Tut 3 Membranes Protein trafficking(student)

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 MCQ 1 The structure of phospholipids includes the following: 1 glycerol linked to fatty acids 2 hydrophobic fatty acid chains 3 ester bonds 4 phosphate group attached to glycerol 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 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 1 2 3 4 5 6 7 8 9 10

St Andrew’s Junior College The Cell and Biomolecules of Life / Membranes & Protein Trafficking 2021 H1 Biology 2 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. 4 Structure C is found only on one surface of the membrane. A 1, 2 and 4 B 2, 3 and 4 C 1 and 2 D 2 and 3 4 The cell surface membranes of plants adapted to cold conditions change as the weather gets colder, allowing the plants to carry out exocytosis. Which change occurs? A a decrease in the ratio of proteins to saturated phospholipids B a decrease in the ratio of unsaturated phospholipids to saturated phospholipids C an increase in the ratio of proteins to unsaturated phospholipids D an increase in the ratio of unsaturated phospholipids to satur ated phospholipids

St Andrew’s Junior College The Cell and Biomolecules of Life / Membranes & Protein Trafficking 2021 H1 Biology 3 5 The cell membrane of an African desert rat and that of the Arctic red fox are compared to investigate their composition. Which of the following is the most probable makeup of the respective membranes? Amount of saturated fatty acids Amount of cholesterol Arctic red fox Desert rat Arctic red fox Desert rat A Low High Low High B High Low Low Low C Low High High High D High Low High Low 6 What are the features of facilitated diffusion? uses proteins in membrane uses ATP molecules move down a concentration gradient A √ √ √ B x √ √ C √ x √ D √ √ x 7 Which statements about the components of the cell surface membrane are correct? 1 Diffusion can take place through lipids and protein pores. 2 Endocytosis only involves lipids. 3 Facilitated diffusion only involves proteins. 4 Osmosis only involves proteins. A 1, 2, 3 and 4 B 1, 3 and 4 C 1 and 3 D 2 and 4

St Andrew’s Junior College The Cell and Biomolecules of Life / Membranes & Protein Trafficking 2021 H1 Biology 4 8 The diagram shows two pathways, X and Y, through which molecules can diffuse across a cell surface membrane. Which row correctly shows possible pathways for lipids, water and glucose? lipids water glucose A X only X and Y Y only B X only Y only Y only C X and Y X only X and Y D X and Y X and Y X only 9 Liposomes are spherical vesicles consisting of a phospholipid bilayer. They can be designed to carry pharmaceutical drugs into cells. The figure below shows the structure of a liposome and two potential drugs, drug 1 and drug 2, that it can carry. Which of the following statements are true? 1 Liposomes can carry both hydrophobic and hydrophilic drugs. 2 The centre of the liposome is aqueous. 3 Liposomes are able to fuse with the cell surface membrane of a cell. 4 Liposome-based membranes have a rigid structure. A 1 and 2 only B 1, 2, and 3 only C 2 and 3 only D 2, 3, and 4 only

St Andrew’s Junior College The Cell and Biomolecules of Life / Membranes & Protein Trafficking 2021 H1 Biology 5 10 Two chemicals, Brefeldin A and Monensin, are inhibitors of certain cellular processes: - Brefeldin A inhibits the transport of substances from the rough endoplasmic reticulum to the Golgi apparatus. - Monensin inhibits the formation of post-Golgi vesicles. Researchers tested several samples of cells that produce a particular protein called APRIL with the above named inhibitors. The results are shown in the table below. Sample Functional Protein formation Secretion 1 Functional Protein APRIL formed Protein APRIL not secreted from the cells 2 Functional Protein APRIL not formed Protein APRIL not secreted from the cells 3 Functional Protein APRIL formed Protein APRIL secreted from the cells From this information, which treatment was each sample subjected to? A Sample 1 was treated only with Brefeldin A. B Sample 3 was treated only with Monensin. C Sample 2 was treated with Brefeldin A and Monensin. D Sample 2 was treated only with Monensin.

St Andrew’s Junior College The Cell and Biomolecules of Life / Membranes & Protein Trafficking 2021 H1 Biology 6 STQ QUESTION 1 (a) The passage of most molecules through membranes is regulated by proteins. Fig. 1.1 is a diagram showing the four main steps in the release of insulin from beta cells, which involves three types of transmembrane proteins. Fig. 1.1 Explain why transmembrane proteins are necessary for glucose, potassium ions and calcium ions to pass through cell surface membrane. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. …………..……………………………………………………………………………………[3] Describe the properties of the phospholipid bilayer and the aquaporin channels in relation to the movement of water across the cell surface membrane. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………..[4]

St Andrew’s Junior College The Cell and Biomolecules of Life / Membranes & Protein Trafficking 2021 H1 Biology 7 Suggest why there are no channels for insulin release across the membrane. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. …………..……………………………………………………………………………………[3] Describe how transmembrane proteins are embedded in the membrane. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. .....…………………………………………………………………………………………….[2] (b) Fig. 1.2 is an electron micrograph showing release of insulin from a β (beta) cell in the pancreas. Fig. 1.2 Describe how this release across the membrane occurs. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. ………………………………………………………………………………………………….. …………..……………………………………………………………………………………[3]

St Andrew’s Junior College The Cell and Biomolecules of Life / Membranes & Protein Trafficking 2021 H1 Biology 8 QUESTION 2 (a) Milk contains lipids, carboh