Metabolism of macromolecules Flashcards
What is the minimal carbon number for carbs
3
What is the bond existing in cellulose, glycogen, amylose and amylopectin respectively
beta-1,4-glycosidic; alpha-1,4-glycosidic& alpha-1,6-glycosidic; alpha-1,4-glycosidic; alpha-1,4-glycosidic & alpha-1,6-glycosidic
What is the product of Amylose degradation and amylopectin degradation
glucose, Maltose and maltotriose; alpha-limiting dextrins (polysachharide then into maltose)
What does the pancreatic and salivary alpha-amylose break
Alpha 1,4-glycosidic bonds
Which protein is responsible for the cleavage of most carbs
glycosidases
Where are glycosidase located
On the brush border of enterocytes
How is glucose uptaken into enterocytes
It is uptaken via Na/Glucose transporter 1(SGLT1) against conc gradient by coupling it’s transport to that of Na+, then into blood at basolateral plane via GLUT2
Why fructose uptake is less effective
It is because the uptake of fructose is via GLUT5 hence it has no coupling effect of Na+ uptake.
Suggest, what are the 2 phases in Glycolysis
Energy investment phase and energy generation phase
Name the intermediates for glycolysis
Glucose 6-P, Fructose 6-P, Fructose-1,6-bisP, Pyruvate
Name the antagonist reaction for glycolysis
Gluconegenesis
When will anaerobic glycolysis take place
When there is insufficient oxygen
How is lactate transported out of the cell
Via monocarboxylate transporter (MCT)
How to let lactate re enter respiration
Lactate +NAD+ –> Pyruvate + NADH +H+
Is there any carbohydrate that the body cannot synthesis but is necessary
No (All can be derived from glycogen)
Name a compound that can be synthesized by glucose that has reducing power
NADPH
Name a compound that is synthezied from glucose that involves in RNA production
ribose-5-phosphate
What is the test usually done in Hospital that requires appointment to assess body’s response towards Glucose challenge. Suggest the 3 procedures
OGTT, Oral Glucose Tolerance Test
- Fast for 8h and withdraw blood
- Patient drink a glucose solution with glucose amount= (17.4g/kg of body mass)
- Withdraw blood In regular interval (30min) until 2h past the drinking of solution
Suggest should be avoided 3 days before OGTT
Alcohol, unnecessary drugs, Too much/Too little bed rest, salicylates, diuretics, anticonvulsants, fever (??)
Suggest how BGL can be determined by blood sample
- Glucose is oxidized by glucose oxidase to form gluconic acid and Hydrogen peroxide
- Hydrogen peroxide is split into water and oxygen by peroxidase
- Oxygen oxidizes o-dianisidine from colourless to brown
Suggest the term that describes being freezed and dried
lyophilized
What are the 7 types of fat
Bile salt,
Eicosanoids (Arachidonic Acid derivates, prostaglandins, thromboxanes, leukotrienes, lipoxins)
Steroids
Triacylglycerol
Phospholipids
Vitamins (ADEK)
Cholesterol
Why cis unsaturated fatty acids are good
They have C=C ,which can make it kink
Name the first site of fat digestion, the enzyme and the product
Stomach, Lingual Lipase and Human Gastric Lipase, diacylglycerol
Name the 2 hormone that involves in lipid digestion and their function
Cholecytostokinin: stimulate the gall bladder and pancreas to squeeze to release bile and pancreatic juice respectively
Secretin stimulates to release of NaHCO3 by pancreas and inhibits the secretion of gastric juice to raise intestinal pH
What is the main site of lipid digestion and the names
intestine. Colipase, pancreatic lipase, etc
What is the product of TAG hydrolysis
2FFA (Free Fatty acid) and 2-monoacylglycerol
What are the differences in pathway between short/medium FFA and long ones
Short/Medium
1. Forming michelle/directly pass the water layer overlying microvilli
2. Enter blood directly and bind to albumin
Long
1. Form michelle to pass the water film
2. Enter enterocytes to be packed into TAG, bind to chylemicron to reach lacteal, entering the thoracic duct, entering lymphatic system and return to blood at the left subclavian vein
How can lipid exist in lymph
In chylemicrons (a lipoprotein),
How can lipid exist in blood
Binding to albumin
What is the compostional difference between michelle and lipoprotein
Michelle is usually made of phospholipid forming a sphere, or a bile acid at centre in intestinal lumen.
Lipoprotein is the combination of protein (apolipoprotein) and lipid, with a hydrophobic cholesterol +triacylglycerol core and a outershell formed by phospholipid and non-esterified cholesterol
What is the structural and functional difference between the 2 types of adipose tissue
Brown adipose tissue is to generate heat without shivering, hence contains a lot of mitochondrion that contributes to it’s brown colour to release heat by respiration
White adipose tissue is for storing TAG inside the cell
What is the minor storage site for TAG
Liver and skeletal muscles
What does Lipoprotein Lipase do
It hydrolyses TAG in chylemicron and IDL (derives from VLDL)
What is the fate of the FFA produced from above reaction
it becomes Fatty Acyl Co-A (FA Co-A)
What is the action of insulin on adipocytes
It stimulate the expression of GLUT 4 on the cell membrane to uptake more glucose
What is the fate of glucose in adipocyte
It becomes dihydroxylacetone glucose (DHAP) then glycerol 3-phosphate (G3P)
Write the equation for formation of TAG in the adipose tissue
FA Co-A + G3P –> TAG
Under what circumstances will TAG be used for lipolysis. What are the procedures
Under high glucagon or low insulin. It activates hormone sensitive lipase to cleave TAG
What is the fate of FFA and glycerol released in loiver respectively
FFA: For beta-oxidation to release a lot of energy and Acetyl Co-A
Glycerol: Used for gluconegenesis to make Glucose
WHat is the fate of Acetyl CO-A formed in beta-oxidation
To feed into TCA cycle or to make ketone bodies (Under prolonged fasting)
Name a compound that is from TCA to make FA
Citrate (to Acetyl Co-A then malonyl Co-A via Acetyl Co-A carboxylase then to palmitate (via Fatty Acid Synthase) then FA CoA
Where is the conversion take place
Cytosol
Name the enzyme that cleaves protein in stomach and it’s way to activate
Pepsin. It is activated by self-cleaving of pepsinogen under low pH
Name 4 zymogens secreted by pancreas
trpsinogen, chymotrysinogen, proelastase, procarboxypeptidases
What is the difference between endopeptidase and exopeptidase
One cut the peptide bond at the middle, one cut at the linear end
Name an exopeptidase
aminopeptidase (on brush border of enterocytes and inside)
What drives the uptake of amino acids,dipeptides and tripeptides
By the energy generated by SOdium-Potassium ATPase pump. THen by faciliated transporter to enter blood
Explain how polypeptide can enter blood
They may slip between cells that lines the gut wall
Pinocytosis
Name 1 source of endogenous source of amino acid
Protein turnover
What is transamination
It involves transfering the amino group of an amino acid to a Alpha-keto acid to make it an amino acid
How can body utilize amino acid as energy source via transamination
By transamination to form alpha KG which is a intermediate of TCA cycle
What is the fate of the carbon skeleton of amino acid
Into Triacylglycerol (secreted in liver in VLDL) or glucose
Name 2 amino acids that has their amino groups removed in deamination to make urea
Glutamate, Asparate
Name 3 possible fate for the amino group of glutamate
Transfered to a keto acid, as ammonia or as ammonium ion
What;s the name of hvign too mucb ammonia and ammonium ion respectively. What’s the associated problem
Hyperammonia/ Hyperammonemia
It causes neurotoxic conditions to brain cells
What is the source for the 2 nitrogen atom of urea from
Ammonia and Asparate
Name 2 nitrogen carrier in human body
Alanine, glutamine
Where is alanine formed in the transport of urea. Whats the raw material
Skeletal muscles from pyruvate
What is the fate of the carbon of alanine
It becomes pyruvate then glucose by gluconeogenesis
What is the fate of the Nitrogen of Alanine
For urea synthesis
At liver, what does ketoglutarate form
Glutamate
What is the involved enzyme
alanine aminotransferase
What is the fate of Glutamate formed
It can be used to form a-ketoglutarate by losing 2 ammonium to form urea forming 1 NADH, or undergoes transamination with oxaloacetate to form a-ketoglutarate and asparate which forms urea
How is glutamate made in muscle
a-ketoglutarate –> (GDH) Glutamate –> (glutamate syntherase) Glutamine
