Sub cellular organellesand

Cell membranesSub cellular organelle

Marker Enzyme

Mitochondria Inner membrane;ATP synthase

Lysosome Cathepsin

Golgi complex Galactosyl transferase

Microsomes Glucose-6-transferase

Cytoplasm Lactate dehydrogenase

Sub cellular organelles and marker enzymes

Reference : Textbook of Biochemistry for Medical Students by DM Vasudevan 7th Ed. Pg 11

Fluid mosaic modelLipid bilayer originally proposed by Davson and Danielle was later described as a fluid mosaic model by Singer and Nicolson.The distribution of the phospholipids is such that choline containing phospholipids are mainly in the external layer and ethanolamine and serine containing phospholipids in the inner layer.Each leaflet is 25 A thick, with the head portion 10 A and tail 15 A thick. The total thickness is about 50 to 80 A.

This flip-flop movement is catalyzed by enzymes. Flippases catalyze the transfer of amino phospholipids across the membrane.Floppases catalyze the outward directed movement, which is ATP dependent.The nature of the fattyacids also affects the fluidity of the membrane, the more unsaturated cis fatty acids increase the fluidity. Reference : Textbook of Biochemistry for Medical Students by DM Vasudevan 7th Ed. Pg 14

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Hydroxyamino acids

Serine ( Ser) Threonine ( Thr )

Sulfur containing amino acids

Cysteine ( Cys ) Methionine ( Met )

Amino acids with amino group

Asparagine ( Asn ) Glutamine ( Gln )

Dicarboxylic amino acids

Aspartic acid ( Asp ) Glutamic Acid ( Glu)

Dibasic amino acids

Arginine ( Arg ) contains Guanidium group

Lysine ( Lys )

Aromatic amino acids

Phenylalanine ( Phe )

Tyrosine ( Tyr )

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PHENYLKETONURIA

Caused by Phenylalanine hydroxylase deficiencyRecessive condition

Guthrie Test

Clinical Manifestation

Mental RetardationAgitationHyperactivityTremorsConvulsionsHypopigmentation

DiagnosisBlood phenylalanine - level >20mg/dlTandem Mass SpectrometryFerric Chloride testDNA Probes

Treatment Diet containing low Phenylalanine

1 - Phenylalanine hydroxylase1A - NADPH dependent reductase

Reference : Textbook of Biochemistry for Medical Students by DM Vasudevan 7th Ed. Pg 236

AIIMS ‘18

Mousy Body Odour due to Phenyllactic acid

Hypopigmented hair

Albinism

Autosomal Recessive DiseaseAbsent Tyrosinase - defective synthesis of Melanin.

Clinical Manifestations

i. Hypopigmented ocular fundusii. Red or Gray irisiii. Photophobiaiv. Nystagmusv. Decreased visual acquityvi. Nevi and Melanomas in skin

NEET ‘19

Reference : Nelson Textbook of Pediatrics 30th Ed Pg 642

Red Iris

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Classification of Albinism

Oculocutaneous Albinism

i.OCA 1 - Tyrosinase Negative ii.OCA 2 - Tyrosinase Positiveiii.OCA 3 - Rufos Albinismiv.OCA 4

OCULAR Albinism

Nettleship - Falls Type

Most common type among Generalised OCA is : OCA 2Syndromes associatedi. Hermansky Pudlak Syndromeii. Chediak - Higashi syndrome

Localised albinism

Localised patches of hypopigmentation of skin and hair

Piebaldism

Autosomal DominantBorn with white forelockWhite macules on the face,trunk and extremities.Mutation in KIT gene present.

Autosomal DominantFour Major Types :

Type I - Most commonType IIType IIIType IV - Associated with Hirschsprung disease

Waardenburg syndrome

Clinical Manifestation

White forelockLateral displacement of inner canthi of eyesBroad Nasal BridgeHeterochromia of IridesSensorineural deafness

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Plasma proteins

Normal ELECPHOREtic pattern of plasma proteins

Densitometer scanning reveals the relative mobilities of albumin, α1-globulin, β2-globulin, β-globulin, and γ-globulin.

Separated bands of protein

Protein losing enteropathy

Loss of albumin and gamma globulinsSlight increase in the Alpha 2 band is due to a stressful stimulus

Normal ELECPHOREtic pattern of plasma proteins

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EnzymesGeneral enzymology

Gibbs free energy curve

It denotes a portion of total energy change in a system that is available for doing work.

G = H - T S

GHS

= Change in free energy= Change in Enthalpy= Change in Entropy

AIIMS ‘20

Factors influencing enzyme activity

1. Enzyme concentration2. Substrate concentration3. Product concentration4. Temperature5. Hydrogen ion concentration (pH)

6. Presence of activators7. Presence of inhibitors8. Presence of repressor or derepressor9. Covalent modification.

Enzyme concentration

Rate of a reaction or velocity (V) is directly proportional to the enzyme concentration, when sufficient substrate is present.

Reference : Textbook of Biochemistry for Medical Students by DM Vasudevan 7th Ed. Pg. 56

The activation energies, G , for the S P and P S reactions are indicated.G is the overall standard free-energy change in the direction S P.

Reference : Lehninger Principles of Biochemistry 4th edition Pg. 194

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Osazone Formation

All reducing sugars will form osazones with excess of phenylhydrazine when kept at boiling temperature.Osazones are insoluble.Each sugar will have characteristic crystal form of osazones.Osazones may be used to differentiate sugars in biological fluids like urine.Needle shaped crystals ( Glucose )

Needle shaped crystals ( Fructose )

Needle shaped crystals ( Mannose )

Balls with thorny edge shaped crystals(Galactose)

Cotton ball shaped crystals ( Lactose )

Sunflower shaped crystals ( Maltose )

Fine long needle shaped crystals ( Xylose )

Reference : Textbook of Biochemistry for Medical Students by DM Vasudevan 7th Ed. Pg. 74 http://jmscr.igmpublication.org/v4-i12/14%20jmscr.pdf

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