Biological Membrane & ECM (Part A) Lecture 2 - Cell & Tissue Biology PDF

Cell and Tissue Biology (MHT5007-B) Lecture 2 Biological Membrane & ECM (Part A) Dr. Farshid Sefat  Contents Biochemistry/Extracellular Matrix ◼ Fats (Lipids) ◼ Molecules in natural world ◼ Proteins ◼ Amino acids...

Cell and Tissue Biology (MHT5007-B) Lecture 2 Biological Membrane & ECM (Part A) Dr. Farshid Sefat  Contents Biochemistry/Extracellular Matrix ◼ Fats (Lipids) ◼ Molecules in natural world ◼ Proteins ◼ Amino acids ◼ DNA ◼ Biological Membrane ◼ Extracellular Matrix ◼ Cell Adhesion  Phospho-lipids ◼ Phospho-lipids are found on the cell membrane ◼ Fairly similar to triglycerides ◼ Form by condensation reaction ◼ Only has two fatty acid chains ◼ In place of 3rd fatty acid, they have a “head” group that contains phosphorous and Nitrogen  Phospho-lipids ◼ Polar head (hydrophilic) ◼ Non-polar tail (hydrophobic) Phospholipids  Amphipathic nature ◼ As there is a hydrophobic and hydrophilic component to the lipid molecule, it can be called amphipathic ◼ The ‘Head' is hydrophilic (attracted to water), ◼ The ‘Tail’ is hydrophobic 'tails' are repelled by water and are forced to aggregate ◼ These specific properties allow phospholipids to play an important role in biological structures  Phospholipid Bi-layer ◼ Bilayer sheet – found on cell membranes  Phospholipid structures Liposome: for Drug delivery ◼ Under some conditions, phospholipids can form micelles (single) and liposome (double) structures ◼ Liposome are often filled with drugs, or have specific peptides on surface for accurate targeting  Steroids Steroids = Large lipid molecule: composed of 4 connected rings of carbon atoms. Cholesterol = Best-known steroid - All cell membranes contain cholesterol - Some hormones are derived from cholesterol (Sex hormones testosterone and estrogen) Q. Sources of cholesterol ? - Diet: Meat, cream, egg - Liver can synthesize large amounts of cholesterol Fatty Acids  Amino Acids (AA) & Proteins (C, H, O, N) Proteins are the most abundant organic components of the human body 20% of total body weight All proteins contain: ✓ Carbon ✓ Hydrogen ✓ Oxygen ✓ Nitrogen ✓ Little Sulfur and phosphorus  Protein Function 1. Support = Proteins create a 3D structure of body. Provide support for cells, tissues, and organs. 2. Movement = Muscular contraction 3. Transport = Insoluble lipids, respiratory gases, minerals (Fe), hormones are carried in the blood attached to transport proteins. 4. Buffering = Proteins provide a buffering action = Balance pH changes 5. Metabolic regulation = Enzymes speed up chemical reactions in living cells. 6. Coordination and control = Protein hormones 7. Defense = - Proteins of the skin, hair, and nails protect body - Antibodies (proteins) protect us from disease  Protein Structure Proteins are long chains of organic molecules called Amino Acids (AA). The human body contains of 20 different AA. Each AA consists of a central carbon (C) atom bonded to: 1. H atom 2. Amino group 3. Carboxyl group (COOH) 4. R group or side chain  Protein Structure 1000 AA ❑ A typical protein contains = …………………….. may have 100,000 or more AA ❑ Largest protein complexes = …………………………………………… Peptide bond ❑ AA bind together by ………………………. ❑ If a molecule consists of two AA = Dipeptide ❑ 3 (Tripeptides) or more chains of AA = Polypeptides ❑ Polypeptides = More than 100 AA = Proteins ❑ Hemoglobin, keratin Example: ……………………………………………… Amino Acids & Peptide Bonds Protein Structure