Genetic Mutations and Protein Synthesis Vocabulary

Definitions of Key Genetic Terms

• Deletion: A mutation where a base pair is removed from a gene.

• Exon: The sequence present in protein-coding mRNA after pre-mRNA splicing is complete.

• Frameshift Mutation: Occurs when a mutation shifts the reading frame of mRNA due to insertions or deletions.

• Insertion: A type of mutation where a new nucleotide is added into the gene.

• Intron: Non-protein-coding sequences that are removed from mRNA during processing in eukaryotes.

• Missense Mutation: A mutation that alters the coding for an amino acid, resulting in a different amino acid being produced.

• Nonsense Mutation: A mutation that results in a premature stop codon, terminating protein synthesis prematurely.

• Operon: A set of adjacent structural genes and regulatory elements that control the transcription of structural genes together (includes promoter and operator).

• Polyadenylation: Modification that adds a poly(A) tail to the 3' end of pre-mRNA, protecting it from degradation and assisting in mRNA export.

• Promoter: A DNA sequence located upstream of a gene, where RNA polymerase and transcription factors bind to initiate transcription.

Types of Mutations

• Silent Mutation: A mutation that does not result in a change in the amino acid sequence.

• Splicing: The process of removing introns and reconnecting exons in pre-mRNA to produce mature mRNA.

• TATA Box: A conserved sequence in both eukaryotic and prokaryotic promoters that is essential for the formation of the transcription initiation complex.

Delivery Methods for DNA

• Transduction: A method for viral gene delivery.

• Transfection: A method for introducing DNA into cells without using a virus.

Post-Translational Modifications of Proteins

• Chemical Group Addition: eg. Acetylation

• Complex Molecule Addition: eg. Glycosylation and lipidation

• Biopolymer Addition: eg. Ubiquitin or sumoylation

• Amino Acid Modification: eg. Phosphorylation

• Cleavage of Peptide Bonds: Proteolysis is the process of breaking down proteins into smaller polypeptides or amino acids.

Ribosome Binding Sites

• E Site (Exit): Site where tRNA exits the ribosome after its amino acid has been added to the growing polypeptide chain.

• P Site (Peptidyl): Associated with the peptidyl transferase center where peptide bonds are formed.

• A Site (Aminoacyl-tRNA): Site where tRNA brings in new amino acids; contains the decoding center.

mRNA and tRNA Sequence Matching

• Template Strand: The bottom strand of DNA which serves as the template for RNA synthesis.

  • Template DNA: 3’ TAC TTA CCT TCG TGG GCG 5’

  • mRNA: 5’ AUG AAU GGA AGC ACC CGC 3’

• Anticodon of tRNA (for second amino acid): 5’ GGU 3’

Protein Structure Levels

1. Primary Structure: The linear sequence of amino acids in a polypeptide chain.

2. Secondary Structure: Includes hydrogen bonding, forming structures like alpha helices or beta sheets.

3. Tertiary Structure: The overall 3D shape of a protein, stabilized by various types of bonds (e.g., van der Waals forces, hydrophobic interactions, disulfide bridges).

4. Quaternary Structure: Formed when multiple polypeptide chains assemble into a larger functional complex.

Gene Amplification Using Primers

• 4-Forward Primer: Sequence located at the 5’ end of the target region.

• 3-Reverse Primer: Positioned at the end of the target sequence, allowing amplification of the desired DNA.

Plasmid Structure and Function

• ORI (Origin of Replication): Necessary for the plasmid to replicate within host cells.

• lac Promoter: Used for transcription initiation of the gene of interest.

• lacZ’: Indicator of successful insertion of the target gene into the plasmid.

• ampR: Confers resistance to ampicillin, used to select for cells that have successfully taken up the plasmid.

• Polylinker: A region containing multiple restriction enzyme sites for gene insertion.

Identifying Successful Gene Transfer

• To identify successful gene transfer, add: Nutrient Broth, Ampicillin, and IPTG to the culture medium.

Comparison of Blotting Techniques

Genetic Code Table Summary

• The table provides codons for amino acids, indicating 1-letter and 3-letter abbreviations for each, along with stop codons and the start codon (AUG).