Lab 12

Understand the two steps of protein synthesis – transcription and translation. Be able to explain

each process, its importance and the steps involved. Also, note the location of each step

Follow base-pairing rules: A→U, T→A, G→C, C→G. (RNA uses uracil instead of thymine)

Be able to transcribe a DNA sequence into mRNA, following complementary base pairing rule

These are nucleotide triplets. Each codon specifies one of the 20 amino acids or serves as a signal

Explain the significance of codons and how they related to amino acid sequenc

These are nucleotide triplets. Each codon specifies one of the 20 amino acids or serves as a signal

List the three stop codons and the one start codon.

• Start: AUG (also codes for methionine).

• Stop: UAA, UAG, UGA

Contrast mRNA vs. tRNA

• mRNA (Messenger): A long "recipe" or copy of DNA that carries instructions to the ribosome.

• tRNA (Transfer): A "gopher" molecule that retrieves amino acids and brings them to the ribosome

In what direction does protein synthesis occur

Both transcription and translation occur in the 5’ → 3’ direction

How does the anticodon of tRNA relate to the codon sequence of mRNA

The anticodon on the tRNA is complementary to the codon on the mRNA. They hydrogen-bond together to ensure the correct amino acid is added to the chain

Be able to utilize the codon table to generate an amino acid sequence from an mRNA sequen

Locate the first base (left), second base (top), and third base (right) of the mRNA triplet to find the specific amino acid

What type of reaction joins two amino acids together? What is released as a byproduc

Dehydration synthesis joins amino acids. Water is released as a byproduct

What type of bond links amino acids together? Are the electrons being donated or shared

A peptide bond, which is a type of covalent bond. In this bond, electrons are shared.