TRUE or FALSE For your responses please justify your answer. No justification fo
ID: 11721 • Letter: T
Question
TRUE or FALSE For your responses please justify your answer. No justification for answer will recieve "needs work" rating.
13. Antibodies are Y-shaped molecules that have two identical binding sites. Imagine that you have
obtained an antibody that is specific for the extracellular domain of a receptor tyrosine kinase. When
the antibody binds the receptor, it brings together two receptor tyrosine kinase molecules. If cells
containing the receptor tyrosine kinase were exposed to the antibody, would you expect the kinase to
be activated, inactivated, or unaffected? Explain your reasoning.
14. Consider two different cell types differing in their ability to respond to signaling molecule X.
Based on your knowledge of cell signaling pathways, suggest one possible explanation for why one
cell can respond to signaling molecule X while the other one cannot.
Explanation / Answer
13. Antibodies are Y-shaped molecules that have two identical binding sites. Imagine that you have
obtained an antibody that is specific for the extracellular domain of a receptor tyrosine kinase. When
the antibody binds the receptor, it brings together two receptor tyrosine kinase molecules. If cells
containing the receptor tyrosine kinase were exposed to the antibody, would you expect the kinase to
be activated, inactivated, or unaffected? Explain your reasoning.
ACTIVATED because the antibody brings the kinase molecules together by activating them.
Moreover: "Major changes are sometimes induced when the tyrosine kinase enzyme is affected by other factors. One of the factors is a molecule that is bound reversibly by a protein, called a ligand. A number of receptor tyrosine kinases, though certainly not all, do not perform protein-kinase activity until they are occupied, or activated, by one of these ligands" - quote from http://en.wikipedia.org/wiki/Tyrosine_kinase
14. Consider two different cell types differing in their ability to respond to signaling molecule X.
Based on your knowledge of cell signaling pathways, suggest one possible explanation for why one
cell can respond to signaling molecule X while the other one cannot. One reason that one cell can respond to a signaling molecule that another cannot is that the cell does not have the same receptors on its surface to receive the signal. In order to act on the signal, the cell must first receive it.
Quote from http://en.wikipedia.org/wiki/Signal_transduction
"With single-celled organisms, the variety of signal transduction processes influence its reaction to its environment.[citation needed] With multicellular organisms, numerous processes are required for coordinating individual cells to support the organism as a whole; the complexity of these processes tend to increase with the complexity of the organism.[citation needed]Sensing of environments at the cellular level relies on signal transduction;[citation needed] many disease processes, such as diabetes and heart disease arise from defects in these pathways, highlighting the importance of this process in biology and medicine.
Various environmental stimuli exist that initiate signal transmission processes in multicellular organisms; examples include photons hitting cells in the retina of the eye,[17] and odorants binding to odorant receptors in the nasal epithelium.[18] Certain microbial molecules, such as viral nucleotides and protein antigens, can elicit an immune system response against invading pathogens mediated by signal transduction processes. This may occur independent of signal transduction stimulation by other molecules, as is the case for the toll-like receptor. It may occur with help from stimulatory molecules located at the cell surface of other cells, as with T-cell receptor signaling. Single-celled organisms may respond to environmental stimuli through the activation of signal transduction pathways. For example, slime moldssecrete cyclic adenosine monophosphate upon starvation, stimulating individual cells in the immediate environment to aggregate,[19] and yeast cells use mating factors to determine the mating types of other cells and to participate in sexual reproduction.[20]"
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.