#12. Proteins - amino acids, peptid bonds
Biology

#12. Proteins - amino acids, peptid bonds


Proteins are large molecules made of long chains of amino acids.






1. Amino acids

All proteins have the same basic structure. They consist of an Amino Group (NH2), an Carboxyl group (COOH), and a Carbon in the middle which bonds with a Hydrogen atom and an 'R' group, which is specific to individual amino acids.



There are 20 naturally occurring 'R' groups, making amino acids neutral, acidic, alkaline, aromatic (has a ring structure) or sulphur-containing). The 20 R groups corresponds to 20 different amino acids. Each different amino acid has a specific name. For example, Alanine's 'R' group consists of CH3.

2. Peptid bonds

a. Condensation reaction:
                   2 amino acids are joined by a peptide bond ---> dipeptide + H2O.




    b. Hydrolysis reaction: 
    Dipeptides are split into 2 amino acids by breaking the peptide bond using a molecule of H20. 




     Syllabus 2015

    (f) describe the structure of an amino acid and the formation and breakage of a peptide bond;




    Syllabus 2016 

    An understanding of protein structure and how it is related to function  is central  to many aspects of biology, such  as enzymes, antibodies and muscle contraction.

    Globular and fibrous proteins play important roles in biological processes such  as the transport of gases and providing support for tissues.

    a)   describe the structure of an amino  acid and the formation and breakage of a peptide bond






    - Amino Acid Activation
    Codons of an mRNA molecule contain genetic messages that are carried by the mRNA and they need to be translated to form the corresponding sequence of amino acids that will form the polypeptide chain and subsequently the protein. The tRNA transfers amino...

    - Translation
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    - #13. Protein - Primary, Secondary, Tertiary And Quaternary Structure
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    - #7.2 Biological Molecules - Syllabus 2016
    2.1    Testing for biological molecules 2.2    Carbohydrates and lipids 2.3    Proteins and water This section introduces carbohydrates, proteins and lipids: organic molecules that  are important in cells. Nucleic...

    - Polypeptide
    Term: polypeptideLiterally meaning: ?several peptides?Origin: Greek????-/poly-(=many, several)????????/peptidio(=peptid) a low weight polymer  composed of two (dipeptide)  or more amino acids joined by peptide bonds  consisting...



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