Practise food tests, carbohydrate and lipid chemistry, protein structure and water properties while linking monomers, bonds and molecular shape to biological roles.
Smooth muscle is a tissue composed of smooth muscle cells. The cells contain cytoplasm packed with proteins that are involved in contraction and relaxation.
Caldesmon is a large protein with a number of binding sites to attach to other proteins.
Caldesmon exists in two different forms, H-caldesmon and L-caldesmon.
H-caldesmon helps to regulate contraction and relaxation in smooth muscle cells.
L -caldesmon is found in some non-muscle cells, where it also acts as a regulatory protein.
- Caldesmon is coded for by a gene known as CALD1.
- CALD1 has 17 exons.
- The primary structure of H-caldesmon has a repeating sequence in the middle of the amino acid chain that is not present in L-caldesmon.
Suggest how the two different forms of caldesmon can still have similar functions, even though they have a different primary structure.
What is a feature of triglyceride molecules?
They are hydrophobic molecules.
They are molecules with a single ester bond.
They are polar molecules.
They are water-soluble molecules.
Fig. 1.1 is a diagram representing part of the phospholipid bilayer of a cell surface membrane.
Fig. 1.1
Identify the part of a phospholipid molecule, labelled A in Fig. 1.1, that forms bonds with the phosphate heads and with the fatty acid tails.