Lecture 5: Structure/Fctn of lipids and Lecture 6: Carbs Flashcards
Fatty acids (FA)
Produce energy, synthesis of Triglycerides (TG), PL
Triglycerides (TG)
Lipid/ fatty acid storage (unused calories)
- glycerol molecule + 3 fatty acids
- generated by esterification of fatty acids to glycerol
Phospholipids are involved in
cell membranes, cell signaling
Cholesterol
cell membranes, steroids, Vitamin D and bile acid synthesis
Bile acids
Solubilize dietary fat and oil and help with their intestinal absorption
Eicosanoids are involved in
Signaling, regulation of inflammation
Sphingolipids
Both cell signaling and cell membrane stabilization and protection against harmful chemicals
Saturated fats have
no double bond
more hydrogen atoms
more saturated- > higher melting point
Unsaturated
one double bond
Polyunsaturated
more than one double bond
Fatty acids
- occur in the body mainly as esters (attached to a glycerol) like in phospholipids or triglycerides
- usually contain even number of carbon atoms when in natural fats
cis form
120˚ is saturated and then becomes unsaturated where at the bond the angle becomes 120˚
trans form
110˚ looks like regular saturated bond
ch3ch2ch2ch2ch2ch3
Omega 3 Fatty acids
- Essential polyunsaturated fatty acids
- Present in fish oil, walnut oil, squid oil
TG effects
- High levels of TG can lead to complications such as heart diseases, stroke, obesity and metabolic syndrome (diabetes).
- Treatment diet, exercise and some lipid lowering drugs (fenofibrate)
Normal level is less than 150 mg/dL
Phospholipid
1 glycerol+ 1 phosphate group + 2 fatty acids
- amphiphilic
- play an important role in plasma membrane structure and function
Phosphatidylethanolamine is composed of:
A.glycerol and 2 fatty acids.
B. Phosphatidic acid, 2 fatty acids and a polar head group.
C.glycerol and one fatty acid and a polar head group.
D.glycerol and 3 fatty acids.
B. Phosphatidic acid, 2 fatty acids and a polar head group
Platelet activating factor (PAF)
PAF functions as a mediator of hypersensitivity, acute inflammatory reactions, and anaphylactic shock
What kind of phospholipids will increase fluidity of the plasma membrane?
A.Those that are rich in polyunsaturated fatty acids.
B.Those that are rich in saturated fatty acids.
C.Those that have a hydrophilic polar group
A.Those that are rich in polyunsaturated fatty acids.
- having multiple bonds allows for there to be space in between the molecules. This allows passage of other things in those spaces which allows fluidity
Fatty acid elongation
Fatty acid synthesis
-involves acyl-CoA and requires energy
Fatty acid Beta oxidation
Fatty acid degradation
Cholesterol
including triglycerides and phospholipids (major lipids of body)
- shuttled via lipoproteins in the body to different organs
- used to build cells and certain hormones
- involved in the synthesis of steroids, vitamins and bile acids
- too much can cause heart disease
Which enzyme for statin drugs
HMG-CoA reductase
What are Eicosanoids?
Eicosanoids are derived from arachidonic acid.
- They are involved in a number of functions regulating inflammation, immune response, cell growth, blood pressure.
- They can also cause fever and contribute to perception of pain.
Steroid example
Cortisol
- type of cholesterol
Bile acids example
Lithocholic acid
- type of cholesterol
Glucose is
stored as glycogen in liver and muscle
-important source of energy during cellular respiration
- major metabolic fuel in mammals
-
Glycogenesis
synthesis of glycogen. Involves hexokinase, phosphoglutamase
Monosaccharides
simple sugars
- most basic units of carbohydrates
formula CnH2nOn
- classified according to the number of carbons they contain in their backbone structures
Aldoses
- carbonyl group on the end
- ex: glucose (C6H12O6), ribose (C5H10O5), glucofuranose
Ketoses
- carbonyl group on the inner portion of molecule
- ex: fructose, ribulose
D-ribose
- nucleic acid and metabolic intermediate
- structural component of nucleic acids and coenzymes including ATP
D- Ribulose
- metabolic intermediate
- Intermediate in the pentose phosphate pathway
D-Xylose, D-Arabinose, D-mannose
constituent of glycoproteins
- source is plant gums
D-Glucose
- found in fruit juices, hydrolysis of starch, cane or beet sugar, maltose and lactose
- the main metabolic fuel for tissues, “blood sugar”
D-Fructose
- found in fruit juices, honey, hydrolysis of cane or beet sugar and insulin
- readily metabolized either vis glucose or directly
D-galactose
- hydrolysis of lactose
- synthesized in mammary gland for synthesis of lactose in milk
- readily metabolized to glucose
Alpha conformation
You look at the two molecules next to oxygen. R-group and OH and they should facing opposite directions
Beta conformation
You look at the two molecules next to oxygen. R-group and OH and they should facing the same directions
- beta both
Cellulose
linear structure with many monosaccharides
During glycolysis, 1 molecule of glucose produces
2 molecules of pyruvate
Glucosamine
monosaccharide that contains a nitrogen atom
Glycosylation
- major form of protein modification
- sugars are added in the golgi and ER
Glycoproteins
- contain one or more covalently linked carbohydrate chains
- cell signaling,
- plays a major role in cell recognition
- protect cell walls
- stabilize proteins against proteolysis
Sugars have
-large numbers of stereoisomers bc they contain several asymmetric carbon atoms
Hypertriglyceridemia
- Normal: Less than 150 mg/dL
- Borderline high: 150 to 199 mg/dL
- High: 200 to 499 mg/dL
- Very high: 500 mg/dL or above
Polar head groups are
hydrophilic
Apolar chaines are
hydrophobic
- tails
Plasmalogens are
Enriched in myelin sheaths and protects against reactive
oxygen species
Mutations in the ABCD1 gene lead to
impaired transport of
VLFAs to peroxisome for degradation. This leads to their accumulation in vulnerable tissues such as brain. This become toxic to myelin and result in demyelination of axons.
- The disease are called leukodystrophies
Cholesterol is involved in a number of biologically
and physiologically important function such as
- Important component of the plasma membrane.
- Regulates membrane fluidity.
- Involved in biosynthesis of steroid hormones.
- Component of lipoproteins VLDL, LDL and HDL.
Lipoproteins
• Very low density lipoproteins (VLDL)
• Low density lipoproteins (LDL)
• High density lipoproteins (HDL) shuttles lipids to the
liver for catabolism
What is good cholesterol?
HDL cholesterol
- happy cholesterol
What is bad cholesterol?
LDL cholesterol
- lousy cholesterol
HDL Cholesterol
With HDL cholesterol the higher the better
- • <40 mg/dL for men and <50 mg/dL for women = higher risk
• 40-50 mg/dL for men and 50-60 mg/dL for women = normal values
• >60 mg/dL is associated with some level of protection against heart
disease
LDL Cholesterol
With LDL cholesterol the lower the better
• <100 mg/dL = optimal values
• 100 mg/dL-129 mg/dL = optimal to near optimal
• 130 mg/dL-159 mg/dL = borderline high risk
• 160 mg/dL-189 mg/dL = high risk
• 190 mg/dL and higher = very high risk
Which of the following enzymes is targeted by statins (cholesterol lowering drugs)? A. HMG-CoA reductase. B. Acetyl-transferase. C. Fatty acyl transferase. D. Glycogen phosphorylase.
A. HMG-CoA reductase
Total Serum Cholesterol:
- <200 mg/dL = desired values
- 200–239 mg/dL = borderline to high risk
- 240 mg/dL and above = high risk
Lipids are involved in the
synthesis of steroid hormones and eicosanoids
prostaglandins leukotrienes and thromboxanes
Prostacyclin (PGI2) target
- endothelium
- kidney
- brain
Thromboxane A2 target
- platelets
- macrophages
- kidney
- smooth muscle
Prostaglandin E2 target
- brain
- kidney
- smooth muscle
Prostaglandin F2a target
- brain
- kidney
- smooth muscle
Diseases associated with carbohydrate metabolism
include
- diabetes mellitus
- galactosemia
- glycogen storage diseases
- lactose intolerance
Trioses (C3H6O3)
- Glycerose
(glyceraldehyde) - Dihydroxyacetone
Tetroses (C4H8O4)
Erythrose
Erythrulose
Pentoses (C5H10O5)
Ribose
Ribulose
Hexoses (C6H12O6)
Glucose
Fructose
Glucose is: A. an ester B. a ketose C.an aldose D. an ether
C.an aldose
- has an aldehyde group on carbon 1
L-Xylulose
- Metabolic intermediate
-Excreted in the urine in
essential pentosuria
D-glucose and D-Fructose can exist in
alpha and beta conformation
Glucosamine is a naturally occurring amino sugar with the following structure. In humans it is the precursor for glycosaminoglycans, glycolipids and glycoproteins What is its configuration? A. Alpha-D B. Alpha-L C.Beta-D D.Beta-L
A. Alpha-D
Starch molecule looks like
- polysaccharide
- simplest form is amylose: looped form
- amylopectin is the branched form: branches out
Glycogen molecule looks like
- polysaccharide compose of alot more subunits than starch
- branches out
- less ordered
Cellulose (fiber) looks like
- polysaccharide
- very order structure
Glucose is stored as
glycogen in liver and muscle
Glycogenesis
synthesis of glycogen
Glycogenolysis
degradation of glycogen
1 Acetyl-CoA yields
1 ATP, 3 NADH and 1 FADH2
1 NADH yields
2.5 ATP
1 FADH2 yields
1.5 ATP
During glycolysis, 1 molecule of glucose produces. A. 1 molecule of pyruvate B. 2 molecules of pyruvate C. 3 molecules of pyruvate
B. 2 molecules of pyruvate
Glucosamine
monosaccharides that contain a nitrogen atom
Monosaccharides with amine groups are found
mainly in
the carbohydrate chains of glycoproteins
All N-linked carbohydrates are linked through
N-Acetylglucosamine and the side chain of Asparagine
Most O-linked carbohydrate covalent attachments to proteins involve a linkage between
the monosaccharide N- Acetylgalactosamine and the
side chain of a serine or threonine residue
