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https//nuigalway.blackboard.com/webapps/assessment/take/launch.jsp?course assessment_id-34152 18course_j here on the bookmarks bar. Import bookmarks now .. Question Completion Status: QUESTION5 2 poi During which of the Miocene climate phases would you hypothesise that ecosystem changes might have led to a selective advantage for human ancestors able to metabolise ethanol in fermenting fruits? O Anytime in Miocene, 23-5 MYA O Stable warm period, 21-14 MYA O First sharp cooling, 14 MYA O Stable cooler period. 13-8 MYA O Second sharp cooling, 7-8 MYA QUESTION 6 2 points (Extra Credit) (bonus) Which protein sequence difference is most likely responsible for the change in ADH4 enzyme activity with ethanol? Negative marking with 0.5 marks subtracted for wrong answer.Explanation / Answer
5. The Miocene is a relatively recent epoch of the Earth's history with warmer climate than today, particularly the during the middle miocene , that is, approximately 17 to 15 million years ago . Although, according to scientists, the cause of warming was not only the high levels to CO2 but also to changes in changes in orography and configuration of ocean gateways. So, the correct answer should be the second one i.e.
Stable warm periods, 21 to 14 million years ago.
6. Alcohol dehydrogenases [ ADH] are a group of dehydrogenase enzymes that facilitate the interconversion between alcohols and aldehydes or ketones with the reduction of NAD^+ to NADH.
ADH4 has has the ability to efficiently metabolise alcohol eg. ethonol.
X-ray crystallography of the ADHs shows the following structure-- each subunit consists of a coenzyme and a catalytic domain. Enzymes are dimers with the dimer interface along the co-enzyme binding domain. There is a cleft between the domains where the substates bind.
The heteromers of subunits encoded by genes ADH1A, ADH1B and ADH1C repectively are tightly clustered in the ADH4 and its isomer, ADH1. Any variation in these genes is responsible for any change in enzyme activity of ADH4 with ethanol.
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