4 VP Cell Bio Lipids

Question 1

Pentose phosphate pathway (PPP)

what is it?

what are its two 2 synonyms?

it’s 2 main functions

where this pathway occurs?

why is it important?

what happens if pathway compromised?

Answer 1

an alternate cytoplasmic route for metabolism of glucose-6-phosphate (first step or intermediate of glycolysis)

hexose pathway or
hexose monophosphate shunt

2 main functions
1. produce NADPH (note: not NADH): for reductive biosynthesis of lipids

2. provision (supplying sum for use) of ribose: residues for nucleotide and nucleic acid biosynthesis (ATP, NAD+, FAD, RNA, and DNA)

pathway occurs in cytosol

its important as it produces NADPH and ribose

ribose produces: DNA and RNA

NADPH:
part of fatty acid synthesis
steroid synthesis
drug metabolism
glutathione reduction
generation of super-oxide in phagocytes by NADPH oxidase.

if pathway compromised then trouble forming rna and dna (rna needed to make proteins which are responsible for making all the biochemical rxn in body e.g. enzymes are proteins) and trouble with NADPH stuff

Question 2

PPP

is ATP consumed or generated?

PPP has high activity in?

Answer 2

no consumption or generation

1. liver and adipose tissue: biosynthesis of fatty acids from acetyl-CoA
2. Endocrine tissues: synthesis of cholesterol and steroid hormones
3. Lactating mammary gland: production of milk fats and proteins
4. Mature erythrocyte, lens and cornea: glutathione production (oxidative damage protection)

Question 3

what is a coenzyme?

Importance of NADP+/NADPH (a coenzyme) in physiological processes?

Answer 3

a non-protein compound necessary for functioning of enzyme

An important source of electrons (reducing/oxidizing agent)  Contributing to the maintenance of cellular redox homeostasis
* Reducing cytochrome P450 (drug metabolism in liver)
* Respiratory burst in phagocytic cells (NADPH-oxidase)
* Synthesis of Nitric Oxide (NO)
 relaxes smooth muscle, neurotransmitter, bactericidal activity
* Lipogenesis: Synthesis of steroids and fatty acids

Question 4

THE RESPIRATORY BURST

what is phagocytosis?

what role does NADPH play in this?

where does it occur?

4 steps of it?

Answer 4

it is a receptor-mediated ingestion of cell debris, microbial, foreign particles
they are WBC neutrophils/leucocytes

• important cell defence mechanism

NADPH is involved in production of Oxygen-containing reactive species (ROS) such as H2O2 - ROS destroy microbials

NADPH activates enzymes that produce ROS which destroy microbials

it occurs in special lysosomes (phagolysosome)

STEPS
1. chemotaxis 2. adherence 3. ingestion 4. destruction

(NADPH -> NAP+; phagocytic receptors)

Question 5

LIPIDS

what are lipids?

what are they soluble in?

components of which tissues (kingdom)?

body lipids are generally found compartmentalized because of what?
compartmentalizations?

Answer 5

lipids are mainly water insoluble (hydrophobic) water molecules

they are soluble in non-polar (non-charged) such as ether, chloroform, benzene and other lipids

they are components of plant and animal tissues

compartmentalized bc of hydrophobicity

compartmentalizations:-
membrane associated lipids

droplets of triacylglycerol in adipocytes

transported in plasma associated with proteins

Question 6

Diverse biological functions of LIPIDS:

they are a major source of what?

provide?

are which type of insulators?

they are metabolic regulators which are associated w/ ?

also imp. for controlling what?

Answer 6

• major source of energy fo the body (stored in adipocytes)
• provide:
• structural elements for biological membranes
• hydrophobic barriers -> compartmentalization
• protection against physical trauma (cushioning action)

are thermal and electrical (brain) insulators

related to liposoluble vitamins regulating enzymes (coenzyme function)

(sidenote: vitamins can activate or inactivate certain enzymes)

important for controlling body homeostasis → main component of prostaglandins and steroid hormones

Question 7

hydrophilic = lipophobic or lipophilic?
water loving polar molecule

Some lipids are Amphipathic

Answer 7

lipophobic

amphiphatic: having both hydrophilic and hydrophobic parts

Question 8

Molecules with high physiological and metabolic relevance:

Answer 8

SIMPLE structures

-Saturated and unsaturated fatty acids (SFA and UFA)
- Mono-, di- and triacylglycerol (MAG, DAG, TAG) – glycerides
(mono as in 1 fatty acid attached to glycerol)
- Neutral fats (e.g. Waxes, ceramide)

COMPLEX structures

• Phospholipids (PL)
• Glycolipids
• Lipoproteins (LP)
  *Sphingolipids/Sphingoglycolipid

DERIVED structures

• Steroids (i.e., sexual hormones)
• Eicosanoids (prostaglandins, thromboxanes, leukotrienes)
• Ketone bodies
• Fat-soluble vitamins (A,D,E,K)

Question 9

FATTY ACIDS - relevance

Fatty acids are the building blocks of ?

exist freely or not? and exist as what?

Provide energy for cells: during which period are fatty acids released from adipose tissue?
note: main storage, glycerol in adipose remember that - breaking down triacylglycerol in adipose tissue and it needs to go to liver for beta oxidation so it needs to be transported in the blood to plasma albumin)

fatty acids are transported to tissues bound to what? and why?
Beta oxidation are producers of ? In most tissues (e.g.?)

Functions?

Answer 9

Lipids

Freely and as fatty acyl esters (fatty acids with alcohol such as glycerol e.g. triacylglycerol (TAG))

Beta oxidation are producers of most energy in body e.g. liver and muscle

Provide energy for the cells: during a fast period, fatty acids are released from adipose tissue (TAG),
and transported to tissues bound to plasma albumin

Functions:
Structural component: glycoplipids, phospholipids
Hormone precursors: prostaglandins
Energy reserve/storage: TAG in white adipose tissues

Question 10

phosphate Head is hydrophillic or phobi
?

Answer 10

phillic

Question 11

Fatty acids consists of hydrocarbon chain w a terminal which group? Which ionizes at physiologic pH to what? And is what charged or not?

Anionic group (-) is hydrophillic giving the FA its what nature?

They must be associated with blood for blood plasma circulation -> mainly which protein?

What percent of FA (fatty acids) in plasma are in esterified form (TAG, PL and cholesterol esters) contained in which particles?

Answer 11

COOH to COO- and it is charged

Amphiphatic

Albumin

90% percent of FA (fatty acids) in plasma are in esterified form (TAG, PL and cholesterol esters) contained in lipoprotein particles

Question 12

saturated tail straight or kink? double bonds or nah?

Answer 12

straight and have no double bonds

Question 13

One or more double bonds = unsaturated or saturated?

Trans or cis bonds that cause a bend in position?

Addition of double bond can do what?

Answer 13

Unsaturated (think of it as double bond more bond, unsaturated more words more bonds more more)

cis= bend

Addition of double bond decreases the temp. (More fluidity between the kinked tails)

2 or more double bonds spaced at 3 Carbon intervals

Question 14

Palmitic acid 16:0
Linoleum acid: 18:2(9,12)

What do the numbers mean?

Carbon #s start with which carbon? (Hint: COO-)

Carboxyl group (COO) is attached to which # of C and what is this # of C referred to?

Carbon 3 is known as ? Carbon 4?
Carbon of the methyl group (CH3) present at v end of chain, is referred as?

arachidonic acid is also referred to as what? And why?

Answer 14

16 carbons and no double bond
18 carbons and 2 double bonds at 9th and 12th C

Carbonyl carbon (C double bond O)

1 and a-carbon

B-carbon

Gamma-carbon

Omega carbon

arachidonic acid is also referred to as Omega-6 as the first double bond is 6 carbons away from omega end

Question 15

SCFA (short chain fatty acid) - how many Cs?
MCFA
LCFA
VLCFA

Answer 15

SCFA (short chain fatty acid): 2-5
MCFA: 6-12
LCFA: 13 - 21
VLCFA: equal or greater than 22 (usually found in brain)

Question 16

Do u receive ur arachidonic acid from omega 3 or 6 oils? What does arachidonic produce?

Answer 16

6, prostaglandins and inflammatory response and eucanosoids.

Question 17

Is unsaturated man made or natural? And is it cis or trans?

Does trans (derived from cis) make it straight or kink? What is trans fat used for?

Trans fat increase good or bad cholestrol? Raise level of HDL or LDL lipoprotein?

Answer 17

Natural

Straight and used for butter, processed food

Trans fat increase bad cholestrol (LDL)

Question 18

What is the structure of lipid like?

The phosphate group can link with diff. Molecules such as ?

Phospholipids are hydrophobic or hydrophilic or amphiphatic?

What does hydrophillic head consist of?

What does hydrophobic tail contain?

Answer 18

Lipid has a polar (hydrophillic) phosphate head group and two non polar hydrophobic fatty acid tails joined by glycerol backbone.

The phosphate group can link with diff. Molecules such as serine and choline

Amphaphitic in nature

Hydrophilic head consist of glycerol that joins the fatty acids, phosphate and alcohol (serine is a polar amino acid with an alcohol function)

Hydrophobic tails contain FA (fatty acid) or FA derived hydrocarbons

Question 19

In the phospholipid bilayer/membranes, the hydrophobic parts are connected to the non polar parts of other membrane molecules such as ? ? ?

Which points outward to the aqueous environment?

Membrane phospholipids can also store what?

Nonmembrane phospholipids are imp. in “what”? And what does “what” do?

When phospholipids put in aqueous env. What happens?

Answer 19

Serine, choline and cholestrol

Hydrophillic heads point outward

They can also store intracellular messenger molecules or serve as “anchors”

Nonmembrane phospholipids are imp. In lung surfactants and detergents (bile)

When put in aqueous environment tails will get together when put in aquaous env. and hydrophillic heads turn outside

Question 20

What are the 2 Classes of phospholipids and both essential for what?

Answer 20

1. Glycerophospholipids contain “glycerol” as their backbone
   -constitute majority of PL and are prevalent in membranes
2. Sphingophospholipids contain “sphingosine” as their backbone
   - sphingosine has attached a long-chain length unsaturated fatty acid (LCFA) (-> FYI the long chain attached to it makes it hydrophobic)

• “sphingomyelin” is the main one -> is an important component of the myelin sheath of nerve fibres

Question 21

Difference between glycerophospholipids and sphingophospholipid structures?

What is glycerophospholipids make of?

What is the precursor of glycerophospholipids, esterified to diff. alcohols?

and give some examples of glycerophospholipids

Answer 21

Glycerophospholipid have 2 fatty acids attached with glycerol molecule which in turn is attached to phosphate which in turn is attached to alcohol whereas
Sphingosine is attached to 1 fatty acid and phosphate and phosphate is attached to choline

Glycerophospholipids are made of phosphatidic acid and alcohol group;

phosphaTIDIC acid is the precursor

Serine + PA -> phosphatidylserine
Ethanolamine + PA -> phosphatidylethanolamine (cephalin)

IMP! Choline + PA -> phosphotidylcholine (aka lecithin, present in lung surfactant) -

premature babies don’t have enough lunch surfactant which help in reducing surface on alveoli and avoids alveoli to collapse so have trouble breathing.
- note: choLine: L ung surfactant : L ecithin

Inositol + PA -> Phosphatidylinositol (important to regulate intracellular signaling, lipid transportation and vesicular trafficking)

• Glycerol + PA -> Phosphatidylglycerol (also present in lung surfactant)

Question 22

MORE PHOSPHOLIPIDS WITH PHYSIOLOGICAL RELEVANCE:

*** imp!!! (both) Cardiolipin: what is it a component of and maintains what?

Platelet-activating factor (PAF): what does it activate?

Which of these is part of cell membrane?

Answer 22

Cardiolipin is a component of inner mito. Membrane and relevant for maintainance of ETC complexes)

Platelet-activating factor activates inflammatory cells, platelet aggregation, involved in hypersensitivity, anaphylactic reactions

platelet-act..

Question 23

All cells except which “B” cells can synthesize phospholipids. What is “B”?

Glycerophospholipids are made from cell cytosolic precursors, there are 2 which ones?

Step A. Synthesis of phospholipids occurs in which membrane in the cell?

After step A what happens?

Answer 23

Except erythrocytes RBCs

Fatty acid coA and glycerol

Occurs in SER after which it gets modified in Golgi apparatus which them makes the membranes of organelles or will be secreted

Question 24

Phospholipid synthesis

Answer 24

1. Two fatty acids linked to coenzyme A (CoA) carriers are joined to glycerol-3-phosphate, yielding “phosphatidic” acid
2. A phosphatase then converts phosphatidic acid to diacylglycerol (glycerol + 2 fatty acids)
3. Attachment of diff. polar head groups to diacylglycerol results in formation of phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine

Question 25

Phospholipase -> ?

Where can this enzyme be found?

Answer 25

Phospholipase break down or degrade phospholipids

It can be found in all tissues and pancreatic juice, also present in many toxins and venoms such as snake and bee venoms; many pathogenic bacteria also produce these enzymes to spread infection

Question 26

Glycolipids contain 2 components what are they?

Glycoshpinglolipids contain what? Their characteristics: they don’t contain what? head function provided by? Where can you find them the most in? Where can they be located?

What are they important for???

Answer 26

Glycolipids contain both carb and lipid components

Glycoshpinglolipids contain carbohydrate and are derivates of ceramides (in which a LCFA is attached to the amino alcohol “sphingosine”)

They dont contain phosphate. Their head function is provided by mono (e.g. galactose)-oligosaccharide attached directly to the ceramide (hydrophobic tail) by an O-glycosidic bond.

Essential compounds of all membranes in the body found in highest concentration in nerve tissue

Can be located in outer parts of plasma membrane where they interact w/ extracellular environment (antigenic function - blood group);
IMP FOR REGULATION OF CELLULAR INTERACTIONS, GROWTH AND DEVELOPMENT

Question 27

ABO blood group antigens are glycosphingolipids

Sphingosine with fatty acid for O (ceramide), A and B antigen.

If neither GalNAc or Gal are present then blood group is what?

If the terminal sugar on the glycan is N-acetylgalactoseamine (GalNAc) then the blood group is ?

If the terminal sugar on the glycan is galactose (Gal) = the blood group is ?

Answer 27

O

A (galnac = 2 As)

B

Question 28

LIPIDS - Eicosanoids

Are extremely potent (having great effect) compounds that have a wide range of effects such as A and B. What are A and B?

Produced in v large or v small amounts and where?

Their biologic actions are mediated by plasma membrane ….?

are they stored and have extremely short or long half lives ?

Roles: ?

Answer 28

Physiologic (inflammatoin), pathologic (hypersensitivity)

Produced in v small amounts and act locally (Eicosanooids are considered hormone-like-lipid but instead acting like long distance like most of hormones, it acts locally)

Mediated by plasma membrane G-protein coupled receptors

They are not stored and have extremely short half lives (half life: time where half of amount of compound injected into animal is breaking down into half of that concentration)

 control of gastric integrity and renal function,
 regulation of smooth muscle contraction and blood
vessel diameter
 maintenance of platelet homeostasis  Inflammation response

Question 29

What eicosa mean? (Hint: # of carbon)

Prostaglandins (PG), thromboxanates (TX) and leukotrienes (LT) - they are required and v important in understanding what?

What are these 3 things Derived from/ immediate precursor?

3 characteristics about arachidonic acid

Answer 29

eicosa means 20

they are imp. in understanding pathophysiology of diff. things and are derived from ***omega 3 and omega 6 polyunsaturated FA with 20 carbons (eicosa = 20)

arachidonic acid is the immediate precursor

arachidonic acid:
1. **part of membrane phospholipids

2. not an essential fatty acid but can become limited (as its derived from essential FA i.e. omega 6 and 3)
3. some mammals lack or have v limited ability to make arachidonic acid

Question 30

does Prostaglandin or thromboxanates (TX) or leukotrienes (LT) regulate this?

Pain and fever response
* Action on reproductive and gastrointestinal tract
* Action on bronchopulmonary tone and vascular smooth
muscle tone (mostly vasodilation)
* Regulation of hormones, calcium movement, inflammation

does Prostaglandin or thromboxanates (TX) or leukotrienes (LT) regulate this?

• Synthesized primarily in leukocytes (macrophages, neutrophils, eosinophils and mast cells)
• Mediators of allergic response and inflammation
• Synthesis is not inhibited by NSAIDS

does Prostaglandin or thromboxanates (TX) or leukotrienes (LT) regulate this?

Synthesized primarily in platelets (thrombocytes)
* Promote platelet homeostasis (inhibition/promotion of
blood clot formation)

Answer 30

Prostaglandiin

leukotrienes

thromboxanates

Question 31

LIPIDS - cholestrol

is hydrophillic or phobic?

how many fused hydrocarbon rings does it consist of? and what is it called?

where can it be taken from? only taken from outside or can body make it?

imp. in cell membranes. y?

CHOLESTERYL ESTERS (CE)

some or most plasma cholesterol in an esterified form (with FA attached at carbon 3)?

more hydrophobic or hydrophillic that it already is?
(lipid joining to glycerol molecule)

since its hydrophobic it needs someone to travel with what is it?

are they found in membrane? yes or no
why?

Answer 31

Cholesterol
* Is a very hydrophobic compound
* Consists of four fused hydrocarbon rings (A-D) called the ‘steroid
nucleus’
* Can be taken in diet or synthesized in the body “cholesterol de novo
synthesis”
* Structural component of all cell membranes (modulating fluidity)

Cholesteryl esters (CE)
* Most plasma cholesterol is in an esterified form (with FA attached at carbon 3)
* Makes them even more hydrophobic
* For transport must be associated in a lipoprotein
* CE are not found in membranes; they are present only in low levels in association with lipoproteins

Question 32

LIPIDS - Cholesterol
Cholesterol is a sterol, a type of lipid. Performs many essential functions: list 2!

what is central in the control of the body’s cholesterol homeostasis?

Cholesterol enters liver from many sources which sources?

eliminated from the liver in the form of ? and what are they made into when they get eliminated?

Disturbances in this delicate balance can lead to?

Cholesterol is the precursor for all classes of steroid hormones such as:

Because of hydrophobicity, must be attached to ?

Answer 32

1. involved in structural component of cell membranes and lipoproteins
2. precursor of bile acid, steroid hormone and vitamin D

An appropriate supply of cholesterol is essential for the cells of the body

liver

Cholesterol enters liver from many sources (dietary, and cholesterol de novo synthesis by the liver and by extrahepatic tissues)

bile; bile salts and VLDL

can lead to deposition of cholesterol in tissues and dangerous plaque formations

glucocorticoids (cortisol); Mineralocorticoids (e.g. aldosterone); Sex hormones (e.g., estrogens, progestins and androgens)

plasma proteins, albumin

Question 33

what are the 4 diff. Plasma Lipoproteins?

their function? ( IMP! for exam)

Answer 33

Include chylomicrons, very-low-density lipoproteins (VLDL), low-density-
lipoproteins (LDL) and high-density lipoproteins (HDL)

They function to keep their component lipids soluble for transport in plasma and provide effective transport mechanism of lipids to and from tissues

Question 34

HDL, where is it generated? good or bad cholesterol? its main function?
low or high triacylglycerol?

where is VLDL generated?
low or high content of cholesterol?

LDL GENERATED FROM? func? high or low TAG?

CHYLOMICRONS generated from? high or low TAG? functions

where Abnormalities occur?

Answer 34

liver and intestine, GOOD cholestrol and its function is to deliver cholesterol from peripheral tissues to the liver for elimination (y its good)
lowest triacylglycerol (TAG) so high cholestrol

VLDL generated in liver and from triglycerides (high TAG) and has v high content of cholesterol and main function is to deliver endogenous TAG to peripheral tissues

LDL generated from VLDL; deliver cholesterol to peripheral tissues and back to liver (but if too much in peripheral then it can get stuck there); low TAG and highest cholesterol

chylomicron generated form intestine; highest TAG lowest cholesterol; dietary TAG (exogenous) to peripheral tissues

Abnormalities in lipoprotein metabolism generally occur at the site of their production or at the site of their destruction (utilization)