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Question 1
Correct
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Changes in cadherin expression are associated with
Your Answer: Tumour metastatic potential
Explanation:Cadherins play a role in maintaining cell and tissue structure, and in cellular movement. The E-cadherin–catenin complex plays a key role in cellular adhesion; loss of this function has been associated with greater tumour metastasis.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 2
Correct
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Cyclic AMP activates the following enzyme
Your Answer: Protein Kinase A
Explanation:Cyclic AMP works by activating protein kinase A (PKA, or cAMP-dependent protein kinase). Protein kinase A can also phosphorylate specific proteins that bind to promoter regions of DNA, causing increases in transcription.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 3
Incorrect
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Microtubule disassembly:
Your Answer: Occurs at the positive end only
Correct Answer: Occurs at the positive and negative end
Explanation:Dynamic instability refers to the coexistence of assembly and disassembly at the ends of a microtubule. The microtubule can dynamically switch between growing and shrinking phases in this region. Although both assembly and disassembly occur at both ends they occur preferentially at the (+) end.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 4
Incorrect
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With regard to cell membrane proteins:
Your Answer: Those that act as pumps transport substances down an electrochemical gradient
Correct Answer: Carriers are involved in facilitated diffusion
Explanation:Pumps use a source of free energy such as ATP to transport ions against a gradient and is an example of active transport. Unlike channel proteins which only transport substances through membranes passively, carrier proteins can transport ions and molecules either passively through facilitated diffusion, or via secondary active transport. Channels are either in open state or closed state. When a channel is opened, it is open to both extracellular and intracellular. Pores are continuously open to both environments, because they do not undergo conformational changes. They are always open and active.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 5
Correct
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Which ion channel is a dimer?
Your Answer: Cl- channel
Explanation:A dimer is a chemical structure formed from two similar sub-units. Chloride channels or exchangers are composed of two similar subunits—a dimer—each subunit containing one pore.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 6
Incorrect
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Free radicals are best defined by which of the following statements.
Your Answer: Atoms or molecules with electrical charge
Correct Answer: Atoms or molecules with unpaired electrons
Explanation:Free radicals form when one of weak bond between electrons is broken and an uneven number of electrons remain. This means the electron is unpaired, making it chemically reactive and attempt to steal an electron from a neighbouring molecule to stabilize itself.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 7
Correct
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With regard to the cell membrane:
Your Answer: It consists of an outer hydrophilic & an inner hydrophobic layer
Explanation:The cell membrane consists primarily of a thin layer of amphipathic phospholipids that spontaneously arrange with the hydrophobic tail regions on the inside and the hydrophilic head regions outside. Membranes typically have a large content of proteins, around 50% of membrane volume.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 8
Incorrect
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Which intercellular connections are responsible for fastening the cells to one another?
Your Answer: Connexons & tight junctions
Correct Answer: Hemidesmosomes, zonula adherens & desmosomes
Explanation:There are three major types of cell junction:Adherens junctions, desmosomes and hemidesmosomes (anchoring junctions),Gap junctions (communicating junction) &Tight junctions (occluding junctions)
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 9
Incorrect
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Selectins
Your Answer: Interact with protein ligands on immunoglobulins
Correct Answer: Interact with carbohydrate ligands or mucin complexes on leucocytes and endothelial cells
Explanation:Selectins are involved in constitutive lymphocyte homing, and in chronic and acute inflammation processes, including post-ischemic inflammation. Each selectin has a carbohydrate recognition domain that mediates binding to specific glycans on apposing cells.
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This question is part of the following fields:
- Cell Biology
- Medicine
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Question 10
Incorrect
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What is the enzyme that is involved in the formation of citrulline?
Your Answer: Phosphoenolpyruvate carboxykinase
Correct Answer: Ornithine transcarbamoylase
Explanation:Carbamoyl phosphate is converted to citrulline by ornithine transcarbamoylase.
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This question is part of the following fields:
- Cell Biology
- Medicine
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