What is Protein? Protein is a biologically functional molecule that consists of one or more polypeptides or Proteins are building blocks of Amino acids Polypeptides are unbranched polymers built from the same set of amino acids

1. SHARANABASAPPA M GANGANALLI
ID. NO. 2018-21-046
Ist Ph.D. Depart. Entomology
WELCOME

2. Protein synthesis, Structure and types
of Nucleic acid
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3. Contents
1. What is protein?
2. Protein synthesis
3. Protein Structure
4. Functions of proteins
5. Disorder
6. Nucleic acids
7. Differences between DNA & RNA
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4. What is Protein?
• Protein is a biologically functional molecule
that consists of one or more polypeptides
or
• Proteins are building blocks of Amino acids
• Polypeptides are unbranched polymers built
from the same set of amino acids
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5. Protein synthesis or Central dogma
• The two main processes involved in protein synthesis are
1. Formation of mRNA from DNA (transcription)
2. Conversion by tRNA to protein at the ribosome (translation)
• Transcription takes place in the nucleus, while translation
takes place in the cytoplasm
• Genetic information is transcribed to form mRNA
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6. Protein structure
• Primary structure consists of its unique
sequence of amino acids
• Secondary structure, found in most proteins,
consists of coils and folds in the polypeptide
chain
• Tertiary structure is determined by interactions
among various side chains (R groups)
• Quaternary structure results when a protein
consists of multiple polypeptide chains
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7. 1. Primary structure
• Primary structure consists of its
unique sequence of amino acids
• Primary structure is
determined by inherited
genetic information
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8. 2. Secondary structure
• The coils and folds of
secondary structure result
from hydrogen bonds
between polypeptide
backbone
• Typical secondary structures
1. Coil called an  helix
2. Folded structure is  pleated
sheet
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9. 3. Tertiary structure
• Interactions between R groups include, ionic bonds and
strong covalent bonds called disulfide bridges in protein’s
structure.
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10. 4. Quaternary structure
• Quaternary structure results when two or more
polypeptide chains form one macromolecule
Ex: Collagen is a fibrous protein consisting of three
polypeptides coiled like a rope
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11. ………Quaternary structures
• Ex: Hemoglobin is a
globular protein
consisting of four
polypeptides:
1. Two alpha
2. Two beta chains
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12.  Protein structure revisited
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13. Functions of proteins
Type of
Function
Example Function
Enzymes amylase Promotes breakdown of starch
Hormones insulin Regulates blood sugar levels
Structural keratin Hair, wool, nails, horns, hoofs, etc.
Transport hemoglobin Carries oxygen in blood
Immune
defense
antibodies Rid the body of foreign proteins
Contractile actin Contracting fibers in muscles
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14. Disorder
• A slight change in primary structure can affect a
protein’s structure and causes Sickle-cell disease
• Sickle-cell disease, an inherited blood disorder, results
from a single amino acid substitution in the protein
hemoglobin
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15. Nucleic acids
• Nucleic acids are molecules that store information for
cellular growth and reproduction
Two types of nucleic acids:
1. Deoxyribonucleic acid (DNA)
2. Ribonucleic acid (RNA)
• These are polymers consisting of long chains of monomers
called nucleotides
Nucleotide
1. Nitrogenous base
2. Pentose sugar
3. Phosphate group
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16. Sugar-phosphate backbone
5 end
5C
3C
5C
3C
3 end
Polynucleotide, or nucleic acid
(b) Nucleotide
Phosphate
group Sugar
(pentose)
Nucleoside
Nitrogenous
base
5C
3C
1C

17. Nitrogen bases
1. Purines: adenine (A) and guanine
(G)
2. Pyrimidines: cytosine (C),
thymine (T) and Uracil (U)
Pentose sugars:
1. Ribose
2. Deoxyribose
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18. Names of nucleosides and nucleotides
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19. Differences between DNA & RNA
DNA:
• Deoxyribose sugar
• Contains thymine (T)
A-T and C-G
• Double-stranded
RNA:
• Ribose sugar
• Contains uracil (U)
instead of thymine
A-U and C-G
• Single strand
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