Protein Synthesis The making of Proteins Proteins: a combination of Amino acids DNA determines what the protein will look like RNA puts the protein together RNA takes DNA instructions to the Ribosomes RNA reads DNA’s message & puts the protein together
Step #1: Transcription DNA makes the RNA strand (mRNA) that will leave the nucleus and go to the ribosomes Transcription = DNA → mRNA
Transcription Steps: 1. DNA unzips & RNA in the cytoplasm bonds to make mRNA 2. mRNA leaves nucleus & goes to ribosomes Transcription
DNA to mRNA
Codon Each combination of 3 bases (AUG, ACA) code for a specific amino acid.
Amino Acids 20 Different Amino Acids Chemical building blocks of Proteins 20 Different Amino Acids More than one codon for each amino acid. (see chart) Stop Codon: stops the production of the protein
Translation / Protein Synthesis The original code for the protein from DNA is translated into a protein.
Process: 2. mRNA codons are pointed out to tRNA 1. mRNA is on ribosomes 2. mRNA codons are pointed out to tRNA 3. tRNA picks up and brings in amino acids to mRNA for protein assembly. 4. Process continues until stop codon is reached! translation
Translation:
A permanent change in the DNA sequence of a gene. Mutations A permanent change in the DNA sequence of a gene. Mutations in a gene's DNA sequence can alter the amino acid sequence of the protein, thereby changing the protein produced.
A mistake in a letter of the DNA which changes the codon Example: DNA: GCA TGC TGC GAA ACT TTG mRNA: CGU ACG ACG CUU UGA AAG Mutation: DNA: GCA TAC TGC GAT ACT TTG
Importance of Mutations: Many don’t matter (base is wrong, but same amino acid is made) Some cause drastic changes in the protein & disrupt normal functions (diseases & cancer) Some result in good variations