Tut 3_Membranes _ Protein trafficking(MS_Annotated)

St Andrew’s Junior College The Cell and Biomolecules of Life / Membranes & Protein Trafficking 2021 H1 Biology 1 Full Name: Civics group: 21S Index no.: Date: Core Idea 1: The Cell and Biomolecules of Life Membranes & Protein Trafficking Tutorial 3 (Annotated MS) MCQ ANSWERS 1 The structure of phospholipids includes the following: 1 glycerol linked to fatty acids (does not explain why phospholipid is amphipathic) 2 hydrophobic fatty acid chains (explains why phospholipids form a bilayer with hydrophobic tails facing inwards) 3 ester bonds (does not explain why phospholipid is amphipathic) 4 phosphate group attached to glycerol (explains why phospholipids form a bilayer with phosphate heads facing outwards) Which structure(s) enable formation of a lipid bilayer in cell surface membranes? A 1 and 3 B 2 and 3 C 2 and 4 D 1, 2 and 4 1 2 3 4 5 6 7 8 9 10 C D C D C C C A B C Ester bonds phosphoester bond

St Andrew’s Junior College The Cell and Biomolecules of Life / Membranes & Protein Trafficking 2021 H1 Biology 2 2 The cell surface membrane structure is described as a ‘fluid mosaic’. Which statement describes the ‘mosaic’ part of the cell surface membrane? A the different patterns that are obtained by the moving phospholipid molecules B the random distribution of cholesterol molecules within the phospholipid bilayer C the regular pattern produced by the phospholipid heads and membrane proteins D the scattering of the different proteins within the phospholipid bilayer 3 The diagram below shows a section of a cell surface membrane. Which of the following statements are correct? 1 Structure A is found only on the extracellular surface of the membrane. 2 Structure B may contain a channel that is hydrophilic to allow ions to move across the membrane. 3 Structure C allows transport of substances across the membrane only in the presence of ATP. ➔ Carrier protein should be a transmembrane protein to allow transport of substances across membrane. Even if structure C is a carrier protein, it may not be limited to active transport as the statement implied. Carrier proteins can also refer to those which are in facilitated diffusion which can occur without hydrolysis of ATP as a source of energy. 4 Structure C is found only on one surface of the membrane. ➔ integral protein can be found in either surface of the membrane –facing the cytoplasm (inside cell) or facing the external environment (outside the cell). A 1, 2 and 4 B 2, 3 and 4 C 1 and 2 D 2 and 3 ‘mosaic’ refers to the proteins embedded in a random manner ‘fluid’ refers to proteins & phospholipids being able to move within the membrane Oligosaccharide or short carbohydrate chain transmembrane proteins (also integral proteins) integral protein channel protein which is an example of integral protein Membrane components Membrane model