Amino acids and Proteins

Information about Amino acids and Proteins

Published on August 11, 2014

Author: me33ra

Source: authorstream.com

Content

Amino acids and Proteins: Amino acids and Proteins Pooja Harikumar Animal Cell: Animal Cell Cell membrane controls passage of ions, molecules and water in and out of the cell. Cytoplasm gel-like substance enclosed within cytoplasm .Enzyme- catalyed reactions occur here. Mitochondrioa site of many redox reactions taking place. ATP (energy transffer molecule) is synthesised here. ‘’Power house of the cell’’. Ribosomes structures found in the cytoplasm that are site for protein synthesis Nuclues contains genetic material-DNA METABOLISM- sequence of linked chemical reactions that take place in the cell. Amino acids: Amino acids Amino acids are the monomer, the building block or proteins .It has a an alpha carbon that is linked to an amine group, a carboxyl group, hydrogen and an R group (side chain) Side chains: Side chains Type of side chain structure Non- polar Polar Electrically charged How amino acids behave indifferent environments: How amino acids behave indifferent environments Amino acids are linked together by peptide bonds: Amino acids are linked together by peptide bonds Peptides are chains of amino acids. Condensation reaction occurs . 1)Peptide bond is formed and a dipeptide is formed. When many amino acids are linked it becomes a polypeptide. Peptide linkage hold protiens together. 2)The amino acid is connected to the carboxyl group of the other. Another example-: Another example- And to write it down-: And to write it down- In a polypeptide chain: In a polypeptide chain Some Protein functions in the body.: Some Protein functions in the body . Enzymes - Eg: pepsin is a digestive enzyme. Transport - carrier proteins that move molecules from one place to another. Eg: haemoglobin that transports oxygen around the body. Contractile – responsible for muscle contraction and movement. Eg: myosin and actin. Structural - fibrous and stringy that provide support.Eg: Keratin - hair, nails feathers etc.. , collagen and elastin – support connective tissues like ligaments and tendons. Hormones - are messenger proteins which help to coordinate certain bodily activities. Functions are determined by the shapes of the protein Protein structures.: Protein structures . Primary Structure- The sequence of amino acids in the polypeptide chain . Secondary Structure - coiling or folding of a polypeptide chain. There are 2 types of secondary structures- 1) alpha ( α) helix 2) (β) pleated sheet Tertiary Structure - refers to the comprehensive 3-D structure of the polypeptide chain of a protein. This shape is stabilised by 4 types of bonds. Quartenary Structure- Ah we don’t need to study this. Primary structure: Primary structure In the primary structure of a protein: -Amino acids are numbered from the N terminal. a polypeptide chain is always synthesised from the N-terminal end to the C-terminal end . -determines the way that the protein can fold to form secondary and tertiary structures. -Held together by covalent bonds. -in the primary sequence are the positions of any cysteine residues, as these will determine the possible formation of di-sulfide bridges to stabilise the 3D-tertiary structure of the protein. Secondary structure: Secondary structure The alpha helix The beta pleated sheet Folding or coiling of a polypeptide results in the secondary structure The alpha helix: The alpha helix An α-helix is a coil of amino-acid residues on a polypeptide chain. This coil is held together by hydrogen bonds between the oxygen of C=O on top coil and the hydrogen of N-H on the bottom coil. So basically all the –NH and –CO groups are involved In hydrogen bond formation. Stability: A large number or hydrogen bonds in the same direction stabilises the structure. The side chains stick outside the helix. This structure resembles a coiled spring secured by hydrogen bonding. The beta pleated sheet: The beta pleated sheet is the second form of regular secondary structure in proteins. It is less common than the alpha helix . Hydrogen bonds are formed between –NH and –CO groups in a different polypeptide chain or different areas of the same polypeptide chain . Forming a generally twisted, pleated sheet. Tertiary Structure: Tertiary Structure R groups interacting There are several types of bonds and forces that hold a protein in its tertiary structure . 1) Disulfide bridges- covalent S-S bonds.(Usually found in proteins which function bodycell Eg : digestive enzymes) 2)Weak van der Waal’s forces. 3)Relatively weak hydrogen bonds 4)Ionic bonds maintained by a series of mainly non-covalent, intramolecular . I nteractions between the R-groups of the amino acids making the chain. PowerPoint Presentation: Disulfide bridges help maintaining the tertiary structure by ‘locking’ the polypeptide chains in place. it can be formed within same polypeptide chain or between different polypeptide chains. Van der Waal’s forces are formed when non-polar amino acid residues are close to one another. Stability due to these forces count. Hydrogen bonds are formed between polar side chains having hydrogen atoms attatched to the highly elecetronegative atoms like nitrogen or oxygen .(Between serine residues and threonine residues) Ionic bonds are formed between ionised acidic side chainsand ionised basic side chains. The formation of ionic bond depends on pH of the environment in which residues exist. Quaternary structure: Quaternary structure Haemoglobin - Human haemoglobin consists of two pairs of identical protein chains. These chains assemble together to form the functional, oxygen-carrying protein in our red blood cells. lets look at all the structures once more.: lets look at all the structures once more. Bonds each structure has :: Bonds each structure has : I guess that’s it : I guess that’s it  Thank you

Related presentations