protein as a biomolecule
TRANSCRIPT
Tuesday, May 2, 2023 Pranabjyoti Das 1
ARUNODOI JUNIOR COLLEGE
Where The Sun Never Sets !
Author
BIOMOLECULESProtein
Structure & Functions
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What is Protein ?Proteins are some important biomolecules
found in all living cells. Proteins are some polymers of Amino Acids.Proteins are found in our body as Muscles,
Enzymes, Hormones, Antibodies and many more.
We get some proteins into our body as food like Meat, Fish, Eggs, Soya etc.
Some proteins can be synthesized by the Ribosome of our cells.
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Some Proteins under Electron Microscope
AntibodyMyoglobin
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Give examples of proteins that are important to the structure of
organisms….Some proteins are important to the structure of organisms
Question For You:
Our hairSpider silk
Fibers of Tendons and Ligaments
Our Muscles etc.
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Name some Proteins that serve the following specific functions….
For You Again
Name a Protein that carry oxygen in our body.Ans : Haemoglobin
Name a Protein that provides us with immunity.
Ans : AntibodyName a Protein that serves as
enzyme.Ans : Pepsin, Renin, Trypsin etc
PROTEIN STRUCTURE
An α-amino acid. The CαH atom is omitted in the diagram.
CO-R-N rule
Two amino acids Bond angles for ψ and ω
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Proteins are made of some Amino Acids
Amino Acids are biologically important organic compounds containing one Amino group (-NH2), one
Carboxyl group (-COOH) and a side chain with one R group.
Amino Acid
An Amino Acid Has…
20 different Amino Acids make up all
our Proteins
Central carbon atom
An amino groupA carboxyl group
An R-group
The R-group varies from one amino acid to another
A hydrogen atom
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Amino Acids Are Of Two Types
Non-Essential Amino Acids :
The Amino Acids which can be synthesized in our body by Ribosomes. Example: Alanine, Glutamate, Proline etc. Essential Amino Acids:
The Amino Acids which are never synthesuzed in our body and we need to get them in our food. Example: Methionine, Valine, Leucine etc.
There are only 20 Amino Acids which link together with each other by Peptide Bond to form Protein
Structure of Amino Acid
Amino acids have an amino group and a carboxyl group
Both groups are covalently bonded to the center carbon atom, called the alpha carbon.
Bonded to the alpha carbon is a hydrogen atom and a chemical group called the ‘R group’.
The amino acid type differs depending on the structure of the R group.
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Amino Acids are linked to form Peptide Bond
Two amino acids join together by a condensation reaction
Water molecule removed is removed when a carboxyl group binds to the nearby amino-group
Resulting covalent linkage is called a peptide bond.
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Formation of Peptide Bond
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Proteins are biochemical compounds consisting of
one or more polypeptide chains typically folded into
a globular or fibrous form in a biologically functional way.
Proteins were first described by the Dutch chemist Gerardus Johannes Mulder and named by the Swedish chemist Jöns Jacob Berzelius in 1838. Early nutritional scientists such as the German Carl von Voit said
that protein was the most important nutrient for maintaining the structure of the body, because it was
generally believed that "flesh makes flesh.
More About Proteins..
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Primary Structure of Protein
The primary structure refers to amino acid sequence of the polypeptide chain. The
primary structure is held together by covalent or peptide bonds, which are
made during the process of protein biosynthesis or translation. The two ends of the polypeptide chain are referred to as the
carboxyl terminus (C-terminus) and the amino terminus (N-terminus) based on the nature of the free group on each extremity. Counting of residues always starts at the N-terminal end (NH2-group), which is the end where the amino group is not involved in a
peptide bond.
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Secondary Structure of Protein
These secondary structures are defined by
patterns of hydrogen bonds between the main-
chain peptide groups. They have a regular geometry,
being constrained to specific values of the
dihedral angles ψ and φ on the Ramachandran plot. Both the alpha helix and
the beta-sheet represent a way of saturating all the
hydrogen bond donors and acceptors in the peptide
backbone.
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Tertiary Structure of ProteinProtein tertiary structure is the 3D shape of a protein. The tertiary structure will have a single polypeptide chain as "backbone" with
one or more protein secondary structures. Amino acid side chains may interact and bond in a number of ways. The
interactions and bonds of side chains within a particular protein determine its tertiary structure.
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Quaternary Structure of Protein
Many proteins are made up of multiple polypeptide
chains called as referred to as protein subunits.
The quaternary structure refers to how these protein subunits
interact with each other and arrange themselves to form a larger aggregate protein complex. The final shape of the protein complex is once again stabilized by various
interactions, including hydrogen-bonding,
disulfide-bridges and salt bridges.
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Formation of Polypeptide Chain
Polypeptide chain consists of a bunch of different amino acids linked together.
One after another, the amino acids are linked together with each other by Peptide bond.
Between 2 Amino Acids a Monopeptide , between 3 Amino Acids a Dipeptide and so on
When many Amino Acids are held together, it form the Polypeptide chain
Function of ProteinsFunctions of proteins
can be interchangeable with functions of
polypeptides
Type of Protein
Function
Structural Proteins
Support
Storage Proteins
Storage of AA
Transport Proteins
Transport substances
Hormonal Proteins
Coordination
Receptor Proteins
Response to stimuli
Contractile Movement
Defensive Proteins
Disease protection
Enzymatic Proteins
Catalytic action
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What are the importance of proteins ?They have a structural function and serve as cell membrane protein, cytoskeleton protein, connective tissue proteins etc
They have an enzymatic function to catalyze biochemical reactions
They carry out a transportation function to carry oxygen in our body
They provide us immunity in the form of Antibody
They help us in our movement by contractile function of muscles
Protein is a body building food for us
And many more…
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Questions For You1. What unit are proteins composed of ?
2. How many amino acids are known to form proteins?
3. What is the bond between two amino acids called ?
4. What is the primary structure of a protein ?
5. What are Non-essential Amino Acids ?
6. Who coined the term Protein ?
7. What is a polypeptide chain ?
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