1 Biological molecules Flashcards
1.1 Monomers and Polymers
What is a monomer?
(a monomer is a smaller / repeating) unit / molecule from which larger
molecules / polymers are made
1.1 Monomers and Polymers
Explain one way in which starch molecules are adapted for their function in plant
cells. (2 marks)
- Insoluble;
- Don’t affect water potential;
OR - Helical;
Accept form spirals - Compact;
OR - Large molecule;
- Cannot leave cell.
(2 points required for full marks)
1.1 Monomers and Polymers
Describe the structure of proteins (5 Marks)
- Polymer of amino acids;
- Joined by peptide bonds;
- Formed by condensation;
- Primary structure is order of amino acids;
- Secondary structure is folding of polypeptide chain due to hydrogen
bonding;
Accept alpha helix / pleated sheet - Tertiary structure is 3-D folding due to hydrogen bonding and ionic /
disulfide bonds; - Quaternary structure is two or more polypeptide chains.
You need atleast 5 points to get full marks.
1.2 Carbohydrates
Glycogen and cellulose are both carbohydrates.
Describe two differences between the structure of a cellulose molecule
and a glycogen molecule (2 marks)
- Cellulose is made up of β-glucose (monomers) and glycogen is
made up of α-glucose (monomers); - Cellulose molecule has straight chain and glycogen is
branched; - Cellulose molecule has straight chain and glycogen is coiled;
- glycogen has 1,4- and 1,6- glycosidic bonds and cellulose has
only 1,4- glycosidic bonds
1.2 Carbohydrates
Describe the structure of glycogen (2 marks)
- Polysaccharide of α-glucose;
OR
polymer of α-glucose; - (Joined by) glycosidic bonds
OR
Branched structure
minimum 2 points to get full marks
1.2 Carbohydrates
Explain how cellulose molecules are adapted for their function in plant
cells (2 marks)
- Long and straight chains;
- Become linked together by many hydrogen bonds to form
fibrils; - Provide strength (to cell wall
minimum of 2 points to get full marks
