Question

release factors are an example of what researchers call molecular mimicry—meaning, a molecule of one type that mimics the structure and function of another type.
analyze the model of the release factor above. which statement best describes its structure?
at the top of the molecule, there is a lone amino acid attached that could be added to a growing protein chain.
the only elements of secondary structure are alpha - helices, and there is no tertiary structure.
the entire molecule is roughly trna - shaped, and has roughly a straight line of amino acids at the base that could interact with a stop codon.
how is it possible for the release factor to be a protein but still bind to the 3 ribonucleotides in a stop codon?
the release factor resembles trna so much that it can enter the a site at any time and bind to mrna regardless of whether a stop codon or other codon is present.
the release factor must contain some ribonucleotides in addition to amino acids that act as the anticodon and bind to the stop codon.
the r - groups at the base of the trna - shaped release factor form hydrogen bonds and other interactions with the ribonucleotides of the stop codon.
evaluate whether the following statement is true or false:
if the primary sequence of an mrna were a sentence, the stop codon in an mrna would be a period.
true
false

Explanation:

• First question: Release factors mimic tRNA. tRNA has a specific shape. The third option correctly describes the release factor's structure as tRNA - shaped with a part that could interact with a stop codon. The first option is wrong because release factors don't add amino acids to a growing protein chain. Proteins (release factors) have tertiary structure, so the second option is incorrect.
• Second question: The R - groups (side chains) of amino acids in the release factor (which is a protein) can form hydrogen bonds and other interactions with the ribonucleotides of the stop codon. Release factors don't have ribonucleotides (they are proteins made of amino acids), so the second option is wrong. Release factors don't bind to any codon at any time (they are specific to stop codons), so the first option is incorrect.
• Third question: Just as a period ends a sentence, a stop codon ends the translation process (protein synthesis) from an mRNA. So the statement is True.

Answer:

• First question: The entire molecule is roughly tRNA - shaped, and has roughly a straight line of amino acids at the base that could interact with a stop codon.
• Second question: The R - groups at the base of the tRNA - shaped release factor form hydrogen bonds and other interactions with the ribonucleotides of the stop codon.
• Third question: True