Lecture : Bio Notes 201 - Tryptophan

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azaillia

30 Mar 2023

School

UCF

Department

Biology

Course

BSC 2010C

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Document Summary

Tryptophan is one of the 20 amino acids that make up proteins and is classified as an essential amino acid because it cannot be synthesized in the body and must be obtained from the diet. It is an aromatic amino acid, meaning that it contains a ring structure in its chemical structure. Tryptophan has a complex structure, consisting of a two-carbon chain with an indole-containing side chain. Tryptophan plays a critical role in protein synthesis, as it is incorporated into proteins during the process of translation. Tryptophan is also a precursor to several important molecules in the body, including serotonin and melatonin. Serotonin is a neurotransmitter that is involved in the regulation of mood, appetite, and sleep, while melatonin is a hormone that is involved in the regulation of the sleep-wake cycle. In addition to its role in protein synthesis and the synthesis of important molecules, tryptophan has also been studied for its potential therapeutic benefits in various conditions.

Related Questions

Bacterial cells can take up the amino acid tryptophan (Trp) from their surroundings, or if there is an insufficient external supply they can synthesize tryptophan from other small molecules. The Trp repressor is a transcription regulator that shuts off the transcription of genes that code for the enzymes required for the synthesis of tryptophan.

Question 1

What would happen to the regulation of the tryptophan operon in cells that express a mutant form of the tryptophan repressor that

(1) cannot bind to DNA,

(2) cannot bind tryptophan, or

(3) binds to DNA even in the absence of tryptophan?

Question 2

What would happen in scenarios (1), (2), and (3) if the cells, in addition, produced normal tryptophan repressor protein from a second, normal gene?

When tryptophan is present at high levels, synthesis of tryptophan in bacteria is regulated allosterically when

A. two molecules of tryptophan bind regulatory sites on the first enzyme in the pathway for tryptophan synthesis, causing a change in conformation that inhibits the enzyme activity, and thus decreases tryptophan biosynthesis

B. two molecules of tryptophan bind the Trp repressor, causing a change in conformation so that the repressor is inhibited from binding to the operator

C. two molecules of tryptophan bind the Trp repressor, causing a change in conformation so that the repressor binds the operator and blocks expression of the genes encoding the enzymes that synthesize tryptophan

D. two molecules of tryptophan bind the Trp repressor, causing a change in conformation so that the repressor binds the operator and increases the level of expression of the genes encoding the enzymes that synthesize tryptophan

E. two molecules of tryptophan bind regulatory sites on the first enzyme in the pathway for tryptophan synthesis, causing a change in conformation that activates the enzyme activity, and thus increases tryptophan biosynthesis

The presence of the amino acid tryptophan in bacterial growth medium leads to reduced production of the enzymes necessary for tryptophan synthesis. What are the two mechanisms found in E. coli that reduce the rate of enzyme production? Briefly describe how tryptophan affects these processes.

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Lecture : Bio Notes 201 - Tryptophan

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