Biological Molecules Flashcards
What are monomers?
-Small, basic molecular units that can form a polymer
What are polymers?
-Large, complex molecules composed of long chains of monomers joined together during a condensation reaction
Name three monosaccharides
-Glucose
-Fructose
-Galactose
Describe the difference between alpha glucose and beta glucose
-H and OH groups on right hand side are swapped
-Alpha glucose=H on top, OH below
-Beta glucose=H below, OH on top
What bond forms between two monosaccharides when they are joined together?
-Glycosidic bond
What two monosaccharides is sucrose made of?
-Glucose
-Fructose
What two monosaccharides is maltose made of?
-Glucose
-Glucose
What two monosaccharides is lactose made of?
-Glucose
-Galactose
How do you test for reducing sugars?
-Heat sample with Benedict’s solution
-Green/yellow/orange/red precipitate=positive
How do you test for a non-reducing sugar?
-Heat sample with Benedict’s solution
-Stays blue
-Add dilute hydrochloric acid
-Neutralise with sodium hydrogencarbonate
-Heat sample with Benedict’s solution
-Green/yellow/orange/red ppt=positive
Describe the structure of starch
-Amylose=long, unbranched, alpha-glucose, coiled, compact
-Amylopectin=long, branched, alpha-glucose, enzymes easily reach branches, glucose quickly released
-Insoluble in water
Describe the structure of glycogen
-Alpha-glucose
-Branched=stored glucose quickly released
-Compact
Describe the structure of cellulose
-Long
-Unbranched
-Beta-glucose
-Chains linked together by H bonds=form microfibrils
How do you test for starch?
-Iodine solution
-Blue-black=positive
Describe the structure of triglycerides
-Glycerol
-3 fatty acid tails=hydrophobic
What is a saturated fatty acid?
-Doesn’t have any double bonds between carbon atoms
What is an unsaturated fatty acid?
-Double bonds between carbon atoms, causes the chain to kink
What bond forms between a glycerol molecule and a fatty acid?
-Ester bond
What are the properties of a triglyceride?
-Hydrocarbon tails of fatty acids contain lots of chemical energy
-Insoluble in water, don’t affect water potential
What are the properties of a phospholipid?
-Heads are hydrophilic
-Tails are hydrophobic
-Form a bilayer
-Water-soluble substances can’t pass through
How do you test for lipids?
-Emulsion test
-Add ice cold ethanol
-Shake
-Add water
-Milky emulsion-positive
What is the structure of an amino acid?
R
|
H2N-C-COOH
|
H
What bond forms when amino acids are joined together?
-Peptide bond
Describe the primary structure of a protein
-The sequence of amino acids in a polypeptide chain
Describe the secondary structure of a protein
-H bonds form between amino acids in the chain
-Alpha helix shape or beta pleated sheet
Describe the tertiary structure of a protein
-Folded again
-Hydrogen bonds, ionic bonds and disulphide bridges form
-3D structure
Describe the quaternary structure of a protein
-Multiple polypeptide chains held together by bonds
-3D globular structure
How do you test for proteins?
-Add sodium hydroxide solution
-Add copper(II) solution
-Purple=positive
Describe the induced fit model
-Active site and substrate not entirely complementary
-Enzyme moulds around substrate to form an enzyme-substrate complex
What is a competitive inhibitor?
-Complementary to shape of active site
-Binds with enzyme before substrate can
-No enzyme-substrate complex can form
What is a non-competitive inhibitor?
-Binds to enzyme away from active site
-Changes shape of active site
-Substrate no longer complementary
-Can’t form an enzyme-substrate complex
