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10.6-10.16 Genetic Information from DNA to RNA to Protein. 1. DNA genotype =proteins= phenotype=. The central concept in biology is: DNA determines what protein is made RNA takes instructions from DNA RNA programs the production of protein synthesis
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The central concept in biology is: • DNA determines what protein is made • RNA takes instructions from DNA • RNA programs the production of protein synthesis • Proteins determine the phenotype of the organism
Proteins are made into two main stages • Transcription- the transfer on genetic info from DNA to RNA molecule • Translation- transfer of info in the RNA into a protein
Discuss w/ Partner: • What is a protein? • What protein have you eaten today and/or yesterday? • What role do proteins play in your bodily functions?
mRNA Codon Chart 2. Genetic info written CODons
Transcription & Translation of codons • Genes are located on molecules of DNA • The language of DNA is the order (sequence) of nucleotides • Ex: AAGCTT • The order of the nucleotides determine which genes are made
The Genetic Code • DNA’s instructions are based on 3 nucleotides (triplet code) • The 3 nucleotide sequence (codon) are the genetic instructions from DNA to make amino acids; which together make polypeptide chains (proteins)
3. Transcription A close-up view of transcription
During transcription: • RNA polymerase (an enzyme)binds to DNA on the promoter region & separates the DNA strands.
Promoter- Region of DNA (a codon) that allows transcription to begin • Terminator- Region of DNA that signals the end of a gene & transcription stops.
There are 3 main types of RNA: • Messenger RNA (mRNA)– carry copies instructions from genes for putting together amino acids into proteins. Carry “messages” from DNA to the rest of the cell.
Ribosomal RNA (rRNA)- makes up a major part of the ribosome (proteins are put together here) True shape of a functioning ribosome
Transfer RNA (tRNA)- transfers each amino acid to the ribosome as it is specified by coded messages in mRNA.
When RNA molecules are formed, introns and exons are copied from DNA. • Introns- DNA sequences of nucleotides that do not code for a protein • Exons- sequences that does code for a protein • The introns are cut out of RNA molecules. • The exons are then spliced together to form mRNA.
Takes place on the ribosomes • Translation- the decoding of an mRNA message into a polypeptide chain (protein) • Translation begins when an mRNA molecule attaches to a ribosome. • As each codon of the mRNA molecule moves through the ribosome, the proper amino acid is brought into the ribosome by tRNA. • In the ribosome, the amino acid is transferred to the growing polypeptide chain.
In the process anticodons are formed • Anticodon- 3 unpaired bases of tRNA that are complementary to mRNA
Ribosomes • Are made of rRNA • Have a binding site for mRNA and three binding sites for tRNA molecules • The P site holds the tRNA carrying the growing polypeptide chain • The A site carries the tRNA with the next amino acid • tRNAs leave the ribosome at the E site
Steps of Translation • Initiation brings together mRNA, with tRNA Special initiator tRNA carries and attaches to the start codon
Elongation adds amino acids according to the mRNA codons • Peptide bond formation b/w a.a’s • During translocation, the ribosome moves the tRNA with the attached polypeptide from the A site to the P site • Elongation continues codon by codon to add amino acids until the polypeptide chain is completed
Termination occurs when one of the three stop codons reaches the A site
Mutations • Errors can occur during DNA replication, DNA repair, or DNA recombination • These can lead to base-pair substitutions , insertions , or deletions • Can lead to frame shifts, which move the reading frame over slightly and change the primary structure of the polypeptide
Mutagens • Are chemical or physical agents that interact with DNA to cause mutations • Physical agents include high-energy radiation like X-rays and ultraviolet light • Chemical agents include carcinogens cause cancer