In: Biology
Compare and contrast the following: (4 marks each, total 20 marks) Scanning electron microscope and confocal microscope Gated transport channels and carrier proteins – in membranes Tight junctions and desmosomes Substrate level phosphorylation and oxidative phosphorylation Non-cyclic and cyclic photophosphorylation Cell membranes are selective. Explain how the lipid bilayer determines permeability and selectivity of the membrane. Describe how microtubules help vesicles move. Differentiate the fate of proteins made at the rough endoplasmic reticulum compared to proteins made in the cystol. Summarize the roles of the extracellular matrix in animals and explain what components aid in those functions. Explain how signal molecules binding to a membrane receptor can elicit a cellular response. Which organelle would you expect to be most common in the cells of each of the following structures? Why? (2 marks each, 8 marks total) Liver Muscle Pancreas Testes What mechanisms allow ATP to be made on an “as needed” basis? Cyanide binds to cytochrome c oxidase in the electron transport chain and thus prevents the transport of electrons to oxygen. Explain how this would alter cellular respiration and energy production in a cell. Describe photorespiration and explain how plants overcome photorespiration. Why would plant cells resort to using cyclic photophosphorylation to supplement non-cyclic photophosphorylation? Outline the conditions that must be met for the cell cycle to proceed to completion. Discussion Canadian Issues 9.1 in Chapter 9 of your textbook covers the making of biofuels. Discuss one of the following two questions. Post your ideas to the Discussions area first, and then read and respond to other students’ postings. Do you agree with the production and use of biofuels? Why or why not? In some countries, governments are requiring that gasoline contain a certain percentage of ethanol and may also subsidize the production of ethanol for fuel. Discuss the pros and cons of these requirements and subsidies.
Please find the answers below:
1. Scanning electron microscope and confocal microscope
Scanning electron microscope provides a 3-dimensional high resolution image of the sample in their original form, without any labelling or dyeing agent. On the other hand, confocal microscope gives a high resolution 3-dimensional image of the sample with a coloring agent, mostly a fluorescent dye and provides a complete picture of the whole structure, say a cell with all its layers and internal structures.
2. Gated transport channels and carrier proteins – in membranes
Gated transport channels are those intra-membranous channels which are operated by molecular gates/regulators of component movement in and out the cells. These gated channels are mostly regulated by the trans-membranous movement of the molecules such as ions and governed by the potential difference created. For example, voltage-gated calcium channels are operated based upon the intra- and extra-cellular movement of calcium ions.
Carrier proteins are trans-membranous proteins found the plasma membrane extending across its width. These proteins take up the shape of a hollow tube and are largely composed of alpha helices. These protein help in transport of large materials across the cell.
3. Tight junctions and desmosomes
Tight junctions are inter-cellular continuous connections across which no transfer of material can take place. On the other hand, desmosomes are cellular connections made by plug-like extensions which fit into each other and join the membranes of two cells together.
4. Substrate level phosphorylation and oxidative phosphorylation
Substrate level phosphorulation refers to the phosphorylatory phase of a biochemical process when a redox couple is operating simultaneously, where a substrate is reduced while the other is oxidized simultaneously using ATP as the primary source of phosphate. No gaseous components are released in this process. On the other hand, oxidative phosphorylation refers to a coupled redox reaction in which simultaneous reduction and oxidation of a pair of substrates takes place while releasing an oxidzed molecule (water, hydrogen being oxidized with oxygen). For example, operated in electron transport chain in the mitochondria, releasing water molecules by reacting hyrogen ions and oxygen molecules.