Presentation Transcript
12-3: RNA and Protein Synthesis :12-3: RNA and Protein Synthesis In order for a gene to work, the genetic instructions in the DNA molecule must be decoded
The first step is to copy the DNA sequence into the RNA
RNA makes it possible for a single gene in a DNA molecule to make hundreds of copies
Decoding DNA :Decoding DNA
RNA has a structure like DNA, except for three differences: :RNA has a structure like DNA, except for three differences: The sugar in RNA is ribose instead of deoxyribose
RNA is single-stranded
RNA has Uracil in place of thymine
Replacing Thymine :Replacing Thymine
Three kinds of RNA molecules work together to make proteins :Three kinds of RNA molecules work together to make proteins First kind: Messenger RNA
has the instructions to put together amino acids to make a protein
Proteins are put together on ribosomes
Three kinds of RNA (continued) :Three kinds of RNA (continued) The Second kind: Ribosomal RNA (made up of proteins)
The third kind: Transfer RNA carries each amino acid to the ribosome according to the coded message in messenger RNA
RNA is copied from DNA in a process called transcription :RNA is copied from DNA in a process called transcription The enzyme RNA polymerase binds to DNA and separates the two strands
Then, RNA polymerase builds a strand of RNA using one strand of DNA that signals the template.
The sequence of DNA that signals RNA polymerase where to bind and start making RNA is called the promoter
Transcription :Transcription
The instructions for making proteins are found in the order of the four nitrogenous bases :The instructions for making proteins are found in the order of the four nitrogenous bases This code is read three letters, or nucleotides, at a time
Each codon (group of three), specifies a certain amino acid that makes up a protein. In the genetic code, some amino acids are specified by more than one codon
Instructions (continued) :Instructions (continued) One codon is a start signal for translation.
Three codons signal the end of translation
Compare/contrast DNA codons vs. RNA codons :Compare/contrast DNA codons vs. RNA codons DNA uses Thymine
RNA uses Uracil as the “anti-codon”
DNA codon chart :DNA codon chart
RNA codons :RNA codons
RNA and Protein Synthesis (Extras) :RNA and Protein Synthesis (Extras) RNA to Protein Synthesis demo
DNA to RNA and Protein Synthesis
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