Tutor profile: Heide B.
Subject: Organic Chemistry
What is the most stable structure of cyclohexane, and why?
Cyclohexane is most stable in its chair conformation. This is because a flat cyclohexane has a large amount of torsional strain, so the folding of this conformation into a chair position minimizes this torsional strain.
In fasting conditions, how do the main metabolic processes change?
Under fasting conditions, blood glucose is depleted. In order to provide fuel for tissue function, therefore, the body must create this fuel rather than receiving it from the diet. Since glycolysis breaks down sugars, this pathway slows under fasting conditions, whereas glyconeogenesis quickens to create glucose. The TCA cycle slows, as it breaks down fuel rather than creating it. The reductive reactions of pentose phosphate pathway also slow down, as these reactions are used to create NADPH equivalents for fatty acid synthesis (which stores fuel rather than releases it for use). Fatty acids will be released from adipose tissue and then broken down in the liver to release ketone bodies for fuel. In addition, the backbones of amino acids will be broken down in the urea cycle to convert the carbon backbone into sugars.
What is the central dogma of biology?
The central dogma of biology describes process of translating DNA (our genetic blueprint) into proteins (the agents of many functions in a cell). It is known as the 'central' dogma because DNA, RNA, and proteins are three of the most important macromolecules across all life forms. The central dogma is that DNA->RNA->protein; in other words, DNA is transcribed into RNA, and RNA is transcribed into protein (with some additional occasions of reverse transcription).
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