Digestion n lip Bio Flashcards
Main dietary carbs their components and linkages
Starch:amylose-straight chain.alpha 1-4
Amylopectin:branched but less branches then glycogen,alpha 1-4 and alpha 1-6
Sucrose-alpha beta 1-2
Lactose-beta 1-4
In mouth which enzyme acts on carbs,what’s the major product that enters stomach
In the mouth, salivary alpha-amylase cleaves starch by breaking a-1,4 linkages between glucose residues within the chains
- Dextrins (linear and branched oligosaccharides) are the major products that enter the stomach.
How ph of acidic carbs is changed in intestine
It releases bicarbonate (HCO3À) secreted by the pancreas neutralizes the stomach acid, raising the pH into the optimal range for the action of the intestinal enzymes.
Which enzyme works in intestine to break carbs ,which bonds it breaks and what are it’s products
The pancreas secretes an alpha -amylase that acts in the lumen of the small intestine and, like salivary amylase, cleaves a-1,4 linkages between glucose residues.
The products of pancreatic a-amylase are the disaccharides maltose and isomaltase, trisaccharides, and small oligosaccharides containing a-1,4 and a-1,6 linkages.
In pancreatitis patients serum level of which enzymes disturb.. and their level î or !
Amylase and lipase levels î
Enzymes released by brusg borders of intestinal cells and what do they do
Isomaltase- cleaves a-1,6 linkages, releasing glucose residues from branched oligosaccharides.
Glucoamylase-breaks alpha 1-4 linkages of oligosachharides
Sucrase converts sucrose to glucose and fructose.
Lactase (a b-galactosidase) converts lactose to glucose and galactose.
Bloating, abdominal cramps, and watery diarrhea result due to
Lactase deficiency occurs in more than 80% of Native, African, and Asian Americans. Lactose is not digested at a normal rate and accumulates in the gut, where it is metabolized by bacteria. Bloating, abdominal cramps, and watery diarrhea result.
Carb that’s not digestible and why
enzymes produced by human cells cannot cleave the b-1,4 bonds of cellulose, this polysaccharide is indigestible.and is a part of deitary fiber
What happen to TAGs in intestine..which substances are released by gall bladder and pancreas…… bile salts are resorbed in
(Gall bladder release bile salts to emulsify lipids.pancreas release hco3-,pancreatic lipase, colipase)….
(TAGs are converted by pancreatic lipase with aid of colipase into 2-monoacyl glycerols and free fatty acids…. which convert into micelle(microdroplets of fats+cholestrol+bile salts+fat soluble vitamins).. which are then absorbed by microvilli)
……. (bile salts are resorbed in the terminal ileum
What’s the anti-obesity drug and what it does
The antiobesity drug, orlistat, inhibits pancreatic and gastric lipase, resulting in about 30% blockage of dietary fat from digestion and absorption, leading to reduction in body weight in some patients.
Synthesis of chylomicrons
Fatty acids absorbed in epithelial cells of intestine are activated into fatty acyl CoA by enzyme fatty acyl Co-A synthetase . Fatty acyl Co-A combines with 2-monoacylglycerol to from diacylglycerol which combines with another fatty acid to from triglyceride.TAGs are passed into lymph packaged in new chylomicrons which then enter in blood
Which substances convert the following zymogen forms of carbs into active forms
1) Pepsinogen
2) Trypsinogen
3) Chymotrypsinogen
4) Proelastase
5) Procarboxypeptidases
1) H+
2) enteropeptidase
3) Trypsin
4) trypsin
5) trypsin
Write the specificity of different peptidases
Pepsin but tends to cleave peptide bonds in which the carboxyl group is contributed by the acidic amino acids, aromatic amino acids, or leucine.
Trypsin cleaves peptide bonds in which the carboxyl group is contributed by arginine or lysine……… Chymotrypsin usually cleaves peptide bonds at the carboxyl group of aromatic amino acids or leucine……….. Elastase cleaves at the carboxyl end of amino acid residues with small, uncharged side chains such as alanine, glycine, or serine…….. Carboxypeptidase A cleaves aromatic amino acids from the C terminus…… Carboxypeptidase B cleaves the basic amino acids, lysine and arginine, from the C terminus.
Examples of endopeptidases and exopeptidases
Endopeptidases—1)trypsin 2)chymotrypsin 3)elastase
Exopeptidases—1)carboxypeptidase A
2)carboxypeptidaseB
Transport of amino acids into bloodstream
The major transport system involves cellular uptake by the cell of a sodium ion and an amino acid by the same carrier protein on the luminal surface.
b. The sodium ion is pumped out of the cell into the blood by the Na+ -K + ATPase, whereas the amino acid travels down its concentration gradient into the blood.
c. Thus, amino acid transport from the intestinal lumen to the blood is driven by hydrolysis of adenosine triphosphate (ATP) (secondary active transport).
Bicarbonate is released by ___in response to ____,failure to neutralise the acidic contents result in____
Bicarbonate is released from the pancreas in response to the hormone secretin, which is synthesized by the cells lining the duodenum. Failure to fully neutralize the acidic gastric contents results in peptic ulcers in the duodenum.
What happens in cyctinuria
transport of cysteine and basic amino acids is defective in both the intestine and kidney. Cysteine cannot be resorbed from the glomerular filtrate and concentrates in the urine. Within the urine, the cysteine is oxidized to cystine, which can crystallize, forming kidney stones.
Hartnups disease
In Hartnup disease, transport of neutral amino acids is defective, resulting in potential deficiencies of essential amino acids because they are not absorbed
from the diet.
a) Fatty acids(min., max and order of Carbon atoms,)
b) Examples of saturated fatty acids 2)mono-unsaturated FAs
3) poly-unsaturated FAs
a) min=2 Cs,max=24 Cs,even no. in animales
b) butyric acid,arachidic acid,stearic acid
2) oleic acid(found in all fats almost)
3) linoleic acid(2 double bonds) linolenic acid(3DBs) arachidonic acid(4DBs)**
Essential fatty acids and their lack causes
Those which can’t be made in body.lack of essential fatty acids may cause eczematous rash and thrombocytopenia
1) Fatty acids+alkali metals and alkaline earth metals form ____and which of them are soluble
2) Fatty acids +glycerols ____
3) FAs +other alcohols___
4) example and function of waxes
1) salts (remember salts of Na,K,Ca and Mg are called soaps) salts of Na and K are soluble while those of Ca and Mg are insoluble.
2) glycerides
3) waxes
4) beeswax ,lanolin derived from wool used as a base for many ointments and creams,spermaceti used in cosmetics and candles and by pharma’s
Neutral fats other name 2)function 3)oils 4)odour and taste of butter 5)how can we prevent rancidity of fats (working)
Triacylglycerols
2) main storage and transport form of lipids.
3) liquid fats are called oils
4) pure fats and oils are colourless and odourless, color of butter is due to carotene while it’s taste is due to i)diacetyl io)3-hydroxy 2-butanone which are produced by bacteria
4) by adding antioxidants like vit A,C,E* …antioxidants have greater affinity for O2 than oils and fats
Lipid classification
Simple lipids(neutral fats +waxes)
Compound lipids [ gylcolipids,gangliosides,sulfolipids+lipopolysachharides+lipoproteins{chylomicrons,VLDL,IDL,HDL,LDL}+phospholipids [{sphingolipids(sphingomyelina)+glycerophospholipids(phosphatidic acid+lecithin+cephalins+plasmalogens)}]
Phosphatidic acid
parent and simplest Type of GPL in which one of FA is replaced by phosphoric acid….present in cell
Lecithins… it’s a strong ___ and functions
Type of GPL in which choline is added to phophoric acid.choline is trong basic like NaOH
Abundant phospholipid in bile and serum it’s also important constituent of lung surfactant
Cephalins
These GPL are like lecithin but base choline is replaced by ethanolamine ,serine or inisotol. Present in high conc. in brain tissue.take part in clotting of blood
Plasmalogens
In these GPL base is ethanolamine though choline and serine are also present ….. chiefly found in skeletal muscles,heart,brain,liver and platelets.they cause platelets aggregation and de-granulation therefore were called platelets aggregation factor(PAF)…may cause pulmonary edema…they mediate acute inflammatory reaction and may cause anaphylactic shock..may cause neutrophils and macrophages to generate superoxide raficals
Sphingophosphospholipid
Sphingomyelin
Sphingosine
ceramide
Type of phosphilipid that contain sphingosine as it’s alcohol.
Important class of SPLs is sphingomyelin (made of sphingosine+fatty acids+phosphrylethanolamine or phosphorylcholine )which is present in myelin sheath in brain , nerve tissue and in smaller amount in blood.
Sphingosine is nitrogen containing 18-C alcohol.
Fatty acid + sphingosine —-> ceramide
Glycolipids
Other name
Also called cerebrosides
They are ceramide sugars (ceramide +hexose)
Present mostly in white matter of brain and myelin sheath of nerves.various types of glycolipids differ by FAs but cerebronic Acid(24-C fatty acid )is present in all glycolipids
Gangliosides
Composed of ceramide +galactosamine+
Chylomicrons-density and size
Produced in ___ from ___
Major carriers of TAGs
Hydrolized by____ into _____
Lowest in density largest in size
Produced in intestine from dietary lipids
Chylomicrons and vldl are major carriers of TAGs
Lipoprotein lipase into fatty acid and glycerol
Glycerol of chylomicrons is converted into ___
Is used for synthesis of TAGs or converted to DHAP.dhap is oxidized to produce energy (either through glycolysis or after conversion to glucose in liver).
VLDL- produced in___ by _____
Hydrolyzed by ____ into _____
Liver by combining TAG,cholesterol,apoproteins,phospholipids
Lipoprotein lipase into fatty acid,glycerol and IDL
LDL
Produced in___ by
Have highest concentration of ____
Î level of LDL is associated with î risk of ___ diseases
In plasma by degradation of IDL
Cholesterol and it’s esters
Heart diseases
HDL synethesized by ___
Density
TAG and protein content
Î level of HDL cholesterol associated with
Function
Why women have lower chances if heart diseases
Liver and released in blood
Densest lipoprotein
Lowest TAG and highest protein content
Decreased risk of heart diseases i-e it’s cardioprotective
Pre-menopausal women have higher levels of HDL than men
Steroids
2) sterols
3) their compounds in body
1) non-saponifiable fraction of lipids
2) sterols are alcohol form of steroids
3) cholesterol,ergosterol,bile salts,male and female sex hormones and adrenal cortex hormones
Cholestrol -normal range-functions
Most abundant animal sterol.200mg/dl.variation is indicator of cardiac and vascular diseases.
Functions..not flexible hence contributes to rigidity of cm.precursor of bile acids ,steroid hormones and vit d3.prevents water evaporation from skin
Bile composition
Bile acids-(cholic and chenodeoxycholic acid, glycine forms amide linkage n becomes glycocholic acid and glycochenodeoxycholic acid,)
Bile salts* :-k or Na -glycocholic acid or glycochenodeoxycholic acid or taurocholic acid…..these conjugated forms of bile salts are known as primary Bile salts and are BEST detergents and act as emulsifying agents..reabsorbed in ileum
Lecithin*
Bilirubin and billiverdin
K na and bicarbonates
Cholelithiasis
If movement of cholesterol from liver into bile salts is disrupted then more cholesterol enters bile that cannot be solubilised by lecithin and bile salts… then cholesterol precipitates in gall bladder initiating gallstone formation
Prostaglandins
These are related compounds i-thromboxanes and leukotrienes
Functions:-cause smooth muscle contraction eg intentinal and uterine(induces labor)
2)regulate menstruation and fertility
3)lower bp
