4 VP Cell Bio Lipids Flashcards
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?
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
- 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
PPP
is ATP consumed or generated?
PPP has high activity in?
no consumption or generation
- liver and adipose tissue: biosynthesis of fatty acids from acetyl-CoA
- Endocrine tissues: synthesis of cholesterol and steroid hormones
- Lactating mammary gland: production of milk fats and proteins
- Mature erythrocyte, lens and cornea: glutathione production (oxidative damage protection)
what is a coenzyme?
Importance of NADP+/NADPH (a coenzyme) in physiological processes?
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
THE RESPIRATORY BURST
what is phagocytosis?
what role does NADPH play in this?
where does it occur?
4 steps of it?
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)
LIPIDS
what are lipids?
what are they soluble in?
components of which tissues (kingdom)?
body lipids are generally found compartmentalized because of what?
compartmentalizations?
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
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?
- 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
hydrophilic = lipophobic or lipophilic?
water loving polar molecule
Some lipids are Amphipathic
lipophobic
amphiphatic: having both hydrophilic and hydrophobic parts
Molecules with high physiological and metabolic relevance:
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)
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?
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
phosphate Head is hydrophillic or phobi
?
phillic
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?
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
saturated tail straight or kink? double bonds or nah?
straight and have no double bonds
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?
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
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?
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
SCFA (short chain fatty acid) - how many Cs?
MCFA
LCFA
VLCFA
SCFA (short chain fatty acid): 2-5
MCFA: 6-12
LCFA: 13 - 21
VLCFA: equal or greater than 22 (usually found in brain)
Do u receive ur arachidonic acid from omega 3 or 6 oils? What does arachidonic produce?
6, prostaglandins and inflammatory response and eucanosoids.
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?
Natural
Straight and used for butter, processed food
Trans fat increase bad cholestrol (LDL)
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?
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
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?
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
What are the 2 Classes of phospholipids and both essential for what?
- Glycerophospholipids contain “glycerol” as their backbone
-constitute majority of PL and are prevalent in membranes - 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
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
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)
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?
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..
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?
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
Phospholipid synthesis
- Two fatty acids linked to coenzyme A (CoA) carriers are joined to glycerol-3-phosphate, yielding “phosphatidic” acid
- A phosphatase then converts phosphatidic acid to diacylglycerol (glycerol + 2 fatty acids)
- Attachment of diff. polar head groups to diacylglycerol results in formation of phosphatidylcholine, phosphatidylethanolamine, phosphatidylserine
