Question

a. Do you think ethylene works across long or short distances? Explain why.

b. What might lead to the different physiological responses (fruit ripening, flower fading, leaf senescence) in response to ethylene?

c. Would you predict that the timing of the response to ethylene occurs on a long- or short-term basis? Explain why.

d. What is the subcellular localization of the ethylene receptor? Based on this information, what would you predict about the structural properties of ethylene (without looking it up)? e. We talked about several components of cell-surface receptor-mediated signaling: signal molecule, receptor, intracellular signaling molecules, effector protein, response. Label the applicable components on the ethylene signaling pathway.

Answer 1

ANS a) Ethylene works long distances as it's four hydrogen atoms bound to a pair of carbon atoms which are linked through a double bond. all six atoms that contain ethylene are coplanar. the h-c-h perspective is 117.4°, close to the a 120° for best sp² hybridized carbon. the molecule is likewise distinctly rigid: rotation approximately the c-c bond is a high electricity technique that calls for breaking the ?-bond.The ?-bond in the ethylene molecule is liable for its useful reactivity. the double bond is a area of high electron density, as a consequence it's miles prone to assault via electrophiles. many reactions of ethylene are catalyzed with the aid of transition metals, which bind transiently to the ethylene using each the ? and ?* orbitals.

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ANS b) The position of ethylene inside the leaf boom and improvement has been showed physiologically the use of ethylene inhibitors, and genetically using ethylene-insensitive mutants or transgenic plant life missing the key enzymes of ethylene biosynthesis it's been found that ethylene reaction factor5 (erf5) and erf6, in arabidopsis, improve leaf boom to environmental challenges ethylene-caused discounts in leaf increase were pronounced in pea plant life, around which rhizobacteria with enhanced acc deaminase interest had been introduced to soil . apparently, the decrease leaf vicinity become discovered in lettuce grown in closed environments, where ethylene made from the flora reached stressful tiers. the plants showed decrease relative leaf boom rates in comparison to the ones grown in bins from which the ethylene were scrubbed

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ANS c) Historically, lemon growers saved harvested green lemons in sheds which have been stored heat by kerosene warmers. lemons were stored until they became yellow and ripened for market. but, whilst cutting-edge heating systems had been added in sheds, the lemons never grew to become yellow on time. research determined out that the primary element that inspired ripening in kerosene warmed sheds become the small quantities of ethylene given off by way of kerosene heaters.

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ANS d) Ethylene production is induced all through positive tiers of growth inclusive of germination, ripening of culmination, abscission of leaves, and senescence of flora. ethylene production also can be prompted through a spread of outside aspects such as mechanical wounding, environmental stresses, and certain chemicals which include auxin and other regulators.The pathway for ethylene biosynthesis is called the yang cycle after the scientist shang fa yang who made key contributions to elucidating this pathway.ethylene is biosynthesized from the amino acid methionine to s-adenosyl-l-methionine (sam, additionally referred to as adomet) through the enzyme met adenosyltransferase. sam is then transformed to one-aminocyclopropane-1-carboxylic acid (acc) through the enzyme acc synthase . the hobby of acs determines the fee of ethylene production, therefore regulation of this enzyme is fundamental for the ethylene biosynthesis. the very last step requires oxygen and entails the action of the enzyme acc-oxidase (aco), formerly called the ethylene forming enzyme (efe). ethylene biosynthesis may be precipitated by using endogenous or exogenous ethylene. acc synthesis increases with excessive tiers of auxins, especially indole acetic acid (iaa) and cytokinins.

An ethylene sign transduction pathway. ethylene permeates the membrane and binds to a receptor at the endoplasmic reticulum. the receptor releases the repressed ein2. this then activates a sign transduction pathway which activates a regulatory genes that subsequently trigger an ethylene reaction. the activated dna is transcribed into mrna that's then translated right into a useful enzyme that is used for ethylene biosynthesis.