They contain C, H, O, N In some P, S, Mg or Fe are present Proteins are the most diverse biological molecules. They can either function as structral or functional. The building blocks of proteins are amino acids. PROTEINS

The Structure and Function of Proteins An amino acid consists of 1.An amino group ( -NH 2 ) 2. A carboxyl group ( -COOH) 3. A simple hydrogen atom (-H) 4. Radical group (R) Proteins are polymers made up of amino acids.

All amino acids have the same general formula. The part that makes them different from each other is their radical group (R). The Structure and Function of Proteins

Synthesis of dipeptide and polypeptide The amino acids are joined together by peptide bonds. A peptid ebond is formed between the amino part of one amino acid and carboxyl part of another amino acid. This is also a dehydration synthesis. +H 2 O peptide bond Formation of polypeptide chain n (amino acids) Polypeptide + (n-1) H 2 O Dehydration Synthesis ATP enzyme polypeptide + (n-1) H 2 O n (amino acid) Hydrolysis

animals cannot synthesize 8 essential a.a, plants can synthesize all of them. there are 20 different a.a enormous variety of protein can be produced by the different combinations of 20 a.a The Structure and Function of Proteins the number of different proteins that can be synthesized is almost endless. This is because; Proteins differ in number of amino acids they contain Proteins differ in the types of amino acids they contain Proteins differ in sequence in which amino acids are bonded

‘ Why are the two a.a different from eachother?’ Because radical groups (R) are different in each amino acid ‘What makes the difference between two proteins?’ Sequence of a.a Number of a.a Types of a.a

The differences in the sequence of amino acids make different proteins. These proteins may have primary, secondary, tertiary and quaternary structures. The Structure and Function of Proteins Protein Structures

Secondary proteins consist of single polypeptide chain. H-bonding is seen in this structure. Ex: actin, myosin, keratin Primary proteins consist of single polypeptide chain They are not functional They take part in secondary, tertiary and quaternary structure.

Tertiary proteins have the shape resulting from R-group interactions. Quaternary proteins incorporate two or more polypeptide chains. Globular, fiber like proteins are in this group. Ex: Hemoglobin

 The function of a protein is result of its 3-D structure or confirmation in turn, is determined by amino acid sequence and the reactions that occur between neighboring amino acids and those that are far apart in the sequence. If its 3-D structure is disturbed, the protein ceases (loses) it’s function. It is denaturated.  If you give heat to protein (egg), it loses its structure and it is denaturated. This process is called

Types of Proteins PROTEINS ACCORDING TO THE STRUCTURE Simple ProteinsComplex Proteins These proteins form only amino acids when hydrolyzed. Ex: albumin, globulin,histones These proteins form amino acids and other substances when hydrolyzed. Ex:glycoproteins, lipoproteins, nucleoproteins, phosphoproteins glikoprotein

Types of Proteins PROTEINS ACCORDING TO THEIR SHAPE Fibrous ProteinsGlobular Proteins are long, chain like proteins very resistant to stretching form the flexible parts of body are sphere shaped are found in the cytoplasm water soluble, metabolic proteins

THE IMPORTANCE OF PROTEINS STRUCTURE: Proteins are building and binding materials of living things. ex: nail, hair, cartilage, muscle CATALYSIS: Enzymes that control the rate of chemical reactions are protein. CONTROL: Hormones are chemical substances that have specific effects on certain organs. Some hormones are proteins. Ex: Insulin and Glucagon TRANSPORT: Oxygen is carried from lungs to tissues by a protein called hemoglobin in red blood cells. There are proteins in the cell membrane.

MOVEMENT: Proteins alike actin and myosin are found in the muscles and are responsible for the movement of muscles. PROTECTION: Antibodies are proteins that are synthesized in response to foreign substances and cells such as bacteria. STORAGE: Some proteins like ferritin store iron in liver, spleen and bone marrow. BUFFERING: Proteins act as buffers in blood and tissues.

Organic molecule Subunit Element Chemical Bond (monomer) Carbohydratemonosaccharide C, H, O, some N  Chitin glycoside Lipidsfatty acids+ glycerol C, H, O Some(P, N) phospholipid ester Proteinsamino acids C, H, O, N (some P, S, Mg, Fe) peptide

Usage of Organic Compounds by Cells CARBOHYDRATES: are the first energy source, breaking down of carbohydrates is easy. LIPIDS: they give out more energy than carbohydrates however breaking down of lipids is difficult. PROTEINS: they are the last energy source of cell because organisms cannot deposite protein for energy yield. They are found in the structure of cell and enzymes. That’s why they are used as last energy source. (In a long period of hunger, they are used)