bio 2

• Negative feedback


  Stimulus causes a feedback cycle onto an effector that restores homeostasis and eliminates the original signal
• Macromolecule


  A molecule containing a very large number of atoms
• 4 Classes of macromolecules biologically relevant

  • Carbohydrate
  • Lipids
  • Proteins
  • Nucleic acids

  
• Why macromolecules are important

  • Source of energy
  • Building blocks to make our own biomolecules
  • Storage for future source of energy or building blocks
• Organic molecules


  Contain at least 2 carbon atoms that are attached to each other (carbon-carbon bond)
• Polymer


  Large organic polymers formed from many identical or similar subunits (molecules) called monomers
• Polymer formation


  Dehydration reaction when monomers join together
• Polymer breakdown

  Hydrolysis using a water molecule to break the polymer

  
• Carbohydrates


  Includes simple sugars & their polymers, made of carbon (C), hydrogen(H) and oxygen (O) at a ratio of roughly 1:2:1 (C:H:O), serve as fuel for cells and as a source of carbon to build other molecules in the body

  
• Monosaccharides

  Monomer (subunit of a polymer), many types that can vary in structure, glucose C6H12O6 is the most common

  
• Disaccharide formation


  Two monosaccharides joined together by a dehydration reaction

  
• Polysaccharides


  Polymers made up of many monosaccharide monomers, can contain 100 to 1000 monosaccharides, used for structural roles and energy storage

  
• Polysaccharides for energy storage

  • Plants: Starch
  • Animals: Glycogen
• Why animals use glycogen while plants use starch

  The enzymes that break these polymers down into their glucose monomers work from the ends of the polymers

  
• Lipids


  Macromolecules that are insoluble in water: hydrophobic, consist mostly of hydrogen and carbon and little oxygen
• Three biologically important lipids

  • Triglycerides (Fats)
  • Phospholipids
  • Steroids
• Triglycerides (Fats)


  Constructed from glycerol (a 3-C alcohol) and three fatty acids

  
• Functions of triglycerides (fats)

  Storage of energy, protect internal organs, prevent heat loss
• Saturated fats


  No carbon-carbon double bonds in fatty acid chains, straight chains that pack tightly, solid at room temperature, mostly animal fats
• Unsaturated fats


  Contain at least one carbon-carbon double bond in fatty acid chains, bent chains that don't pack tightly, liquid at room temperature, mostly plant and fish fats
• Phospholipids


  Form the major component of biological membranes, consist of one glycerol molecule, two fatty acid molecules, one phosphate group, and one small hydrophilic group
• Phospholipids in water


  Form aggregates called micelles with hydrophilic heads directed outward and hydrophobic tails pointing inward
• Phospholipids in cell membranes

  Form a lipid bilayer with hydrophilic heads at the outer and inner edges and hydrophobic tails forming the core
• Steroids


  Consist of 4 fused carbon rings, include cholesterol which is a component of cell membranes and a starting compound for other steroids
• Proteins


  The molecular tools of the cell, have a wide range of functions
• Amino acids


  The monomers of proteins, have a common sequence of atoms called a backbone and a variable side chain
• Polypeptide formation


  Amino acids joined by peptide bonds formed through dehydration synthesis
• Protein structure and function


  Different combinations of amino acids lead to different 3D protein structures which determine their function, changing the shape changes the function
• Protein denaturation


  Process of a protein losing its 3D structure, resulting in loss of function, can be caused by changes in temperature, pH or salinity