Life as we know it depends on the genetic code: a set of codons, each made up of three bases in a DNA sequence and corresponding
mRNA sequence, that specifies which of the 20 amino acids will be added to the protein during translation.Imagine that a prokaryote-like organism has been discovered in the polar ice on Mars. Interestingly, these Martian organisms use the same DNA → RNA → protein system as life on Earth, except that______
In the most general case of x bases and y bases per codon, the total number of possible codons is equal to xy .
In the case of the hypothetical Martian life-forms, is the minimum codon length needed to specify 17 amino acids is 5 (25 = 32), with some redundancy (meaning that more than one codon could code for the same amino acid). For life on Earth, x = 4 and y = 3; thus the number of codons is 43, or 64. Because there are only 20 amino acids, there is a lot of redundancy in the code (there are several codons for each amino acid).
The cell membrane functions as a selective barrier. We call these kind of membranes as differentially permeable or semi permeable membrane. It can decide what substances can pass in and out. Therefore it can surround the cytoplasm (which is the inside of a cell) to separate the cell's content from the surroundings.
