Proteins
- Created by: Buffya
- Created on: 25-05-13 20:54
View mindmap
- Proteins
- Amino acids
- Primary structure
- A condensation reaction forms a covalent peptide bond and water is eliminated
- A polypeptide chain is formed.
- Amino acids in a polypeptide chain are often called amino acid residues as part of the molecule is lost
- To calculate the number of different possibilities we need to times 20 for every amino acid
- A polypeptide chain is formed.
- The primary structure of the protein is given by the specific sequence of amino acids that make up the protein
- This is determined by the mRNA
- Protease enzymes catalyse the hydrolysis reactions
- Hormones have to be broken down so their effects are not permanent. The target cell usually contains an enzyme to do so.
- Older skin is less able to rebuild the protein collagen
- Secondary structure
- This refers to the coiling and pleating of parts of the polypeptide molecule
- Tertiary structure
- This refers to the overall 3D structure of the final polypeptide or protein molecule
- Globular proteins
- Roll up into a compact globe with hydrophobic R-groups on the inside and hydrophilic on the outside - water-soluble
- Have metabolic roles e.g. enzymes and antibodies
- Fibrous proteins
- Form fibres and are usually insoluble
- Have structural roles e.g. collagen and keratin
- Globular proteins
- Held in place by a number of different bonds and interactions
- Disulfide bridges happen between two CYSTEINE molecules (R group is sulfur) - only broken by reducing agents
- Ionic bonds between two oppositely charged amino acids
- Hydrogen bonds
- Hydrophobic and hydrophilic interactions
- Quaternary structure
- Haemoglobin
- Globular transport protein
- Made of four polypeptide subunts - each are held together by tertiary bonds
- Each subunit contains a prosthetic haem group which contains a Fe2+ ion which binds with the oxygen molecule
- Collagen
- Fibrous structural protein
- Made up of three polypeptide chains with hydrogen bonds in between
- The collagen molecules then form covalent bonds called cross-links with another collagen molecule. This is called a collagen fibril. Mnay fibrils = a fibre
- Functions
- In artery walls to prevent bursting at high pressure
- Tendons between muscles and bones
- Bones, cartilage and connective tissue are also made of caollagen
- Haemoglobin
- This refers to the overall 3D structure of the final polypeptide or protein molecule
- A condensation reaction forms a covalent peptide bond and water is eliminated
- Excess amino acids are toxic due to the amino group
- Primary structure
- Are structural components e.g. of muscle and bone
- Are enzymes, antibodies and many hormones
- Are membrane carriers and pores e.g. for active transport and facilitated diffusion
- Amino acids
Comments
Report
Report