1 / 21

Membranes & Proteins

Membranes & Proteins Can lead to the formation of excess CHOLESTEROL Steroid that helps stabilize membranes of animal cells So why are saturated fats bad for me? Is there such a thing as a “good” fat? Polyunsaturated fats (>1 double bond) contain essential fatty acids (omega-3)

KeelyKia
Download Presentation

Membranes & Proteins

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. Membranes & Proteins

  2. Can lead to the formation of excess CHOLESTEROL Steroid that helps stabilize membranes of animal cells So why are saturated fats bad for me?

  3. Is there such a thing as a “good” fat? • Polyunsaturated fats (>1 double bond) contain essential fatty acids (omega-3) • First double bond located 3 carbons from the methyl end of the fatty acid (-CH3) • Methyl end = omega end • May protect against heart disease • Oily fish like salmon and tuna (not canned), flax & walnuts

  4. My Favourite Fat • Has two saturated stearic acids and one unsaturated oleic acid • Solid at room temperature but melts quickly in your fingers

  5. H O | || H – C – O – C – stearic acid O || H – C – O – C – oleic acid O || H – C – O – C – stearic acid | H Cocoa butter!!!!

  6. Membranes aren’t just made of phospholipids • Lots of protein (more than 50% of a membrane)!!

  7. Carboxyl (acid) group Amino group What is a protein? • Basic unit is the amino acid (e.g. glycine) H | H – N – C – C – OH | | || H H O • Amino acids differ by the type of side chain located on the central carbon

  8. Primary Structure • A series of amino acids linked together • Condensation synthesis removes a water molecule between each amino acid • Results in a peptide bond between the amino acids

  9. H | H – N – C – C | | || H H O H | N – C – C – OH | | || H H O H2O Peptide bond Condensation Synthesis H | H – N – C – C – OH | | || H H O H | H – N – C – C – OH | | || H H O

  10. Secondary Structure • The amino acid chain (polypeptide) folds back on itself to create 2 different structures: 1. Alpha helices (alpha helix) 2. Beta pleated sheets

  11. Tertiary Structure • More folding • Bond interactions between the amino acid side chains • A variety of bonds involved: Polar covalent bonds (hydrophilic interactions) Non-polar covalent bonds (hydrophobic interactions) Ionic bonds (ionized side chains)

  12. Atoms ionize = electron is donated from one atom to another (no sharing) Results in a full charge on the atom Strong bonds in air Weak in water (e.g. table salt) Electrons are shared Polar covalent bonds result in partial charges (unequal sharing) Nonpolar bonds result in no charge (equal sharing) Strong bonds Covalent VS. Ionic Bonds

  13. Polar Covalent Bonds • Tug-of-war but no one wins • Oxygen can’t pull the electrons completely away from hydrogen

  14. Ionic Bonds • One molecule wins the tug-of-war • Electrons are completely shifted from one atom to another

  15. Quaternary Structure • Is not exhibited by all proteins • Separate protein subunits interact via hydrogen bonds • A globular protein like hemoglobin has 4 protein subunits • A fibrous protein like collagen has 3 subunits

  16. Summary

  17. Cock-a-doodle-doooo! WHO CARES?!?

  18. WHO CARES?!? • Prion diseases (e.g. mad cow disease, Creuzfeldt-Jakob) • Spongiform encephelopathy • Prions are infectious proteins • Caused by normal proteins that are folded improperly • Still don’t know much!

More Related