In some ciliate protozoa, the codons UAA and UAG encode glutamate, rather than acting as STOP codons. How does this compare to other species?

Question

A.  This is unusual – almost all species share the same “universal” genetic code.
B.  This is typical – every species has its own unique genetic code.
C.  This is not unusual – while most species have a similar genetic code, there are often variations for some of the amino acids.

Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?
 
Gather Content
· What do you already know about the genetic code?
 
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.  This is unusual – almost all species share the same “universal” genetic code.

Clarify Question
· What is the key concept addressed by the question?
        o This question addresses the genetic code.
· What type of thinking is required?
        o This question is asking you to take what you already know and apply it to this unfamiliar situation.
 
Gather Content
· What do you already know about the genetic code?
        o The universal nature of the genetic code allows transgenesis to work.
        o A human gene can be placed into a mouse genome and the cells of the mouse will express the gene. Similarly, a human gene can be placed into the genome of an E. coli bacterium and the bacteria will make the encoded protein.
        o This is because the cells of organisms of different species interpret genetic information identically.
        o The genetic code used to decipher the information in a gene is the same code used in bacteria, archaea, and eukaryotes.
        o There are minor variations to the genetic code, however. For example, the genetic code of mitochondria is slightly different from the genetic code used to interpret nuclear genes.
 
Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
        o The ciliates are unusual – the genetic code is nearly universal. That is why scientists are able to express transgenes correctly in different species.
  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 The question required you to take what you already know and apply it to this unfamiliar situation.
        o Did you recognize that the genetic code is nearly (but not quite) universal?