IKE/TICA 1520 module 3, Questions with accurate answers. 100% verified/ 2023

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IKE/TICA 1520 module 3, Questions with accurate answers. 100% verified/ 2023 Why are the structural differences among amino-acid-derivative (structurally derived from amino acids), polypeptide (s... mall proteins), and steroid hormones significant? A. Steroids are lipid soluble and readily cross plasma membranes, while polypeptide and most amino acid-derived hormones cannot. B. Amino-acid-derivative and polypeptide hormones are longer molecules and thus amplify signals more. C. Polypeptide hormones are the most structurally complex and induce more complex changes in target cells. D. Different structures allow two different hormones to have different effects on the same hormone receptor. - ✔✔A based on their different structures, some hormones are lipophilic (steroid hormones) which allows them to easily cross the plasma membrane. this means hormone receptors can be located within the cells. other hormones are hydrophilic (amino acid-derived, polypeptide) based on their structure, which means that they cannot easily cross the plasma membrane and thus their receptors must be located outside of the cell. this means the signal must be transduced from an extracellular to an intracellular signal, often via second messengers. signal amplification is due to the specific behavior of molecules inside the cell in response to the hormone, not the structure of the hormone itself. complexity of the hormone structure has nothing to do with the behavior it elicits in the cell, only on the shape of the receptor that binds it. hormone-receptor binding is based entirely on compatible structures; thus differently-shaped hormones cannot bind the same receptor. When a signalling molecule binds to a receptor at the cell membrane, it gets transduced. What is meant by the term "signal transduction"? A. The signal is inactivated, so that cell stops responding. B. Signal transduction is how the receptor binds to the signal. C. The signal is transmitted inside the cell in another form. D. The mechanisms by which the cell responds to the signal are ducible. - ✔✔C signal transduction is, by definition, changing an extracellular signal into an intracellular signal. in the context of hormone signaling, an extracellular hormone binds to a receptor which initiates an internal response that may involve other proteins or second messengers (non-protein signaling molecules). in the case of neurons, an extracellular neurotransmitter binds to a receptor which initiates a change in the membrane potential. true or false: Peptide hormones share general characteristics (that is, they are all polypeptide chains), thus in order to act as a hormone they all share a common three-dimensional shape. - ✔✔false Up regulation in a hormone signalling pathway means (select all that apply): A. the amount of hormone released increases B. the hormone itself has effects on non-target cells C. hormone receptors are located both inside and on the surface of the target cell D. the number of hormone receptors increases E. the sensitivity of each receptor to a hormone increases - ✔✔D. the number of hormone receptors increases true or false: The effect of a hormone on a target cell is directly related to its class: steroid, amino-acid derived, or polypeptide (that is, all steriod hormones have similar effects, all amino-acid derived hormones have similar effects, etc). - ✔✔false When a steroid-based signaling molecule binds to its receptor, it is likely A. that no response will result B. the target cell will be inhibited C. the target cell will be stimulated D. the receptor for the hormone is within the target cell E. the receptor for the hormone is on the surface of the target cell - ✔✔D. the receptor for the hormone is within the target cell Signaling moecules based on amino-acid derivatives cause similar cell responses as polypeptides as these two classes of moecules are chemically related (polypeptides are short chains of amino acids), and their receptors are thus also similar. A. True B. False C. Amino acids cannot act as signaling molecules D. Polypeptides (proteins) cannot act as signaling moelcules - ✔✔B. false How is the signal from a steroid hormone amplified? A. Multiple steroid hormones can enter the nucleus B. The steroid hormones have to form dimers to be functional C. The steroid hormone activates repeated transcription of target genes D. Each mRNA copy of a steroid-hormone target gene can be translated into protein multiple times - ✔✔C and D signal amplification is anything that causes greater numbers of signaling molecules or greater numbers of response regulators/greater degree of response. the typical response to steroid hormones is changes in gene expression, as the hormone+receptor complex activates or represses transcription of specific genes. as long as the hormone+receptor complex is bound to a specific gene, RNA polymerase will keep transcribing it, generating many thousands of copies of the mRNA. once the mRNA exists the nucleus, it can serve as a template for translation hundreds to thousands of times, generating a new copy of the protein each time. this results in huge numbers of proteins generated in response to only a small number of hormone molecules. A drug that that disrupts (prevents) bacterial quorum sensing (select all that apply): A. Would result in unregulated bacterial population growth B. Would arrest the bacterial cell cycle (stop them from dividing) C. Would be useful as an antibiotic D. Would prevent biofilm formation E. Would prevent bacterial virulence F. Would not effectively prevent infections because bacteria would not be killed - ✔✔C. Would be useful as an antibiotic and D. Would prevent biofilm formation Plants bend towards light in a process called phototropism. Which of the following is true of this process? A. Plants use phototropins to receive a blue-light signal B. Red and far-red light trigger bending in different directions C. Auxin is produced in cells in response to light and causes bending D. Asymmetric auxin distribution causes differential cell elongation that causes bending - ✔✔A and D phototropins are proteins that detect blue light, the signal which causes phototropism. the response (bending) is due to the asymmetric distribution of auxin in response to the angle of the blue light. auxin is produced constantly at the apical meristems, but its distribution is affected by the angle of blue light. the auxin redistributes toward the shaded side of the plant, causing differential cell expansion and thus causing bending toward the light. red and far-red light are involved in regulating germination, not phototropism. If a plant failed to grow taller, which of the following hormones might you artificially add to stimulate growth? A. auxins B. gibberellins C. abscisic acid D. ethylene E. cytokinins F. blue light - ✔✔A, B, and E auxins are produced in apical meristems and are master regulators of plant growth. gibberellins promote plant growth, but only in the presence of auxin. cytokinines promote cell division (which leads to growth), but only in the presence of auxin. abscisic acid regulates dormancy, both in the seed (prevents germination) and in the photosynthetic tissue (closes gaurd cells of stomata in response to drought) ethylene promotes senescence (aging), both in fruit (ripening) and in leaf abscission (falling off of dead leaves in fall/winter) blue light dues stimulate plant growth, but it is an external stimulus, not a hormone Which of the following signals indicates shade to a plant? A. light quantity B. far-red light C. blue light D. red light - ✔✔B far-red light is the some of the only light that passes through leaves. thus if a plant is receiving primarily far-red light and not other wavelengths, this indicates that the plant is growing under other plants. Which step must occur first in a plant's defense against a pathogen? A. Deployment of MeSA [Show More]

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