We tend to ignore the biochemical reactions taking place in our body. This slight show will enable us to understand few of the pivotal reactions.

2. BY DR.SUKANYA
MOHANTY
1STYEAR MDS

3. WHAT IS METABOLISM?
DEFINITION
BIOENERGETICS
THERMODYNAMICS
CARBOHYDRATE METABOLISM
PROTEIN METABOLISM
ATP-ADP SYSTEM OF ENERGY EXCHANGE
FAT METABOLISM
CONCLUSION
BIBLIOGRAPHY

4. THE SUMTOTAL OF PHYSIO-CHEMICAL ACTIVITIES IS CALLED
“CELL OR INTERMEDIARY METABOLISM, AS EVERY CELLULAR
ACTIVITY INVOLVES CHEMICALTRANSFORMATION OF MATTER.
Reference from text book of modern zoology by DR. Rakesh Gupta

5. CELL METABOLISM HAS TWO ASPECTS
ANABOLISM
It is the constructive phase of
metabolism.
It occurs in the cytosol.
CATABOLISM
It is degrative phase of metabolism.
Its chief site is the mitochondria.

6. Thermodynamics tells us that every transformation of matter
(chemical transformation) is accompanied with energy conversion.
HENCE INTHIS CONTEXT METABOLISM IS DEFINEDAS
SUMTOTAL OF ALL ENERGY GAIN (CAPTURE) AND
RELEASE(UTILIZATION) PROCESSES IN A LIVING CELL.

8. All matter locks energy in the form of bonds between component
molecules and atoms. this energy is chemical energy.
The ultimate source of energy is in fact the light energy of sun rays
(solar energy).
Green plants absorb solar energy with the help of chlorophyll and
lock it into C-C or C-H bonds, synthesizing carbohydrates in process called
photosynthesis.
The green plants are producers of the matter used by organism
while non-green plants and animals are consumer.
SOURCE OF ENERGY:-

9. BIOLOGICAL ENERGY:-
Whenever matter is broken down,its chemical energy is released as heat.
nonbiological systems can utilize this heat directly in the performance of
work , as they are anisothermal.conversely biologic system are isothermal
These isothermal organism are of two types
POIKILOTHERMAL
Organism whose optimum
temperature is equal to environment.
HOMEOTHERMAL
Maintain fixed
body temperature.

10. ATP-ADP SYSTEM OF ENERGY EXCHANGE
IN 1929 LOHMANN, FISKEAND SUBBAROW published their discovery that
energy exchanger of all biological compounds are 2 phosphorylated
derivatives of adenosine monophosphate that is adenosine di
phosphate and adenosine tri phosphate.
 Terminal phosphate bonds one in AMP and 2ATP depicted by “~” instea
“-” are high energy bonds because these bind 2 ½ times more energy than
ordinary phosphate bond.

11. POWER HOUSES OF CELL FACTORY
Chief sites of catabolic breakdown of fuel compounds for
energy production and ATP production in cells are mitochondria.
thus mitochondria is called power houses or power plants of
cell factory.
Animals digest and obtain 3 main types of compounds – carbohydrates,
fats and protein which are therefore called their nutrients.
USESOF BIOLOGICAL ENERGY:-
Biosynthesis
Secretion
Mechanical work
Active transport

12. IT IS DIVISIBLE INTO 5 ASPECTS
GLYCOGENESIS GLYCOGENOLYSIS
ANABOLISM AND
LIPOGENESIS
GLUCONEOGENESIS
CATABOLIC
BREAKDOWN

18. GLUCONEOGENESIS
When diet is insufficient of
carbohydrates, glucose or glycogen
is formed from noncarbohydrate
compounds, principally amino acids
and glycerol of triglycerides , this is
called gluconeogenesis.
It occurs in the liver.

19. CATABOLISM
ENERGY YIELDING OXIDATIVE BREAKDOWN OF GLUCOSE AND
OTHER FUEL SUBSTANCE IN A COMPLEX PROCESS CALLED
CATABOLISM OR CELLULAR RESPIRATION.
2 TYPES
ANAEROBIC AEROBIC
Anaerobes produce energy only
by this pathway due to absence of
Oxygen and this process is called sugar
Fermentation.
It occurs in the cytoplasm
The organism using oxygen
are called aerobes.

23. FATE OF PYRUVATE

25. AEROBIC OXIDATION
In this system pyruvic acid (obtained from glycolysis) is not used as an
electron acceptor to generate NAD+ instead NADH.H is reoxidized to
NAD+ with the help of oxygen and pyruvic acid is reoxidized yielding 20
times more energy than glycolysis.

26. THE OXIDATION IS ACCOMPLISHED BY 4 PROCESS
CONVERSION OF
PYRUVIC ACID
TO ACETYL COA
KREB
CYCLE
ELECTRON TRANSPORT SYSTEM
OXIDATIVE
PHOSPHOR
-YLATION

27. CONVERSION OF PYRUVIC ACID TO ACETYL CO ENZYM
This is mediated by enzyme named Pyruvate Dehydrogenase, that
converts pyruvic acid to Acetyl co A.
Occurs within the mitochondria.
Acetyl coA is a high energy compound and it plays a
pivotal role in aerobic oxidation of all energy producing
organic compounds.

29. REGULATION OF PDH:-
Cofactors and coenzyme used by pyruvate dehydrogenase include
Thiamine pyrophosphate from vitamin thiamine.
FAD(H)from riboflavin
NAD(H) from niacin
Lipoic acid
Coenzyme A

31. KREBS CYCLE
The acetyl group of acetyl co a is now completely degraded stepwise
into carbon and hydrogen atoms in mitochondria by cyclic sequence of
eight steps.

32. ELECTRON TRANSPORT SYSTEM

33. OXIDATIVE PHOSPHORYLATION
At 3 sites (complexes1,3 and 4)n along a respiratory chain each electron
pair loses as much of its free energy that each site a phosphate molecule
binds with an ADP Forming high energy ATP. Since oxidation and
phosphorylation occur simultaneously this reaction is termed as Oxidativ
Phosphorylation.

39. Proteins are the most abundant (75% by dry weight) constituent of
the body.
It is required for
Architecture
Growth
Repair
Contraction
Movements
Metabolic reactions
Transport of
material
Defense
Synthesis of protein is major anabolic process.

40. CELLULAR METABOLISM OF PROTEIN HAS 2
IMPORTANT ASPECTS:-
PRTOEIN
SYNTHESIS
CATBOLISM
OF PROTEINS

41. WHAT IS DNA AND RNA???
Cells have two types of nucleic acids DNA and RNA.
DNA:-
It is double helical polynucleotide composed of phosphate group,
deoxyribose sugar and a nitrogenous base, which may be adenine,
Guanine, cytosine or thymine.
DNA is present in the nucleus.
DNA contains coded information of hereditary protein types.

42. RNA:-
It is usually single polynucleotide chains whose monomers consist of
Phosphate group, ribose sugar and a nitrogenous base which may be
Adenine, guanine, cytosine and uracil.
RNA occurs both in the cytosol and nucleus.
RNA monitors the protein synthesis according to coded information.
There are three categories of RNA molecules in all cells namely
ribosomal RNA, (rRNA), transfer RNA(tRNA) and messenger RNA(mRNA).

43. TYPES OF RNA
Messenger RNA molecules are long single RNA strands that are
suspended in the cytoplasm.
They contain codons that are exactly complementary to code
triplets of DNA gene.
MESSENGER RNA

44. Transfers Amino acid to protein molecules as the protein is being
synthesized.
Each type of transfer RNA combines with 1 of the 20 amino acid that
has to be incorporated into proteins.
The transfer RNA acts as a carrier to transport its specific type of
amino acid to the ribosomes.
 It has a typical clover leaf like appearance.
TRANSFER RNA

45. RIBOSOMAL RNA
It constitutes about 60% of the ribosome, the remainder is protein.
Ribosomal RNA consists of single strand twisted upon itself at some
regions.

46. CODON
A codon designates an amino acid and amino acid may have more
than one codon acid.
There are 20 types of amino acid, and 64 possible codon.
One of the codons represent the start of manufacturing protein molecu
AUG(methionine).
The three codon that stops protein synthesis are UAA, UAG and
UGA.

47. THE CENTRAL DOGMA OF LIFE

48. TRANSCRIPTION
Copying of genetic material from DNA to RNA is called Transcription.
WHY TRANSCRIPTION REQUIRED?
DNA has the genetic code for protein that needs to be, but proteins
are made by the ribosomes and ribosomes are outside the nucleus in
the cytoplasm.
DNA is too large to leave the nucleus(double stranded), RNA can leave
the nucleus(single stranded).

49. STEPS OF TRANSCRIPTION
INITIATION
RNA polymerase binds to DNA at specific sequence of nucleotides
called promotor.
The promotor contains initiation site where transcription begins.
RNA polymerase then unwinds the DNA.
ELONGATION
Only one of the unwound DNA acts as the template for RNA synthesis.
RNA polymerase adds nucleotides to 3’ end and mRNA is synthesized
from 5’to 3’ end.
Free ribonucleotides triphosphates from the cytoplasm are paired with
complementary strand on DNA template.
RNA polymerase joins the ribonucleoside triphosphate to form mRNA.

50. TERMINATION
Termination takes place by two mechanism:-
In the first the termination signal appears to be recognized by DNA.
The second type of termination signal involves an additional protein
called as rho.

51. TRANSLATION
The main steps in translation are:-
Activation of amino acids
Transfer of amino acid to tRNA
Initiation of protein synthesis
Elongation of polypeptide chain
Chain termination
Translation is RNA directed synthesis of a polypeptide chain.

52. ACTIVATION OF AMINO ACIDS
The first step in translation is activation of amino acids.
The 20 amino acids found in the proteins are screened to eliminate
D-isomers.
Only L-amino acids take part in protein synthesis.

53. TRANSFER OF AMINO ACID TO t-RNA
The transfer of activated amino acid to t-RNA is specific.
The t-RNA is named after the amino acid for which it is specific, example
Isoleucine, valine are designated as tRNAileu and tRNAval, respectively.

54. INITIATION OF SYNTHESIS
The initiation of protein synthesis requires certain initiation factors
(IF).
The first step in protein synthesis is formation of the initiation
complex.
This complex consists of mRNA, 30s ribosomal subunit, t-RNA
attached with amino acid, GTP and three initiation factors (IF-1, IF-2
and IF-3).

55. Ribosome
 The ribosome has three binding sites for tRNA
 The P site
 The A site
 The E site
E P A
P site (Peptidyl-tRNA
binding site)
E site
(Exit site)
mRNA
binding site
A site (Aminoacyl-
tRNA binding site)
Large
subunit
Small
subunit

56. ELONGATION OF THE POLYPEPTIDE CHAIN
Ribosome move down the messenger RNA adding new amino acid
to the growing polypeptide chain.
The ribosomes read the sequential ‘codon messages’ as if reading a
tape and help in proper orientation of tRNA on mRNA template.
Under the influence of enzyme peptidyl transferase peptide bonds are
formed between successive amino acid thus adding progressively to the
growing polypetide chain.

57. TERMINATION OF TRANSLATION
The process of synthesis of polypeptide chain continues till a
terminating or stop codon on mRNA slides past the ribosome.
The codons that terminate protein synthesis are UAA, UAG and
UGA.
As the protein synthesis stops, the proteins are released into the
cytoplasm.

60. CATABOLISM OF AMINO ACIDS
AA CARBON
AMMONIA
HIGHLY TOXIC
Catabolism is reviewed into two parts disposal of amino group and
disposal of carbon skeleton.

61. Fuels burned by the body include sugar, fatty acids and amino acids.
These three forms are interconverted via separate synthetic and
degradative pathways, thus allowing them to be stored and mobilized
independently.
Since the proteins are widely distributed in living matter, understanding
the basic mechanism of protein synthesis is pivotal.

62. CELL BIOLOGY BY C.B. POWAR
MODERN ZOOLOGY BY DR.RAKESH GUPTA
NBDE PART 1 LECTURE NOTES BY KAPLAN MEDICAL