Final long Qs Flashcards
(15 cards)
Name vitamins that play a role of coenzymes in the organism.
vitamin b1- thiamine
vitamin b2- riboflavin- precursor for coenzymes
vitamin b3- niacin
vitamin b5- pantothenic acid
vitamin b6- piridoxine
vitamin b7- biotin
vitamin b9- folic acid
vitamin b12- cobalamin
vitamin c- ascorbic acid (-acts as antioxidant)
Next choose one representative (of the coenzyme vitamins) and describe its biochemical function, present the most important reactions in which is it involved, draw the structural formula of its active form and list symptoms of deficiency in humans and animals
Biochemical function
vitamin B2 is a precursor for coenzymes
FMN and FAD is formed by transfer of an adenosine monophosphate from ATP to FMN.
FMN and FAD can both accept 2 hydrogen atoms, forming FMNH2 or FADH2.
sources of riboflavin: liver, kidneys, heart, eggs, milk, yogurt,cheese, whole grain cereals, dark green leafy veg.
Vitamin b2 is sensitive to light but remains stable under heat and refridgeration.
Vitamin B2 requirement are increased during periods of strong growth, such as pregnancy and lactation.
Deficiency
Vitamin B2 riboflavin deficiency -> vascularisation of cornea followed by ulceration and secondary infection.
other ocular signs are conjunctivitus, excessive lacrimation and photophobia.
Describe the role of the kidneys in the maintenance of glucose homeostasis in the body
kidneys contribute to glucose homeostasis via 3 different mechanisms:
1. the release of glucose into the circulation via gluconeogenesis
2. the uptake of glucose from the circulation to satify its own energy needs
3. the reabsorption of glucose from the glomerular filtrate
Name the main proteins found in milk and shortly describe their structure and function
What is the main difference in the composition of milk proteins in human and cow milk
Casiens and whey proteins are the main proteins found in milk production.
>Casiens
Casiens are present in milk in large aggregates called casien micelles, which also contain colloidal calcium phosphate.
β-casien is the primary casien in human milk and with k-casien being the 2nd highest and αs1- and αs2- are not present in human milk (αs1- casien is the most common cause of milk allergy in humans)
Cows milk has high amounts of β-casien but also larger amounts of amounts of αs1- and αs2- than human milk.
k-casien protects a+b casiens from precipitation from Ca2+ ions, but k-casiens are easily attacked by renin.
>Whey proteins
Four major proteins include
β-lactoglobulin which forms dimmers in pH 3-7 and is NOT present in human milk
α-lactoglobulin - a rich source of trytophan
immunoglobulin - antibodies synthesised in response to stimulation by specific antigens
serum albumin- identical to blood serum albumin
Describe the function of hormones produced from tyrosine. Your answer should also
include the structure of these hormones and place of synthesis
Dopamine, nor, ad, T4,T3
Describe shortly the steps of xenobiotics detoxification
Phase 1- xenobiotics undergo chemical reactions (oxidation, reduction, hydrolysis, hydration) often by enzymes cytochrome p450 to introduce or expose functional groups on the molecule. This makes it more reactive.
Phase 2- conjunction involves the addition of water soluble molecules to the functional groups introduced in stage 1. This makes xenobiotics more water soluble and facilitates secretion.
Phase 3- excretion by intestines
Vitamins that function as hormones.
vitamin D,
vitamin A,
vitamin K,
Vitamin E - (more of an antioxidant)
Pick one (antioxidant vitamin) and draw its structure, what they do, their deficiency and their active form
Vitamin D,
Calcitriol -> functions primarily to regulate calcium and phosphorus homeostasis, working alongside parathyroid hormone. regulating calcium and phorsphorus concentration in blood.
in intestinal epithelium & cells it funtions as a steroid hormone.
Deficiency -> Rickets in children, osteomalacia in adults.
Rickets-> continued formation of collagen matrix of bone, but incomplete mineralization resulting in soft, pliable bones,
Osteomalacia-> demineralization of pre-existing bone making them susceptible to fracture
Role of the liver in amino acid metabolism
-oxidative deamination of amino acids resulting in formation of ketoacids and NH3
-transamination of amino acids resulting in formation of intermediate products of Krebs cycle
-synthesis of urea in urea cycle
-synthesis of amino acids such as glutamine and taurine
Different in components and functions of milk vs colostrum
Colostrum
- produced by all mammals during pregnancy (first form of milk, from mammary glands)
- available in the days after birth
- thick, yellowish form of milk
- higher in both fat and protein (fat in horses and sheep)
- packed with nutrients and antibodies that newborns need for protection (immunoglobulins)
- strengthening immune and digestive systems of baby
- mild laxative effect
Milk
- produced by all mammals after colostrum production stopped
- can be produced for months or years after birth
- thinner and whiter
- higher in fat in e.g. humans and camels
- rich in protein, calcium, potassium, iodine, phosphorus and vitamin B2, B12
- proteins aid digestion, fat for brain development, lactose for energy
Energy for muscle during different durations of metabolism (e.g. Short – phosphocreatine,
long – aerobic glycolysis)
Explain why copper is an important microelement. Your answer should include biochemical functions of Cu, symptoms of defieceny and related diseases in animals and humans?
Copper is an essential constituent of several enzymes. and so is involved in many metabolic reactions.
Copper in ceruloplasmin helps in the incorporation of fe in hemoglobin, assists in the absorption of Fe from the gastrointestinal tract.
Copper is necessary for the hematologic and neurologic systems
It is necessary for the growth and formation of bone, and formation of myelin sheaths.
Deficiency
deficiency in animals can be recognised by anemia, reduced growth rate, connective tissue disorders, generalised osteoporosis, increases susceptibility to all diseases, Swayback, de pigmentation of skin, hair, wool.
Menkes disease is a genetic disorder of Cu deficiency.
Describe the role of kidneys in amino acids metabolism (specific reactions taking place in the kidneys as well as amino acids that are synthesied in this organ)
What is the funtion of lactose in milk? How and where is it synthsised? What causes lactose intolerance.
Lactose= disaccharide
plays a role in milk synthesis, is a major osmole, draws water into milk during lactose synthesis.
Lactose Synthesis
-takes place in Golgi apparatus of mammary epithelial cell.
-process involves conversion of glucose and galactose into lactose by lactose synthase.
-GLUT 1 transporters are needed on cell membrane and on Golgi membrane to transport the glucose.
-Lactalbumin + B4 galactosyl transferase catalyze the formation of lactose from glucose + galactose.
Lactose Intolerance
- due to lack of enzyme Lactase (Beta galactosidase)
-Lactase is needed to hydrolyze B1-4 glycosidic bonds in lactose.
Children’s vs Adults intolerance:
Children: high concentration of lactose is present in neonates, it naturally declines after weaning resulting in:
Primary Hypolactasia: lactase deficiency and lactose malabsorption.
Adults: Secondary hypolactasia: short term + reversible condition as a result of damage to intestinal mucosa brush borders, this increases GI transit time.
