Question

gene expression—translation
how do cells synthesize polypeptides and convert them to functional proteins?
why?
the message in your dna of who you are and how your body works is carried out by cells through gene expression. in most cases this means synthesizing a specific protein to do a specific job. first, mrna is transcribed from the dna code. then, the mrna sequence is translated into a polypeptide sequence.
model 1 - codons

1. model 1 defines the code scientists have discovered that relates the nucleotide sequence of mrna to the amino acid sequence of polypeptides.

a. what do the letters u, c, a, and g in model 1 represent?
b. what do the abbreviations such as phe, ile, ala, and gly in model 1 represent?
c. the language of mrna is often described as a \triplet code.\ explain the significance of this reference.

Explanation:

• a. In the context of mRNA, the letters U (uracil), C (cytosine), A (adenine), and G (guanine) are the nitrogen - containing bases that make up the mRNA molecule.
• b. The abbreviations such as Phe (phenylalanine), Ile (isoleucine), Ala (alanine), and Gly (glycine) represent the names of amino acids. Amino acids are the building blocks of polypeptides (and ultimately proteins).
• c. The term "triplet code" is significant because it indicates that three - base sequences (codons) in mRNA are responsible for specifying a particular amino acid. For example, the codon UUU codes for the amino acid Phe. Each codon is a group of three adjacent nucleotides in mRNA, and this triplet arrangement is the key to translating the genetic information in mRNA into the correct sequence of amino acids during protein synthesis.

Answer:

a. Nitrogen - containing bases in mRNA.
b. Amino acids.
c. Three - base sequences (codons) in mRNA specify amino acids.