Cells conserve energy and resources by making active proteins only when they are needed. If a protein is not needed, which of the following methods of control would be the most energy-efficient?

Question

A.  block transcription
B.  degrade the mRNA after it is made
C.  prevent translation of the mRNA
D.  degrade the protein after it is made

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?
· What key words does the question contain and what do they mean?

Gather Content
· What do you already know about transcription and translation?

Consider Possibilities
 · What other information is related to the question?
· What other information is related to the question? Which information is most useful?
· Consider the different answer options. Which can you rule out?


Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?

Answer 1

A.  block transcription

Clarify Question
· What is the key concept addressed by the question?
        o This question addresses transcription and translation.
· What type of thinking is required?
        o This question is asking you to analyze the information given, using logic, to dissect the problem and determine the answer.
· What key words does the question contain and what do they mean?
        o Energy in a cell refers to chemical energy, stored in molecules like ATP.
        o Proteins are the final output from the transcription and translation of DNA; they are made of amino acids.
        o Energy-efficient means energy-saving.

Gather Content
· What do you already know about transcription and translation?
        o Transcription is the process of turning the stored information from a DNA sequence and turning it into a temporary mRNA copy.
        o Translation takes the information from mRNA and turns it into a protein, or polypeptide – a string of amino acids.
        o What is meant by “energy-efficient”? How would making an unnecessary protein waste energy? Because both transcription and translation require energy in the form of ATP to drive the enzymes to carry out the work.
        o They also use up ribonucleotides and amino acids, which were produced using more energy from ATP.

Consider Possibilities
 · What other information is related to the question?
        o We have learned that cells are very efficient machines, and attempt to maximize their functions by using as little energy as possible. The processes of gene expression use ATP energy, thus the question tells you that to maximize function and conserve energy, the cell would want to stop making proteins when they are no longer needed.  In other words, if the process of gene expression is like an assembly line in a factory, think about where/when it would make the most sense to stop making the product (the protein).
· What other information is related to the question? Which information is most useful?
        o We have learned that MOREDESCRIPTION.
· Consider the different answer options. Which can you rule out?
        o For each answer option, consider what energy-consuming process(es) would still take place.
        o If the protein is degraded after it is made, transcription and translation both took place, using up ATP, ribonucleotides, and amino acids.
        o If the mRNA is not translated, or is degraded, then transcription still took place, using up ATP and ribonucleotides.


Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o Only by blocking transcription can the cell save all that energy. If the gene is never transcribed, then ATP, ribonucleotides, and amino acids are all saved.

Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
        o This question asked which method of control would be most energy-efficient for the cell?
        o The question required you to analyze the information given, using logic, to dissect the problem and determine the answer.
        o Did you recognize that blocking transcription would save the most energy?
        o Despite this, cells do often regulate at the level of translation as well. Why do you think this might benefit a cell despite the wasted energy?