transport
      3. lowers melting point

Question 16

describe triglycerol metabolism

1. fed state
2. fasting state

Answer 16

Question 17

define the following for cholesterol

1. 2 main locations location
2. 2 sites of origin
3. precursor to which three molecules

Answer 17

cholesterol

1. location
   
   1. present in the plasma membrane
      
      1. forms
         
         1. free form
         2. esterfied with an FA of a phospholipid
   2. bloodstream
      
      1. carried mainly in
         
         1. LDL
         2. HDL
2. origin
   
   1. diet
   2. liver synthesizes from A-CoA
3. precursor
   
   1. steroid hormones
   2. bile salts
   3. vitamin D

Question 18

summarizes the products from A-CoA

Answer 18

A-CoA

1. cholesterol
   
   1. membranes
   2. bile salts
   3. steroid hormones
   4. Vitamin D

Question 19

sphingolipids are imperative to many cellular/tissue operations. describe the following

1. function
2. structure
3. synthesis
4. disease manifestation

Answer 19

1. function
   
   1. intercellular communication
   2. antigenic determination
      
      1. ABO
   3. can be receptors for viruses and bacteria toxins
2. structure
   
   1. sphingosine back bone
3. synthesis of sphingomyelin
   
   1. sphingosine + another FA= ceramide
      
      1. ceramide + phosphatidylcholine =sphingomyelin
         
         1. ​important componet of axon sheath
4. disease
   
   1. shingolipidosis
      
      1. lysosomal storage disease- cannot degare sphingolipids

Question 20

Answer 20

Question 21

adipose tissue has two important secretions. define the following

1. secretion
   
   1. why
   2. action

Answer 21

adipose tissue is an active endocrine organ secreting substances that play a role i mtabolism of both: glucose and fat

1. Leptin
   
   1. why
      
      1. secreted when triglyceride levels increase
   2. action
      
      1. stimulates hypothalamus
         
         1. leads to cessation (anorexigenic factors)
      2. on adiponectin
         
         1. leads to the uptake of glucose by peripheral tissues
2. adiponectin-most abundantly secreted of the two
   
   1. why
      
      1. assist body with gluconeogenesis and uptake of glucose from blood stream
   2. action
      
      1. binds to receptors - initiating transduction cascade in
         
         1. AdipoR1 and AdipoR2
            
            1. cascades
               
               1. AMPK and PPARa
         2. location- both pathways lead to
            
            1. muscles
               
               1. enhace
                  
                  1. FAO
                  2. Glu-uptake
            2. liver
               
               1. FAO

Question 22

A chemical was used on obese patients to loose weight and had no effect, but people deficient in this chemical it did lead to weight loss. Define the substance and describe the situation.

Answer 22

leptin

1. obese
   
   1. adminstering leptin to obese patients does not lead to weight loss
   2. leptin resistance condition inf obese patients due to receptor desenitization
2. defficient
   
   1. individuals who do not make enough leptin see tremendous results

Question 23

describe the steps of dietary fat absorption and organ exposure. include order of organs and

Answer 23

1. dietary fat is ingested
2. bound in chylomicrons in the gut cell
3. travel in the lymph
4. go to in order
   
   1. muscle
      
      1. skeletal muscle
      2. cardiac muscle
   2. adipose for storage
   3. reminant go to the liver
      
      1. gets what ever is left over and the chylomicron and degrades both

Question 24

why is it important to manage the %age of saturated lipids just a little over 50%

Answer 24

less double bonds=morerigid

if all of them are saturated, then there will be very little movement.

Question 25

What effect does a adipocyte have on blood sugar/fats? what happens when its size decrease by 50%?

Answer 25

Adiponectin is secreted from adipocytes to decrease the blood levels of: glucose/free fatty acids

1. decreasing the size of the fatty acids= reduction of adiponectin
   
   1. results
      
      1. accumulation in blood stream
      2. thought to be cause of insulin resistance in obesity
   2. treatment
      
      1. activate the pathway from another spot to manage the high levels of fatty acids and glucose
         
         1. drugs that stimulate the PPARa lead to the
            
            1. fatty acid transport
            2. energy uncoupling
            3. FAO

Question 26

what is used to measure the determine fetal lung maturity and dvelopment

Answer 26

phosphatidylcholine:sphingomyelin ratio=lung maturity.

phosphotidylglycerol=lung development. imperative for surfactant to work right

Question 27

what are the two structures that package fatty acids? why?

Answer 27

Fatty acids are packaged in

1. albumin
2. lipoproteins
   
   1. LDL
   2. chylomicrons

Fatty acids are packaged before they go into the blood, because of the insolubility of fats in blood

Question 28

explain why LDL=good and HDL=bad

Answer 28

LDL is taken to the tissue/cells that need the energy

HDL oozes from tissues and communicates with liver to say stop FAO

1. higher HDL means that the body has more fat stored than needed.

Question 30

What is measured to assess fetal lung development?

Answer 30

phosphatidylglycerol

1. a major componenet of pulmonary surfactant
2. used to ass teh fetal lung development

Question 31

adiponectin

1. functino-2
2. action
   
   1. two primary locations

Answer 31

1. adiponectin is recognized as a
   
   1. key regulator of insulin sensitivity
   2. regulator in tissue inflammation
2. action on
   
   1. skeltal muscle - Adipo R1
      
      1. prominent action to activate AMPK
         
         1. promotes oxidation of lipids
            
            1. fatty acids are broken down two carbons at a time for ATP
   2. liver - AdipoR2
      
      1. enhances insulin sensitivity and reducses steatosis via AMPK and increased PPARa(peroxison proliferator activated receptor alph ligand)