Thursday, April 26, 2012
Myoglobin
Myoglobin is abundant in muscles involved in laborious activity. Why ?
To know the answer, let's begin with some basics.
Myoglobin contains only one polypeptide chain which contains only one Haem molecule. One Haem molecule can bind to only one O2 molecule.
Quaternary structure is possible only in the presence of >1 subunits in a protein. As Myoglobin is made up of a single polypeptide chain, Quaternary structure is NOT possible. As there is no Quaternary structure, Bohr effect, 2,3 BPG effect and co-operative effect are not possible. After all there is only one O2 in haem. So there is no role for co-operative effect. (As there is no co-operative effect, Oxygen dissociation curve of myoglobin is hyperbolic in shape)
Myoglobin has very high affinity for oxygen. Why ?
Myoglobin is NOT an Oxygen carrier. It is just an oxygen reservoir. Whenever the oxygen tension is critically low in the myocyte it releases its Oxygen.
This is why Myoglobin is abundant in muscles with high activity.
Monday, April 23, 2012
Vit B12
Here are some high yield facts about vitamin B12.
- Only water soluble vitamin stored in the body. (other only's of special mention)
- Contains 2 C - Cobalt and Corrin ring (other rings of biochemical importance)
- Present only in foods of animal origin (Curd is of animal origin!) So, pure vegans are prone to B12 defeciency (think of Gandhi)
Though Intrinsic factor of castle is secreted by parietal cells of stomach, it can not bind to B12 in the stomach. Why ? B12 in the food is released by gastric juice and B12 binds to cobalophilin, a salivary protein. In the duodenum, cobalophilin is hydrolysed --> IF binds to B12 . Both gets absorbed in distal ileum.
- Co-enzyme for 3 enzymes in the body - 1) Methyl malonyl CoA mutase 2)Methionine synthase 3) Leucine aminomutase. (other 3's and 4's with exam point of view)
- Deficiency results in methyl malonyl aciduria (Xanthurenic acid - B6; FIGLU - folate)
- Folate is trapped in the form of methyl THFA in B12 defeciency.
- Megaloblasts are NOT seen in peripheral smears. seen in bone marrow examination. You can see macrocytes in peripheral smear.
I hope you know everything about pernecious anemia, blind loop syndrome etc.,
- Cyanocobalamin is the synthetic form found in vitamin tablets. It releases negligible amounts of cyanide in the body.
Injection B12 is given for patients with diabetic neuropathy as it is important of myelin synthesis.
I am preparing an audio which contains more detail on the text given in Green. Keep visiting the blog for more updates. Leave your comments below.
Sunday, April 15, 2012
Saturday, April 14, 2012
Friday, April 13, 2012
Wednesday, April 11, 2012
Monday, April 9, 2012
Inhibitors of Electron Transport Chain
Inhibitors of Electron Transport Chain
Most of the friends answered wrongly in the quiz.Don't forget ! Fo is not F zero. O is for Oligomycin.
It is my duty to put a small note on ETC inhibitors as this topic is very important for exams.
Amobarbital & Rotenone --> Complex I (NADH dehydrogenase-CoQ.)
Rotenone and MPTP (a neuro-toxin) --> Inhibits complex I and causes Parkinsons like features
Antimycin A - inhibits --> Complex III (Q-cytochrome c oxidoreductase)
H2S, CO & Cyanide --> inhibits complex IV (Cytochrome Oxidase)
Oligomycin --> inhibits Fo component of ATP synthase
Atractyloside --> inhibits Translocase
Thermogenin --> brown adipose tissue,physiological uncoupler
Thyroxine
Dinitrophenol --> uncoupler
Discussion of Biochemistry - Carbohydrates part I - NEET pattern
Discussion of Biochemistry - Carbohydrates part I - NEET pattern
1. Inulin
Inulin is a homopolymer of fructose and contains least amount of glucose at the terminals.
As inulin is neither absorbed nor secreted in kidney, use for GFR estimation
Human enzymes can attack only alpha glycosidic linkage. As inulin and cellulose contain beta glycosidic linkage they are not digested. Cellulose is fermented by the help of intestinal bacteria. Pectin is neither digested nor fermented.
2. Insulin Inhibits Glycogen Phosphorylase
Glycogen phosphorylase increases blood sugar. So insulin will inhibit it. This is easy.
I want you to memorize this simple fact --> Whichever enzyme increases the blood glucose will be active in phosphorylated form.
3. Epimers
Epimers differ around a single carbon. Galactose is C4 epimer of glucose. Mannose is C2 epimer of glucose. Galactose and mannose are NOT epimers as they differ in more than one carbon
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| 4 Girls and 2 Man |
I guess you know everything about rest of the questions. If you really want, inform me.
Saturday, April 7, 2012
Prepare for PGI entrance - for Beginners
PGIMER (Post Graduate Institute of Medical Education and Research), Chandigarh conducts entrance exams in the months of November and May each year.
NEET/CET won't cover AIIMS, PGIMER, JIPMER, NIMHANS and other Institutes of National importance.
As there is no MBBS course in PGI, postgraduate students in basic science and para-clinical departments can concentrate more in research. This is a golden opportunity indeed!
PGI Exam contains 250 questions. Each question contains 5 possible answers. Single correct answer, Multiple correct answers & No correct answer are possible. The worst thing is you have to shade more than one circle and it takes lot of time too.
Number of questions in each subject as given in prospectus:
Applied Anatomy - 6
Applied Biochemistry-12
Immunogenetic & Molecular Biology-10
Applied Physiology- 6
Pa t h o l o g y - 1 5
Ph a r m a c o l o g y - 1 2
M i c r o b i o l o g y - 1 2
S o c i a l &Preventive Medicine-7Fo r e n s i c M e d i c i n e - 6
Medicine-36
Paediatrics-12
Dermatology-6
Psychiatry-6
Radiodiagnosis-6
Radiotherapy-6
Surgery-36
ENT-10
Ophthalmology-10Orthopaedics -10
Anaesthesia-6
Subjects having highest weightage are highlighted. Concentrate on these subjects.Obst & Gynaecology-20.
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