biological molecules *2

• what is a covalent bond?

  A strong chemical bond where two atoms share a pair of electrons
• what is an ionic bond?

  a chemical bond formed by the attraction between two oppositely charged-ions
• What is a hydrogen bond?

  A weak chemical bond between the positive charge on a hydrogen atom and the negative charge on the atom of an adjacent molecule
• define cohesion?

  the force of attraction between water molecules which makes them stick to each other
• describe the process of adhesion in plants ?

  water molecules are attracted to the impermeable walls of xylem tissue
• what is a monomer ?

  A monomer is a molecule that can join together with other molecules to form a polymer.
• what is a polymer ?

  A polymer is a large molecule made up of repeating subunits called monomers.
• what is a condensation reaction ?

  A reaction that forms a chemical bond between two molecules and eliminates a water molecule.
• what is a hydrolysis reaction ?

  A reaction that breaks a chemical bond between two molecules and uses a water molecule.
• what is a monosaccharide ?

  a single sugar unit from which larger carbohydrates or polysaccharides are made
• what are the two structurally different forms of glucose ?

  alpha glucose and beta glucose
• name of pentose sugar found RNA ?

  Ribose
• what is a glycosidic bond ?

  a covalent bond between a carbohydrate molecule and a hydroxyl group on another molecule resulting from a condensation reaction
• what are three monosaccharides commonly found in disaccharides ?

  fructose,galactose and glucose
• what is a disaccharide?

  a molecule formed by the condensation of two monosaccharides
• how is sucrose formed ?

  Sucrose is formed through a condensation reaction between glucose and fructose.
• how is lactose formed ?

  Lactose is formed through the enzymatic reaction between glucose and galactose.
• how is maltose formed ?

  Maltose is formed through the condensation reaction of two glucose molecules.
• what is a polysaccharide ?

  a polymer molecule formed from many monosaccharides joined by glycosidic bonds
• describe the structure of starch?

  a polysaccharide made up of many alpha glucose molecules joined by glycosidic bonds
• two polysaccharide molecules known as starch?

  Amylose and amylopectin.
• describe the structure of amylose ?

  alpha glucose molecules linked by 1-4 glycosidic bonds forming a long chain twisted to form a helix
• describe the structure of amylopectin ?

  Amylopectin consists of alpha glucose molecules with long chains linked by 1,4 glycosidic bonds and branches linked by 1,6 glycosidic bonds.
• describe the structure of glycogen?

  A branched polysaccharide made up of many glucose molecules with long chains linked by 1,4 glycosidic bonds and branches formed by 1,6   glycosidic bonds.
• what is the structure of cellulose ?

  unbranched polysaccharide formed of beta glucose, linked by 1,4 glycosidic bonds
• why are starch and glycogen good storage molecules ?

  they are insoluble in water meaning they don't affect the water potential of the cell
• why does starch and glycogen being coiled make them good storage molecules ?

  it makes the molecules compact
• why does starch and glycogen being branched make them good storage molecules?

  as they have more ends for fast hydrolysis
• what chemical elements make up lipids ?

  carbon, hydrogen and oxygen
• what is the structure of a triglyceride ?

  glycerol backbone with three fatty acid chains
• what is the bond formed when a fatty acid combines with a glycerol?

  ester bond through the process of esterfication
• what is a saturated fatty acid?

  A fatty acid with no double bonds in its carbon chain.
• what is an unsaturated fatty acid?

  A fatty acid with one or more double bonds in its carbon chain.
• what is the structure of a phospholipid?

  it is a molecule with two fatty acids and a phosphate group bonded to one molecule of glycerol formed by condensation reactions
• define hydrophillic ?

  attracted to and soluble in water
• define hydrophobic ?

  repelled by and insoluble in water
• what are the five elements that make up a protein?

  carbon, hydrogen, oxygen, nitrogen and sulfur
• what is a peptide bond?

  a covalent bond between two amino acids resulting from a condensation reaction
• what is a dipeptide?

  A dipeptide is a molecule composed of two amino acids joined together by a peptide bond, by a condensation reaction
• what is a proteins primary structure?

  The sequence of amino acids in a protein.