Proteins: Building Blocks of Life Cycles of Life Proteins: Building Blocks of Life

What central role do proteins play in the chemistry of life? How do the nucleic acids DNA and RNA differ? What are the two common classes of RNA? What is accomplished by transcription? Outline the major events in the process of translation.

1. What central role do proteins play in the chemistry of life? Express the genetic information coded in the DNA. Proteins produced are not only structural but also those that function as enzymes, controlling all of metabolism.

2. How do the nucleic acids DNA and RNA differ? DNA, the sugar is deoxyribose RNA, the sugar is ribose RNA, Thymine is replaced Uracil (no ‘T’ base in RNA) (RNA is single stranded)

3. What are the two common classes of RNA? mRNA – carries the ‘code’ (instructions) to make the proteins tRNA - “taxis” which carry specific amino acids to ribosomes…. Also referred to as Transfer RNA. (rRNA – makes up portions of the ribosomes – the organelles which put proteins together from amino acids

4. What is accomplished by transcription? A portion of the DNA unwinds, allowing one of the strands to act as a template for the construction of an RNA strand The genetic information (instructions to make the protein) from the DNA is now encoded in the RNA

5. Outline the major events in the process of translation. mRNA attaches to a small ribosomal subunit Initiating tRNA (with amino acid) binds to the starting sequences of the mRNA Large ribosomal subunit joins to form an intact ribosome with two binding sites. The next coding sequence is recognized by the proper tRNA, carrying specific amino acid Amino acids are joined to the growing chain. Continues until a “STOP” sequence signals the end of the protein