BIOCHEMISTRY medpgnotes

BIOCHEMISTRY

www.medpgnotes.com

1 GENERAL BIOCHEMISTRY

CONTENTS GENERAL BIOCHEMISTRY .............................................................................................................................................. 6

GENERAL FEATURES OF BIOCHEMISTRY ................................................................................................................... 6

STUDIES ..................................................................................................................................................................... 6

BONDS ....................................................................................................................................................................... 6

PH AND BUFFERS ...................................................................................................................................................... 7

ENERGY ..................................................................................................................................................................... 7

PATHYWAYS IN CYTOSOL AND MITOCHONDRIA ...................................................................................................... 7

CARBOHYDRATES .......................................................................................................................................................... 8

EPIMERS AND ENANTIOMERS ................................................................................................................................... 8

STRUCTURE OF CARBOHYDRATES............................................................................................................................. 8

GLUCOSE TRANSPORTERS ....................................................................................................................................... 10

CORI CYCLE .............................................................................................................................................................. 10

GLUCOSE ................................................................................................................................................................. 10

GLYCOLYSIS ............................................................................................................................................................. 12

ACETYL COA ............................................................................................................................................................ 13

KREB’S CYCLE .......................................................................................................................................................... 13

GLUCONEOGENESIS ................................................................................................................................................ 15

GLYCOGENOLYSIS .................................................................................................................................................... 15

ELECTRON TRANSPORT CHAIN ................................................................................................................................ 16

HMP SHUNT ............................................................................................................................................................ 17

GLUCOSE 6 PHOSPHATE DEHYDROGENASE DEFICIENCY ........................................................................................ 18

FRUCTOSE METABOLISM ........................................................................................................................................ 18

LACTOSE METABOLISM ........................................................................................................................................... 19

GENERAL FEATURES OF GLYCOGEN STORAGE DISORDERS .................................................................................... 19

VON GIERKE’S DISEASE ........................................................................................................................................... 20

DISORDERS OF GALACTOSE METABOLISM ............................................................................................................. 20

SUBSTRATE LEVEL PHOSPHORYLATION .................................................................................................................. 21

LIPIDS .......................................................................................................................................................................... 21

FATTY ACIDS ............................................................................................................................................................ 21

SYNTHESIS OF FATTY ACIDS .................................................................................................................................... 23

OXIDATION OF FATTY ACIDS ................................................................................................................................... 24

BIOCHEMISTRY

www.medpgnotes.com

2 GENERAL BIOCHEMISTRY

GENERAL FEATURES OF LIPOPROTEIN .................................................................................................................... 24

LIPOPROTEIN LIPASE ............................................................................................................................................... 24

CHYLOMICRON ........................................................................................................................................................ 25

LDL........................................................................................................................................................................... 25

VLDL ........................................................................................................................................................................ 26

HDL .......................................................................................................................................................................... 26

APOPROTEIN ........................................................................................................................................................... 27

CHOLESTEROL ......................................................................................................................................................... 27

HYPERCHOLESTEROLEMIA ...................................................................................................................................... 28

XANTHOMA ............................................................................................................................................................. 28

ABETALIPOPROTEINEMIA ....................................................................................................................................... 29

BILE ACIDS ............................................................................................................................................................... 29

KETONE BODIES ...................................................................................................................................................... 29

STARVATION ........................................................................................................................................................... 30

AMINOACIDS ............................................................................................................................................................... 30

GENERAL FEATURES OF AMINOACIDS .................................................................................................................... 30

PROLINE .................................................................................................................................................................. 32

VALINE ..................................................................................................................................................................... 32

LEUCINE................................................................................................................................................................... 32

ARGININE ................................................................................................................................................................ 32

HISTIDINE ................................................................................................................................................................ 32

GLYCINE ................................................................................................................................................................... 33

ALANINE .................................................................................................................................................................. 33

PHENYLALANINE ..................................................................................................................................................... 33

TYROSINE ................................................................................................................................................................ 33

TRYPTOPHAN .......................................................................................................................................................... 34

CYSTEINE ................................................................................................................................................................. 34

METHIONINE ........................................................................................................................................................... 34

HOMOCYSTEINE ...................................................................................................................................................... 34

ASPARTATE .............................................................................................................................................................. 35

GLUTAMATE ............................................................................................................................................................ 35

GLUTAMINE ............................................................................................................................................................ 35

LYSINE ..................................................................................................................................................................... 35

GLUTATHIONE ......................................................................................................................................................... 36

BIOCHEMISTRY

www.medpgnotes.com

3 GENERAL BIOCHEMISTRY

CREATININE ............................................................................................................................................................. 36

GENERAL FEATURES OF DISORDERS OF AMINOACID METABOLISM ...................................................................... 36

PHENYLKETONURIA................................................................................................................................................. 36

MAPLE SYRUP URINE DISEASE ................................................................................................................................ 37

MULTIPLE CARBOXYLASE DEFICIENCY .................................................................................................................... 37

HARTNUP DISEASE .................................................................................................................................................. 38

ALKAPTONURIA ....................................................................................................................................................... 38

AMMONIA ............................................................................................................................................................... 38

UREA ....................................................................................................................................................................... 39

GLUTAMATE DEHYDROGENASE .............................................................................................................................. 39

DISORDERS OF HEME SYNTHESIS ............................................................................................................................ 40

PORPHYRIN AND PORPHYRIA ................................................................................................................................. 40

PROTEINS AND ENZYMES ............................................................................................................................................ 41

STRUCTURE OF PROTEIN ......................................................................................................................................... 41

DETERMINATION OF PROTEIN STRUCTURE ............................................................................................................ 42

GLYCOPROTEINS ..................................................................................................................................................... 43

PROTEOGLYCAN ...................................................................................................................................................... 44

TYPES OF PROTEIN .................................................................................................................................................. 44

ESTIMATION OF PROTEINS ..................................................................................................................................... 44

DENATURATION OF PROTEINS ................................................................................................................................ 44

SEPARATION OF PROTEINS ..................................................................................................................................... 45

GENERAL FEATURES OF ENZYMES .......................................................................................................................... 46

OXIDASE .................................................................................................................................................................. 46

OXYGENASE ............................................................................................................................................................. 46

DEHYDROGENASE ................................................................................................................................................... 46

HYDROLASE ............................................................................................................................................................. 47

TRANSFERASE.......................................................................................................................................................... 47

LIGASE ..................................................................................................................................................................... 47

LYASE ....................................................................................................................................................................... 47

HOLOENZYME ......................................................................................................................................................... 47

TRANSAMINATION .................................................................................................................................................. 47

SERINE PROTEASE ................................................................................................................................................... 48

ENZYME INHIBITION ............................................................................................................................................... 48

ENZYME REGULATION............................................................................................................................................. 48

BIOCHEMISTRY

www.medpgnotes.com

4 GENERAL BIOCHEMISTRY

RIBOZYMES ............................................................................................................................................................. 49

ISOENZYMES ........................................................................................................................................................... 49

COMPONENTS OF ENZYMES ................................................................................................................................... 49

COENZYMES AND COFACTORS FOR ENZYMES ........................................................................................................ 50

INFORMATIONAL MACROMOLECULES ....................................................................................................................... 50

PURINE METABOLISM ............................................................................................................................................. 50

PYRIMIDINE METABOLISM ...................................................................................................................................... 51

STRUCTURE OF DNA ................................................................................................................................................ 51

HISTONE .................................................................................................................................................................. 53

MITOCHONDRIAL DNA ............................................................................................................................................ 54

TELOMERASE ........................................................................................................................................................... 54

REPLICATION OF DNA ............................................................................................................................................. 54

GENETIC CODE ........................................................................................................................................................ 55

INTRONS AND EXONS.............................................................................................................................................. 56

MUTATION .............................................................................................................................................................. 56

REGULATION OF DNA.............................................................................................................................................. 57

GENERAL FEATURES OF TRANSCRIPTION ............................................................................................................... 57

RNA POLYMERASE ................................................................................................................................................... 58

POST TRANSCRIPTIONAL MODIFICATION ............................................................................................................... 58

SPLICING .................................................................................................................................................................. 59

rRNA ........................................................................................................................................................................ 59

mRNA ...................................................................................................................................................................... 59

tRNA ........................................................................................................................................................................ 59

MICRORNA .............................................................................................................................................................. 60

RIBOSOMES ............................................................................................................................................................. 60

TRANSLATION ......................................................................................................................................................... 60

POST TRANSLATIONAL MODIFICATION .................................................................................................................. 62

PROTEIN FOLDING .................................................................................................................................................. 62

INBORN ERRORS OF METABOLISM ............................................................................................................................. 63

GENERAL FEATURES OF INBORN ERRORS OF METABOLISM .................................................................................. 63

TAY SACH’S DISEASE................................................................................................................................................ 63

GAUCHER’S DISEASE ............................................................................................................................................... 64

NIEMANN PICK DISEASE .......................................................................................................................................... 64

BIOCHEMISTRY

www.medpgnotes.com

5 GENERAL BIOCHEMISTRY

KEY TO THIS DOCUMENT

Text in normal font – Must read point.

Asked in any previous medical entrance

examinations

Text in bold font – Point from Harrison’s

text book of internal medicine 18th

edition

Text in italic font – Can be read if

you are thorough with above two.

BIOCHEMISTRY

www.medpgnotes.com

6 GENERAL BIOCHEMISTRY

GENERAL BIOCHEMISTRY

GENERAL FEATURES OF BIOCHEMISTRY

Presence of 2 extra pairs of electrons on the oxygen in water molecule results in

Electronegative charge on water molecule

Monoprotic acids Formic acid, Acetic acid, Nitric acid

Diprotic acid Carbonic acid, succinic acid, glutaric acid Tripotic acid Citric acid Crystal Molecules are arranged in same conformation and

same orientation

Farnesyl diphosphate is used in synthesis of Ubiquitin, Dolichol, Cholesterol

Shell formation in Mollusc Biomineralisation

Most accurate method of blood creatine estimation Jaffe method

STUDIES

Bioinformatics deals with Economics

Oldest and widely used bioinformatics database

Genbank, uniport, protein database

Bioinformatics is associated with Computer science, statistics, mathematics, engineering

Biotechnology is used for Viral vaccine production, To cure genetic disorder, Genetic crop, Gene production, Complete collection of gene copies of one organism

Study of structure and products of gene Genomics

Study of multiplication of proteins in disease process is called

Proteomics

Study of multiplication of proteins in a disease process Proteomics

Techniques used for protein expression proteomics study include

Gene array chips, two dimensional electrophoresis

BONDS

Drugs interact with their receptor sites by Ionic bonds

Strongest bond Electrostatic

Covalent bond Electrons have opposite spin

Weakest Bond Vander wall forces

Force NOT involved in antigen antibody reactions Covalent bond

NOT a force acting in enzyme substrate complex Vander walls

High energy phosphate bond (produce ATP on hydrolysis)

Creatine phosphate, Carbomyl phosphate. ATP,GTP,UTP, Co A derivatives

High energy compound on hydrolysis yield high standard free energy

Phosphoenolpyruvate

NOT a high energy bond substance CoA

BIOCHEMISTRY

www.medpgnotes.com

7 GENERAL BIOCHEMISTRY

Component making carbon bond of a molecule least polar

Carboxyl

PH AND BUFFERS

In a solution, concentration of H+ is 1*10^-6 moles/litre. pH of the solution

6

Number of pKa values possessed by Orthophosphoric acid

3

Buffering capacity of a buffer is maximum at pH equal to

pKa

High pKa lowers its Acidic nature A buffer that is most effective at a pH of about 4.5 Acetate buffer

Blood buffers Bicarbonate, Plasma proteins, Hemoglobin

Buffering capacity of Interstitial fluid is greatest by Bicarbonate

Most powerful extracellular buffer Bicarbonate Most important buffer in RBC H2Co3 + NaHCO3

Most important buffer in ECF Bicarbonate

Intracellular buffer Phosphate

ENERGY

Energy required for basal metabolism 1 kcal/hour/kg of body weight

Difference between reversible and irreversible reaction Work done

Entropy Measure of randomness in a system

Entropy in biological system does NOT increase because It is a open system

Largest reserve of energy in body stored as Adipose tissue

Adipose tissue lacks Glycerol 3 kinase Main source of energy derived from Glycogen

Specific dynamic action is Energy expanded on consumption of food

Best source of energy Lean meat

Energy emitted following absorption of EM radiation Phosphorescence

Heart at rest utilizes Fatty acid

Metabolism in brain Fatty acids are NOT utilized in starvation, Ketone bodies are used during starvation, 60% of total energy is obtained in resting state, Has no stored energy

Descending order of energy Fat > alcohol > carbohydrate

PATHYWAYS IN CYTOSOL AND MITOCHONDRIA

Creatine Phosphokinase is both Mitochondrial and Cytoplasmic

Pathway occurring both in mitochondria & cytosol Heme synthesis, Gluconeogenesis, Urea cycle

De novo fatty acid synthesis Cytosol

Glycogenesis occurs in Cytosol Glycolysis occur in Cytosol

Pathways occurring in mitochondria Beta oxidation of fatty acids, citric acid