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Protein synthesis and Mutations - Coggle Diagram
Protein synthesis and Mutations
Gene
Protein Synthesis
Transcription
Production of a mRNA using one strand of the gene as a template
Initiation
RNA polymerase binds to a sequence of DNA called the
promoter
(HL). Once bound, RNA polymerase separates the DNA strands, providing the single-stranded template needed for transcription.
Elongation
One strand of DNA, the template strand, acts as a template for RNA polymerase. As it "reads" this template one base at a time, the polymerase builds an RNA molecule out of complementary nucleotides, making a chain that grows from 5' to 3'.
Termination
Sequences called terminators signal that the RNA transcript is complete. Once they are transcribed, they cause the transcript to be released from the RNA polymerase.
HL
Post-transcriptional modification and Splicing
1 more item...
HL
Directionality of transcription and translation
Always 5' → 3'
Translation
Genetic code
In an mRNA, the instructions for building a polypeptide are RNA nucleotides (As, Us, Cs, and Gs) read in groups of three. These groups of three are called codons.
tRNA
One end of each tRNA has a sequence of three nucleotides called an anticodon, which can bind to specific mRNA codons.
Ribosomes
The ribosome provides a set of handy slots where tRNAs can find their matching codons on the mRNA template and deliver their amino acids. These slots are called the A, P, and E sites.
Steps
Initiation
In initiation, the ribosome assembles around the mRNA to be read and the first tRNA (carrying the amino acid methionine, which matches the start codon, AUG).
Elongation
In elongation, the mRNA is read one codon at a time, and the amino acid matching each codon is added to a growing protein chain.
Termination
It begins when a stop codon (UAG, UAA, or UGA) enters the ribosome, triggering a series of events that separate the chain from its tRNA and allow it to drift out of the ribosome.
Codes for a specific protein
Mutations
Any change in the DNA sequence of a cell or on the mRNA. Mutations can be harmful, beneficial, or have no effect.
HL
Gene Knockout
Gene knockout: Making a gene inoperative to study its function.
Used in model organisms (e.g., mice, bacteria).
Libraries of knockout organisms exist for research.
CRISPR–Cas9 Gene Editing
CRISPR–Cas9: Precision gene-editing tool.
Cas9 enzyme cuts DNA, allowing for modification.
Example: Used in disease research & genetic therapies.
Ethical concerns: Global regulations vary; efforts to harmonize policies.
Conserved Gene Sequences
Conserved sequences: Similar across species, indicating importance.
Highly conserved: Unchanged over long evolutionary periods.
Hypotheses for conservation
Essential function of the gene.
Slow mutation rates in critical regions.
