Lab 12 REVAMP

Understand transcription and translation (importance, steps, location).

Transcription: DNA → mRNA in the nucleus. RNA polymerase copies DNA into mRNA so the instructions can leave the nucleus.

Translation: mRNA → protein at the ribosome (cytoplasm). The ribosome reads codons while tRNA brings amino acids to build a protein.

How do you transcribe DNA into mRNA?

Use complementary base pairing:

• A → U

• T → A

• C → G

• G → C

Example:
DNA: TAC GGA TTT
mRNA: AUG CCU AAA

What are codons and why are they important?

A codon is a sequence of 3 mRNA bases that codes for one amino acid or a stop signal. The order of codons determines the amino acid sequence of the protein.

What are the start and stop codons?

• Start: AUG (Methionine)

• Stop: UAA, UAG, UGA

Contrast mRNA and tRNA.

mRNA (Messenger RNA):

• Carries genetic instructions from DNA to the ribosome.

• Contains codons.

tRNA (Transfer RNA):

• Carries amino acids to the ribosome.

• Contains anticodons that match mRNA codons.

In what direction does protein synthesis occur?

The ribosome reads mRNA from 5' → 3'.

How does the anticodon relate to the codon?

The anticodon on tRNA is complementary to the codon on mRNA, allowing the correct amino acid to be added.

Example:
Codon: AUG
Anticodon: UAC

How do you use a codon table?

Read the mRNA sequence 5' → 3', separate it into codons (groups of 3), and match each codon to its amino acid. Stop at a stop codon.

. What reaction joins two amino acids? What is released?

Dehydration synthesis (condensation reaction) joins amino acids together and releases water (H₂O).

What bond links amino acids? Are electrons donated or shared?

A peptide bond links amino acids. It is a covalent bond, so the electrons are shared, not donated.