In 1979, a group at Cambridge discovered that in human mitochondria, UGA is not a stop codon but instead during translation results in the delivery of the amino acid tryptophan
It was extremely unexpected to discover that one organism could have two different genetic codes, and that the genetic code was not universal—it is mostly or nearly universal. The evolutionary history of the genetic code is an area of robust debate. Which of the following statements about the evolution of the genetic code is most likely true?
A. There is no chemical correspondence between codons and amino acids—the code is arbitrary in its origin.
B. The presence of genetic code alternatives directly challengesthe concept of a common ancestor for humansand E.coli.
C. Life arose twice as independent events.
D. The genetic code has a small number of alternative states but these differences cannot be used like nucleotide differences in the genome to infer phylogenies (relationships).
A
You might also like to view...
When ATP levels are high, which enzyme's activity will be directly decreased by feedback inhibition?
a. aconitase b. malate dehydrogenase c. citrate synthase d. isocitrate dehyrogenase e. fumerase
How many genes does the human genome
contain?
a. about 5,000 genes b. about 10,000 genes c. about 20,000 genes d. about 30,000 genes e. about 7,000 genes
In the ovary, an egg (oocyte) and its surrounding cells form a ______.
A. follicle B. corpus luteum C. oviduct D. endometrium
Which of the following structures allows a bacterium to propel itself through its environment?
a. microfilaments
b. intermediate filaments
c. microvillus
d. flagellum
e. microtubule