Cycles of Life

1
Cycles of Life

• Proteins Building Blocks of Life

2

• 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.

3
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.

4
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)

5
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

6
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

7
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