Question 1

What appears to be the original form of most cellular mRNAs?

Accepted Answer

The answer of What appears to be the original form...

Question 2

A space probe brings back a new life form.It is carbon-based and its genetic material is similar to Earth DNA except that it uses 6 different nucleotide bases instead of 4.Its proteins are also similar to those on Earth,but there are 28 amino acids instead of 20.You hypothesize about the genetic code for this organism.How many "letters" would you propose in each codon of the genetic code for this organism? The code should be unambiguous and may be degenerate.

Accepted Answer

The answer of A space probe brings back a new...

Question 3

Cells from a tremendously weakened embryo are examined and found to have seriously depleted levels of a number of tRNAs.If the defect resides in an RNA polymerase,which polymerase is most likely to be affected?

Accepted Answer

The answer of Cells from a tremendously weakened embryo are...

Question 4

In an experiment,you purify a cysteine-charged tRNA and chemically alter the amino acid attached to it converting it to alanine.You place this charged tRNA in a cell-free protein-synthesizing system with all of the other charged tRNAs,mRNA and other substances needed for the synthesis of proteins.What,if anything,will be different from the normal protein coded for by the mRNA in the mixture?

Accepted Answer

The answer of In an experiment,you purify a cysteine-charged tRNA...

Question 5

What amino acid is converted to selenocysteine after its attachment to its tRNA?

Accepted Answer

Serine is the amino acid that is initially attached to the tRNA and then converted to selenocysteine through a series of enzymatic reactions.

Question 6

Two-thirds of the human genome is normally transcribed to RNA,but only 10% is believed to encode for proteins.How can this discrepancy be explained?

Accepted Answer

The answer of Two-thirds of the human genome is normally...

Question 7

The process of RNA synthesis and splicing can occasionally give rise to mutations that introduce a termination codon in the middle of a coding sequence.How do cells detect and deal with these mutations?

Accepted Answer

The answer of The process of RNA synthesis and splicing...

Question 8

You are studying a particular tRNA.When charged with its amino acid,it is able to participate in protein synthesis.When interacting with the ribosome,it always enters the ribosome and associates with the P site.What amino acid is attached to the tRNA?

Accepted Answer

The answer of You are studying a particular tRNA.When charged...

Question 9

You have set up a cell-free transcription system in a test tube.By mixing DNA,RNA polymerase,sigma factors,ribonucleotides and other essential substances,you are able to make mRNAs identical to those made under a variety of conditions in the cells from which these components were isolated.What would happen if you were able to remove the sigma factor first added to the tube and replace it with another sigma factor?

Accepted Answer

The answer of You have set up a cell-free transcription...

Quiz 11: Gene Expression: From Transcription to Translation