The document discusses protein synthesis and enzymes, explaining their roles as essential components of human tissues and as biological catalysts. Key processes include transcription, where DNA is transcribed to RNA, and translation, where RNA is decoded to form proteins, involving ribosomes and transfer RNA (tRNA). Additionally, the document details enzyme characteristics, including their structure, mechanisms of action, and factors affecting reaction velocity.

1. Protein Synthesis, Enzymes & Their
Characteristics
Group 5#
MPhil Animal Nutrition
Group Members :-
• Sarmad Jamshaid
• Mehmood Ali
• Noman Ahmed
• Muhammad Abid Manzoor
• Muhammad Hassnat Afzal
• Waleed Hassan
• Adeel Sajid

2. Contents
•Introduction
•Function of Ribosomes
•Transcription
•Translation
•Functions of Proteins
•Different Protein Sources (Diet)
•Enzymes and characteristics

3. Introduction
• Proteins are large, complex molecule that are essential
components of all human tissues (e.g. blood, bones, hormones,
enzymes and antibodies)
• Proteins are macromolecules composed of amino acids that are
called “building blocks”

4. Types of Amino acids
•There are twenty different amino acids.
•We require all of them to make different proteins through
out the body.
•Amino acids are classified as essential or non essential.
•Eleven of the amino acids are considered non essential
because of the body can synthesis them through
transamination.

5. List of Different amino acids
•However nine of the amino acids are called essential
because we cannot synthesis them either at all or in
sufficient amount.
•They must be obtained from diet.

6. Introduction to Ribosomes:
• Proteins are manufactured by the ribosomes
• Ribosomes is complex molecular organelle found inside the
living cell.
• It produce protein from amino acids during a process of
translation.
• Prokaryotes have 70S ribosomes while eukaryotes have 80S
ribosomes
• Around 62% ribosomes are comprised of RNA while rest is
protein.

7. SYNTHESIS OF PROTEINS
Step 1: Transcription

8. Transcription :
• DNA transcription is a process that involves transcribing
genetic information from DNA to RNA.
• The transcribed DNA message, or RNA transcript, is used to
produce proteins.
• DNA is too large to leave the nucleus (double stranded), but
RNA can leave the nucleus (single stranded).

9. How DNA Transcription Works
•It consists of four nucleotide bases that are paired together
to give its double helical shape.
•These bases are: adenine (A), guanine (G)
(Purines) cytosine (C), and thymine (T) (Pyrimidines).
Adenine pairs with thymine (A-T) and cytosine pairs with
guanine (C-G).
•Nucleotide base sequences are the genetic code or
instructions for protein synthesis.

10. Three main steps are involved in Transcription
•Initiation
DNA is transcribed by an enzyme called RNA polymerase.
•Specific nucleotide sequences tell RNA polymerase where
to begin and where to end.
•RNA polymerase attaches to the DNA at a specific area
called the promoter region.
•The DNA in the promoter region contains specific
sequences that allow RNA polymerase to bind to the DNA.

11. Elongation:
•Certain enzymes called transcription factors unwind the
DNA strand and allow RNA polymerase to transcribe.
• Only a single strand of DNA into a single stranded RNA
polymer called messenger RNA (mRNA).
•The strand that serves as the template is called the antisense
strand.
•RNA contains the nucleotides adenine, guanine, cytosine,
and uracil (U). When RNA polymerase transcribes the
DNA, guanine pairs with cytosine (G-C) and adenine pairs
with uracil (A-U).

12. Termination:
•RNA polymerase moves along the DNA until it reaches a
terminator sequence.
•At that point, RNA polymerase releases the mRNA
polymer and detaches from the DNA.

14. Translation:
• Decoding of mRNA into a protein is called Translation.
• Transfer RNA (tRNA) carries amino acids from the
cytoplasm to the ribosome.
• mRNA must cross the nuclear membrane to reach the
cytoplasm in eukaryotic cells.
• A series of three adjacent bases in mRNA molecule
codes for a specific amino acid called a codon.

15. Continued…
• Each tRNA codes for different amino acids.
• mRNA carrying the DNA instructions and tRNA carrying
amino acids meet in the ribosomes.
Amino acid
Anticodon

17. Polypeptide = Protein

18. Protein make all living materials

19. Function of proteins:
• Help fight disease
• Build new body tissue
• Enzymes used for digestion and other chemical reactions are
proteins (Enzymes speed up the rate of a reaction)
• Component of all cell membranes

20. Sources of Proteins:
• Proteins we eat are broken down into individual amino acids.
• They simply rearranged into new proteins according to the
needs and directions of our DNA.

21. Enzymes

22. Overview
Biological catalysts that speed up chemical
reactions
• Protein in nature
• Catalytic behaviour of any enzyme depends upon its structure.
• Most enzymes are three dimensional globular Structure like primary,
secondary, tertiary or quaternary
• They speed up chemical reaction by lowering activation energy.
• Their presence does not affect nature and properties of end product.
• Highly specific in their action that each enzyme can catalyze one kind of
substrate.

23. Structure
• Active site is a region on the surface of an enzyme.
• Substrate will bind and catalyze a chemical reaction.
• Occupy less than 5% of surface of enzyme
• Active sites have very specific shape
• Change in shape of protein affects the shape of active sites and
function of enzymes.

24. Active Sites
Active Site Catalytic Site
It chooses the substrate and
binds it to the active site
It performs catalytic function
of enzyme

25. Cofactors
• Enzymes have non protein molecule which is called cofactor
• It carries out chemical reactions
• Without cofactor, protein is not active and called Apoenzyme
• Complete complex of protein with all molecules and components
attached are called Holoenzymes.
• Two types
1 Organic (Zn)
2 Inorganic ( Pyridoxal Phosphate)

26. Cofactors
Inorganic
Organic
Prosthetic
Group
Coenzyme
Tightly bound organic
Cofactor like flavin
Loosely attached
organic cofactor like
NAD+

27. Mechanism of enzyme action
The enzymatic reactions takes place by binding of
the substrate with the active site of the enzyme
molecule by several weak bonds.
E + S ‹--------› ES --------› E + P
Formation of ES complex is the first step in the
enzyme catalyzed reaction then ES complex is
subsequently converted to product and free
enzyme.

28. "Lock and key" or Template model
Proposed by Emil Fischer
It states that enzymes have rigid active sites
There is no change in the shape of active sites before and after chemical
reaction

29. Induced-fit model

30. e.g. H2O2
e.g. O2 + H2O
Progress of Reaction

31. Factors affecting reaction velocity
Temperature
Hydrogen ion concentration (pH)
Substrate concentration
Enzyme concentration

32. Effect of Temperature
Temperature(oC)
Reaction
Velocity
(v0)

33. Effect of pH
Reaction
Velocity
(v0)
pH
Pepsin
Trypsin
q r

34. Rate of the reaction or velocity is directly
propostional to the Enzyme Concentration
when sufficient substrate is present.

35. Effect of Substrate Concentration
Substrate Concentration/arbitrary Units
Reaction
Velocity
(v0)

36. Enzyme Inhibiton
Any substance that can diminish the velocity
of an enzyme catalyzed
These include drugs, antibiotics, poisons, and
anti-metabolites.
Useful in understanding the sequence of
enzyme catalyzed reactions, metabolic
regulation, studying the mechanism of cell
toxicity produced by toxicants.
Forms the basis of drug designing.