Which of the following is not true of a codon?
a. it may code for the same amino acid as another codon.
b. it never codes for more than one amino acid.
c. it extends from one end of a trna molecule.
d. it is the basic unit of the genetic code.

It extends from one end of a tRNA molecule. (Ans. C)

Explanation:

Codon or genetic code, the sequence of nucleotides in DNA and RNA which determines the amino acid sequence of the proteins. The linear sequence of nucleotides present in DNA has the information for protein sequence, proteins are not directly synthesized from DNA, an mRNA molecule is synthesized from DNA and complete the formation of proteins.

RNA is composed of 4 nucleotides adenine, cytosine, uracil and guanine. Three nucleotides constitute a unite which is called Codon, which helping to codes the amino acids. Example AUG is a codon that specifies the amino acid methionine. It is found at the starting of every mRNA and indicates the start of a protein.

There are 64 codons, 3 of them are not coding for an amino acid but indicate the end of the protein, the remaining 61 codons specify the 20 amino acids which help in makeup the proteins.  

identify the dna change shown in the diagram and explain how that change can result in the increased genetic diversity often seen among siblings.identify the dna change shown in the diagram and explain how that change can result in the increased genetic diversity often seen among siblings.v

an organism's phenotype is the  form of a trait  that it  displays. for  flowercolor, a pea  plant  can  display  a phenotype of purple or white flowers. an organism's  genotype  is the alleles of a gene it contains. based on his data, mendel concluded that a phenotype can be  determined  by more than one  genotype.