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Food Biotechnology (BIT-313) Lecture 3

Introduction to proteins and nucleic acids

Basic biochemcial structure of these molecules

Important functions of these biomolecules in living cells

Industrial significance of these biomolecules

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Understand the significance of proteins and nucleic acids in food

Understand basic structure and function of some commonly used proteins and NAs in food industry

Understand the role of these molecules in important metabolic pathways in the food industry

Section III

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Most abundant macromolecules found in

living cells

30-70% cell dry weight

Essential to all life forms

High molecular weigth heteropolymers

Made up of different amino acids (AAs)

Roles in Bioprocesses

◦ Cell Signalling

◦ Cell Adhesion

◦ Immune Response

Structural and Mechanical Roles

◦ Muscles and connective tissues

◦ Cell walls in Plants

◦ Other structures in animals

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Functions

Structure

Catalysis

Movement

Transport

Hormones

Protection

Storage

Regulation

Animals

•Dairy Products

•Fish

•Meat

Botanical

•Pulses

•Seeds

•Green Vegetable

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Willams, P.A & Phillips, G.O. (2011)

High Biological Value (HBV): contain all essential amino acids

Low Biological Value (LBV) :do not contain all essential amino acids (must be supplemented by other sources)

HBV Protein Foods LBV Protein Foods

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C, H, O , P, N, S

20 amino acids

Primary amine group and carboxylic group attached to

α-carbon

R group is different in every amino acid (characteristics

of AA)

Amphoteric in nature

Alkaline Part

Acidic Part

N-terminus

C-terminus

Amino acids join together to form a Peptide chain

Free OH of one AA combines with the NH2 of the next AA

Protein size ranges between 15-10,000 AA

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Primary

Secondary

Tertiary

Quaternary

Simple Classification ◦ Fibrous (Structural roles)

◦ Globular (Functional roles)

Peptide Linkage

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α- helix β- pleated sheets

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Linear proteins structural roles long fibers (collagen, cartilage, keratin)

Globular proteins dynamic/ functional role ◦ Soluble in aqueous environment

◦ Transport processes

◦ Enzymes

Food Cosmetics Pharmaceutical

Medicines Adhesives Packaging

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Food ingredients

Food additives

Assignment 1

Section IV

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Long, thin, fibrous molecule

DNA – part of chromosomes

Molecular weight upto 109

DNA and RNA polymers of

neclotides

Monomer of DNA and RNA

Nitrogen base

5-carbon sugar ?

Phosphate group

5 different types of bases (Purines A,G; Pyrimidines C,T,U)

Purine Pyrimidine

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Purine

Ribose

Purine

Ribose

Phosphate

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Hydrogen bonding between

DNA antiparallel strands

Purines (A,G) Pyrimidines (C,T)

(A –T)(G-C) pairing

5’ and 3’ running in opposite

directions

Charged phosphate group on

the outside (Increase solubility)

3’ OH of one AMP molecule reacts with phosphate on 5’ C of another AMP molecule

In DNA, H-bonding between N bases

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Two main functions

◦ Generation of new DNA (Replication)

◦ Protein synthesis via RNA

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Single random coil

Purines (A,G), Pyrimidines (C,U)

Three main types of RNA in cells ◦ rRNA( ̴70%)

◦ tRNA (15%)

◦ mRNA (5%)

Important role in protein synthesis

Nucleic Acid rich foods

• Fish (salmon, sardine, herring)

• Nuts, wheat germ, oats

• Onion, spinach, asparagus

• Animal meats & eggs

Nutrients that aid DNA/RNA synthesis

• Folic acid, B vitmains, riboflavin, biotin (eggs), vitamin C

• Zinc, Magnesium, Chromium, Selenium

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Cellular regeneration Slow aging

Improved immune system

Purine and pyrimidine content of foods

Metabolic disorders ◦ Gout (uric acid accumulation)