Which polysaccharide is an important component in the structure of many animals and fungi?
A) chitin
B) cellulose
C) amylopectin
D) amylose
A
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RNA splicing joins together the coding regions of messenger RNA in their original linear order after the removal of introns
A. true B. false
What is the key concept addressed by the question?
What will be an ideal response?
Lately, many claims concerning the health benefits of green tea have appeared in the news. Suppose you read a claim that says drinking green tea causes weight loss
The information provided states that participants were weighed at the beginning of the study, were then asked to drink 2 cups of green tea every day for 6 weeks, and finally were weighed at the end of the study. Participants who drank the tea for 6 weeks seemed to have lost some weight by the end of the study, so the researchers concluded that green tea is helpful for weight loss. This study has some obvious holes in it. Explain three things that could be done to improve the design of this study. Do not assume any information other that what has been provided.
NASA has discovered an alien life-form. You are called in to help NASA scientists to deduce the genetic code for this alien
Surprisingly, this alien life-form shares many similarities with life on Earth: this alien uses DNA as its genetic material, makes RNA from DNA, and reads the information from RNA to make protein using ribosomes and tRNAs. Even more amazing, this alien uses the same 20 amino acids, like the organisms found on Earth, and also codes for each amino acid by a triplet codon. However, the scientists at NASA have found that the genetic code used by the alien life-form differs from that used by life on Earth. NASA scientists drew this conclusion after creating a cell-free protein-synthesis system from alien cells and adding an mRNA made entirely of uracil (poly U). They found that poly U directs the synthesis of a peptide containing only glycine. NASA scientists have synthesized a poly AU mRNA and observe that it codes for a polypeptide of alternating serine and proline amino acids. From these experiments, can you determine which codons code for serine and proline? Explain. Bonus question. Can you propose a mechanism for how the alien's physiology is altered so that it uses a different genetic code from life on Earth, despite all the similarities?