(4) Genes and proteins in health and disease (A) Structure and functions of proteins (B) Gene and Chromosome Mutations

Genes and proteins in health and disease (a) State how polypeptide chains are formed State the result of folding a polypeptide chain State how proteins are held in a 3D shape State why there is a variety of protein structures and shapes Give examples of different protein functions

Protein Structure Proteins are large _____ molecules, containing _____, _____, _____ and _____. They sometimes contain _____ too. Proteins are made up of _____ _____which are linked together into long chains by _____ bonds. During _____, the amino acids are built into a specific sequence. The _____ of this amino acid chain and the _____ produced during the folding process determine the protein’s 3D structure and _____ . Shape / amino acid / function / nitrogen / oxygen / translation / transcription / hydrogen / peptide / carbon dioxide / sulphur / protein / organic / inorganic / nucleotides / carbon / bonds / folding

Protein Structure Proteins are large organic molecules, containing CARBON, NITROGEN, HYDROGEN and OXYGEN. They sometimes contain sulphur too. Proteins are made up of amino acids which are linked together into long chains by peptide bonds. During translation, the amino acids are built into a specific sequence. The folding of this amino acid chain and the bonds produced during the folding process, determines the protein’s 3D structure and shape.

Protein Structure 4 levels of protein structure: Primary Structure Secondary Structure Tertiary Structure Quaternary Structure

Protein Structure Level of structure Main function Brief description Primary Arrangement of amino acids Secondary Tertiary Quaternary

Primary structure (the arrangement of amino acids) single chain of specific amino acids linked by peptide bonds to form polypeptides.

Secondary structure (the coiling of the amino acid chain) Folding of the primary chain into coils or pleats caused by hydrogen bonds. Coil Pleat Hydrogen bonds

Tertiary structure (the coiling of the coils) The secondary chain bends and folds further due to the interactions between individual amino acids: H-bonds Strong di-sulphide bridges (S-S)

Quaternary Structure (folding of many polypeptide chains) Two or more polypeptide chains may fold and link together to form a protein with a 3D shape. Different polypeptide chains

Fibrous Proteins Fibrous proteins are built up from long parallel polypeptide chains insoluble involved in structural roles within the cell examples: keratin in hair, collagen in bone actin and myosin in muscle

Globular Proteins Two or more polypeptide chains linked to form a roughly spherical shape. Often soluble Usually involved in cell activities: - Enzymes - Hormones - Antibodies Structural role … protein channels in membrane

Conjugated Proteins A globular protein associated with a non- protein chemical. Examples : - mucus (protein and carbohydrate) - haemoglobin (protein and iron) Haem (iron) When proteins and carbohydrates combine – they form GLYCO-PROTEINS

Protein function Function Example Transport Haemoglobin Storage Proteins have a wide variety of structures and shapes resulting in a wide range of functions. Function Example Transport Haemoglobin Storage Albumin (egg white) Enzymes Cellular reactions - catalase Regulatory Hormones - insulin Movement Muscles - actin Structural Membranes, keratin Defence Antibodies

TASK: use page 46 to label your diagram

Structure of Proteins Summary https://www.youtube.com/watch?v=qBRFIMcxZNM

Genes and proteins in health and disease (a) State how polypeptide chains are formed State the result of folding a polypeptide chain State how proteins are held in a 3D shape State why there is a variety of protein structures and shapes Give examples of different protein functions