Protein Structure Assignment

Proteins Protein Structure Draw the basic structure of a generalised amino acid Outline the structural organisation of a polypeptide chain (monomer → polymer) Amino acids are joined via condensation reactions to form dipeptides (a water molecule is produced) ………………………………………………………………………………………………………………………………………………….......... The covalent bond that connects amino acids together in a polypeptide chain is called a peptide bond ………………………………………………………………………………………………………………………………………………….......... Polypeptide synthesis occurs at the ribosome via the process of translation ………………………………………………………………………………………………………………………………………………….......... Draw the basic structure of a generalised dipeptide Identify the number of different amino acids present in nature and how they are distinctive There are 20 different amino acids present within nature ………………………………………………………………………………………………………………………………………………….......... They differ according to the chemical composition of their variable side chain (the ‘R’ group) ………………………………………………………………………………………………………………………………………………….......... ………………………………………………………………………………………………………………………………………………….......... Explain, with the aid of the diagram, the levels of protein structure and indicate their significance Primary Structure: The order / sequence of amino acids within a polypeptide chain ………………………………………………………………………………………………………………………………………………….......... Formed via peptide bonds between the amine and carboxyl groups of adjacent amino acids ………………………………………………………………………………………………………………………………………………….......... Primary structure determines all subsequent levels of protein structure ………………………………………………………………………………………………………………………………………………….......... ………………………………………………………………………………………………………………………………………………….......... Secondary Structure: The folding of a polypeptide chain into repeating arrangements (alpha helices or beta-pleated sheets) ………………………………………………………………………………………………………………………………………………….......... Formed via hydrogen bonds between the amine and carboxyl groups of non-adjacent amino acids ………………………………………………………………………………………………………………………………………………….......... ………………………………………………………………………………………………………………………………………………….......... Tertiary Structure: The overall three dimensional shape of the polypeptide chain ………………………………………………………………………………………………………………………………………………….......... Formed via a variety of bonds / interactions between the variable side chains (R groups) ………………………………………………………………………………………………………………………………………………….......... These interactions may include hydrogen bonds, ionic bonds, disulphide bridges or hydrophobic interactions ………………………………………………………………………………………………………………………………………………….......... ………………………………………………………………………………………………………………………………………………….......... Quaternary Structure: The presence of multiple polypeptides or prosthetic groups to form a biologically active protein ………………………………………………………………………………………………………………………………………………….......... Not all proteins will have a quaternary structure ………………………………………………………………………………………………………………………………………………….......... ………………………………………………………………………………………………………………………………………………….......... Protein Function List seven functions of protein, providing an example for each Structure (e.g. spider silk, collagen) S ……………………………………………………………………………………………… Hormones (e.g. insulin, glucagon) H ……………………………………………………………………………………………… Immunity (e.g. antibodies) I ……………………………………………………………………………………………… Transport (e.g. haemoglobin) T ……………………………………………………………………………………………… Sensitivity (e.g. rhodopsin) S ……………………………………………………………………………………………… Movement (e.g. actin, myosin) M ……………………………………………………………………………………………… Enzymes (e.g. catalase, Rubisco) E ……………………………………………………………………………………………… Define denaturation A loss of protein structure resulting in a loss of biological activity ………………………………………………………………………………………………………………………………………………….......... ………………………………………………………………………………………………………………………………………………….......... Identify two factors that can cause protein denaturation and explain how this occurs Temperature (Heat) 1. …………………………………………………………………………………………………………………………………………………... Thermal energy breaks hydrogen bonds responsible for tertiary structure …………………………………………………………………………………………………………………………………………………... A loss of tertiary structure results in a loss of function …………………………………………………………………………………………………………………………………………………... pH 2. …………………………………………………………………………………………………………………………………………………... Amino acids are zwitterions – possessing both positive and negative regions (amine and carboxyl groups) …………………………………………………………………………………………………………………………………………………... Altering the pH will change the charge and solubility of the protein (changing the structure) …………………………………………………………………………………………………………………………………………………... Outline the relationship between genes and polypeptides Genes are sequences of DNA that encode polypeptides ………………………………………………………………………………………………………………………………………………….......... Typically, one gene equals one polypeptide – however exceptions exist (e.g. tRNA genes) ………………………………………………………………………………………………………………………………………………….......... Define proteome The totality of proteins expressed within a cell, tissue or organism at a given time ………………………………………………………………………………………………………………………………………………….......... …………………………………………………………………………………………………………………………………………………..........