Lab Exam

• sodium/ calcium exchangers 
• calcium/ proton ATP- ases 

• Vit. D defficiency results from a combination of inadequate exposure to sunlight and decreased dietary intake of Vit. D
• causes problem with bones in children - Rickets (bowed long bones) and in adults Osteomalacia (softening of bones)

is the softening of the bones caused by a vitamin D deficiency in adults.

Characterized by impaired mineralization of newly synthesizen bone matrix 

Intracellular protein that ferries Calcium across the intestinal epithelial cells 

• 80 kDa glycoprotein with two homologous iron- binding domains 
• transferrs 2 Fe3+ irons

• also named ceruloplasmin 
• reoxidizes Fe²⁺ to Fe³⁺ in the blood 

1. Mitochondria & Endoplamic Reticulum 
2. sodium/calcium exchangers or calcium/ proton ATP-ases

1. sunlight 
2. 7- dehydrocholesterol

3 locations are: SKIN, LIVER, KIDNEY

Vitamin D₃ or D₂ (Cholecalciferol) must be metabolized to the hormonally active form (1,25-dihydroxycholecalciferol)

2 Steps: 

1. in LIVER: calciferol → hydroxylation →25- hydroxycholecalciferol 
2. in KIDNEY: 25- hydroxycholecalciferol →hydroxylation → 1,25-dihydroxycholecalciferol 

1. Vitamin D 
2. Parathyroid hormone 
3. Calcitonin

• known as beta-1B-glycoprotein

• binds heme with the highest affinity of any known protein

• protects the body from the oxidative damage that free heme can cause

• preserve the body's iron

• major Iron storing protein (mostly in liver)

• can store about 4500 iron (III) ions

• Complex formed when ferritin capacity is exceeded

• Formed by hydroxide ions, iron ions and phosphate

• Excessive levels of hemosiderin → deposited in heart and liver and can lead to impaired organ function

  (cardiomyopathy and liver cirrhosis)

Calcitonin reduces the calcium and phosphate reabsorption in the kidneys, therefore more calcium and phosphate are excreted in the urine

Regulatory mechanism for excess calcium and phosphate in the body

• NO synthesis from Arg in the endothelial cells is induced by calcium (stimulated by bradykinin or acetylcholine).

• NO diffuses to vascular muscle cells and activates guanylate cyclase which generates cGMP.

• cGMP activates protein kinase PK-G and triggers relaxation of the smooth muscle and dilation of the

  vessels.

⇒VASODILATOR

• Similar effect is observed by the action of atrial natriuretic peptide (ANP); Sildenafil citrate, popularly known by the trade name Viagra

• Other hormones: parathyroid hormone (renal vasodilation), corticotrophin-releasing hormone (CTRH, vasodilation in skin)

99% stored in bones though, only 1% active in body functions

1. Signal transduction
2. Mineralization
3. muscle contraction
4. fertilization
5. vision
6. nerve conduction,
7. exocytosis
8. cell division

• hereditary disorders which are clinically progressive
• an accumulation of glycosaminoglycans in various tissues

 →caused by the absence of malfunctioning of lysosomal enzymes which are needed to break down molecules called  glycosaminoglycans 

• varying degrees of severity 
• affects bone, skeletal structure, connective tissues and organs 
• neurological complications include damage to neurons 

• Iron uptake is regulated at basal membrane by the iron binding protein apoferritin

• DEPLETED state of iron, LESS apoferritin is synthesized, iron diffuses through membrane freely.

• REPLETED state, synthesis of apoferritin is HIGH, iron binds to ferritin 

• Most iron are bound to ferritin, after cellular turnover and slough, iron is released back into intestine

  and NOT being ABSORBED at all.

substances foreign to the organism (medicinal drugs, pollutans, insectisides, cigarette smoke etc.)

1. Regulation of Blood Glucose Level
2. Nucleotide Biosynthesis
3. Synthesis & Export of Cholesterol & Triacylgycerol 
4. Synthesis of Blood Proteins
5. Ammonia & UREA cycle
6. Synthesis of Glycoproteins & Proteoglycans
7. Formation of Keton Bodies
8. Pentose- Phosphate Pathway 
9. Bile secretion
10. Biotransformation reaction of Xenobiotics 

1 Phase: 

reactions are performed by cytochrome P450 enzymes - hydroxylation, deamination, dehalogenation, desulfuration,epoxidation, peroxigenation, reduction
reactions performed by other enzymes - hydrolysis 

2 Phase:

products produced in Phase1 are converted by specific Enzymes to various polar metaboites by conjugation, sulfatation, mathylation, glucoronidation

• conjugation with glutathione 
• Acetylation
• Methylation
• Glucoronidation
• Sulfatation

1. Ferritin
2. Apoferritin
3. Teansferrin

• hexamer consisting of two identical heavy chains (223 kDa) and four light chains (16 kDa and 20 kDa).

• A single myosin molecule is shaped like a golf club.

• Each heavy chain has a globular "head" at its amino-terminal end and a long "tail" of about 150 nm length.

• In the tail region, the two chains intertwine to form a superhelix, while the four smaller subunits are attached to the globular heads.

• The enzyme acetylcholinesterase converts acetylcholine into the inactive metabolites choline and acetat

• Iron regulatory protein are stem-looped sections of mRNA that are involved in the production of ferritin and transferrin receptors.

• These elements are 'responsive' to iron because their binding proteins change their conformation in response to intracellular iron levels, thus providing a feedback mechanism to regulate intracellular iron .

• In response to high intracellular iron levels, increased production of ferritin , and decreased production of transferrin receptor to reduces the cellular uptake of iron.