Unit 7: Molecular Genetics 7.6 Proteins

Structural Proteins Fibrous proteins that create provide structure of the body. Keratin: protein for hair and nails Actin and myosin: proteins of muscle tissue Collagens: protein for ligaments, tendons and skin

Functional Proteins Functional proteins perform a specific function within the body. Metabolic Processes: Proteins such as enzymes are catalysts for reactions Growth and Repair: Proteins such as antibodies help fight disease Communication: Protein hormones such as insulin communicate between cells and cell receptors help transport substances across the cell membrane

Basic Structure Basic Structure Monomer: amino acids Contains the following molecules: CHON(s) Amino Acids have common features. Amino Group Alpha Carbon Carboxylic Acid Group The “R” Group -different for each Amino Acid Polar or Non-Polar (Hydrophilic or Hydrophobic) Acidic or Basic Contains Sulfur (forms disulfide bridges) Called the “backbone”

The “R” Group Differs for Each Amino Acid Structure Amino Group     The “R” Group Differs for Each Amino Acid Carboxylic Acid Group “Alpha” Carbon R See p 34

Amino Acids: Leucine Structure Amino Group   Carboxylic Acid      Group Leucine “R”      Group

Proteins in the Body There are 20 different amino acids used the body. The body can synthesize 12 of the amino acids, but the rest must come from food.

Basic Structure Complex-polymer Proteins are made up of chains of amino acids The chain of amino acids is called a polypeptide. The bond between amino acids is called a peptide bond and is created through dehydration synthesis. Amino acids within the polypeptide interact with each other to create a well-defined 3-D structure. The correct structure is essential to the function of the protein. https://rmpbs.pbslearningmedia.org/resource/nvtor-sci-predictfold/wgbh-nova-the-origami-revolution-predicting-how-proteins-fold/#.WkVVd9-nFPZ

4 Levels of Protein Structure-Protein Folding Primary Structure Secondary Structure Order of Amino Acids in the Chain Determined by the gene on the DNA Folding along short sections of the polypeptide Caused by an interaction between the elements in the backbone of adjacent amino acids Forms an  helix or a  pleated sheet

4 Levels of Protein Structure-Protein Folding Tertiary Structure Quaternary Structure Whole Molecule Folding caused by interactions between R-groups in distant amino acids. Acids bond to bases Hydrophilic to hydrophilic Hydrophobic to hydrophobic Sulfur to Sulfur (creates disulfide bridges) Multiple polypeptide chains bonding to form a protein.

When Proteins Lose their Function Proteins can be denatured. Ex: heat causes it to lose its shape and its functionality. pH can also cause the protein to lose its shape and functionality.

Proteins in Food There are 8 essential amino acids that must be obtained from food. Animal products, such as meat, fish, eggs, and milk, generally contain all eight essential amino acids. Plant-based foods, such as grains and beans, do not and must be eaten in combination with other foods to obtain all 8 essential amino acids. Example: Rice and Beans