1 / 22

Biology 12

Biology 12. Proteins. Proteins. Proteins are made up of the elements C, H, O, and N (but in no set ratio) Proteins are chains of amino acids (usually 75 or more) that bond together via dehydration synthesis 40% of the average human body is made up of protein. Proteins.

kasia
Download Presentation

Biology 12

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Biology 12 Proteins

  2. Proteins • Proteins are made up of the elements C, H, O, and N (but in no set ratio) • Proteins are chains of amino acids (usually 75 or more) that bond together via dehydration synthesis • 40% of the average human body is made up of protein

  3. Proteins • The building block of Proteins are amino acids • There are three parts to an amino acid: • Amino Group (NH2 or NH3+) • Acts as a base (accepts H+) • Carboxyl Group (COOH or COO-) • Acts as an acid (donates H+) • R Group • There are 20 different possible R groups

  4. 20 Different Amino Acids

  5. Proteins • Amino acids bond together via dehydration synthesis • The amino acids bind together with a peptide bond • The peptide bond is formed between C and N and one water is lost (dehydration synthesis)

  6. Proteins • When the original two amino acids form the beginning of the chain (with one peptide bond) it is call a dipeptide

  7. Proteins • Than the chain grows to become a tripeptide

  8. Proteins • Ultimately you end up with a polypeptide (which can have anywhere between 30 and 30,000 amino acids) • Another name for a polypeptide is protein

  9. Proteins • Every protein is different because the order of amino acids is different • The chains come together differently due to the order of the different R groups and how they bond together • This structural difference also makes the polypeptides (proteins) functionally different

  10. Levels of Protein Structure Primary structure: 1° • This is the first level of how proteins are formed • It is simply the order of amino acids joined together with peptide bonds • It is the amino acid sequence that determines the nature and chemistry of the protein • If you change the order of amino acids, the protein may not be able to do its job

  11. Levels of Protein Structure Secondary Structure: 2° • This is the second step in the formation of a protein • When a peptide bond is formed, a double bonded oxygen is left over, which is partially negative (the carboxyl group: COO-) • It is attracted to the positive NH3+ amino group from other amino acids in the chain • This attraction forms a hydrogen bond • This causes the chain to twist into either a spiral called an alpha helix or a beta pleated sheet

  12. Levels of Protein Structure Tertiary Structure: 3° • The next interactions take place between the R groups • Some R groups are reactive and will interact with other reactive R groups in the chain. These are the amino acids that are either charge or that have a sulphur atom. • The interactions (+ and – attractions and S-S bridges) will fold the molecule over into a highly specific 3-dimensional shape • It is the 3-D shape that will determine the protein’s job

  13. Levels of Protein Structure Quaternary Structure: 4° • The last level in protein formation is not seen in all proteins • However, some proteins are actually 2 or more molecules joined to form a functional protein. They are held together with an ionic bond. • Two examples: • Insulin has 2 subunits • Hemoglobin has 4 subunits

  14. The Whole Process • Interactions between R Groups • Peptide Bonds • Hydrogen Bonds • Ionic Bonds

  15. Denaturation • The final shape of a protein (its tertiary or quaternary structure) is very specific and enables it to do its job/function • Any change in a protein’s shape will affect its function • Denaturation is when a protein’s tertiary structure is lost • This happens when the bonds between the R groups are broken • When a protein is denatured, the protein can’t do its job and becomes useless

  16. Denaturation Denaturation has three common causes: • Temperature • High temperatures affect the weak hydrogen bonds and can distort or break them • This changes the structural shape • A slight increase in temperature can cause a reversible change (ex. Fever) • A high temperature increase can cause an irreversible change (ex. Cooking an egg)

  17. Denaturation • Chemicals • Heavy metals such as lead and mercury are large atoms that are attached the R groups of amino acids • They bond to the R group and distort the protein’s shape • This is usually irreversible (they usually don’t want to ‘let go”)

  18. Denaturation • pH • As some of the R groups are acids and some are bases, every protein has a preferred pH • Any change in pH causes a change in the acid-base R group interactions and this will change the shape of the protein

  19. Actin & Myosin: muscle proteins Keratin: nails, hair, horns, feathers Collagen: bones, teeth, cartilage, tendon, ligament, blood vessels, skin matrix Functions of Proteins • Structural • Proteins help make up all the structures in living things

  20. Hemoglobin Functions of Proteins • Functional • Other proteins help us to keep our bodies functioning properly and to digest our food Enzymes:are proteins that are catalysts which speed up reactions and control all cell activities.

  21. Functions of Proteins • Food Source • Once we have used up all of our carbohydrates ad fats, proteins will be used for energy • Proteins are worth the least amount of energy per gram

More Related