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RNA and Protein Synthesis Ribonucleic acid: another type of nucleic acid that works with DNA to make proteins
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mRNA From nucleus to cytoplasm DNA transcription nucleus cytoplasm translation trait protein
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DNA vs. RNA DNA deoxyribose sugar nitrogen bases G, C, A, T T : A C : G double stranded 1 type RNA ribose sugar nitrogen bases G, C, A, U U : A C : G single stranded 3 types: M, R, & T
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Transcription Making mRNA from DNA DNA strand is the template (pattern) match bases U : A G : C Enzyme RNA polymerase
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Matching bases of DNA & RNA Double stranded DNA unzips AGGGGGGTTACACTTTTTCCCCAA
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Matching bases of DNA & RNA Double stranded DNA unzips AGGGGGGTTACACTTTTTCCCCAA
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Matching bases of DNA & RNA Match RNA bases to DNA bases on one of the DNA strands U AGGGGGGTTACACTTTTTCCCCAA U U U U U G G A A ACC RNA polymerase C C C C C G G G G A A A A A
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Matching bases of DNA & RNA U instead of T is matched to A TACGCACATTTACGTACGCGG DNA AUGCGUGUAAAUGCAUGCGCC mRNA UCCCCCCAAUGUGAAAAAGGGGUU ribosome
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protein cytoplasm nucleus trait UCCCCCCAAUGUGAAAAAGGGGUU ribosome
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How does mRNA code for proteins mRNA leaves nucleus mRNA goes to ribosomes in cytoplasm Proteins built from instructions on mRNA aa How? mRNA UCCCCCCAAUGUGAAAAAGGGGUU
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How does mRNA code for proteins? TACGCACATTTACGTACGCGG DNA AUGCGUGUAAAUGCAUGCGCC mRNA Met Arg Val Asn Ala Cys Ala protein ? How can you code for 20 amino acids with only 4 DNA bases (A,U,G,C)? ribosome aa
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AUGCGUGUAAAUGCAUGCGCC mRNA mRNA codes for proteins in triplets TACGCACATTTACGTACGCGG DNA AUGCGUGUAAAUGCAUGCGCC mRNA Met Arg Val Asn Ala Cys Ala protein ? Codon = block of 3 mRNA bases codon ribosome
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For ALL life! strongest support for a common origin for all life Code has duplicates several codons for each amino acid mutation insurance! Start codon AUG methionine Stop codons UGA, UAA, UAG The mRNA code
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How are the codons matched to amino acids? TACGCACATTTACGTACGCGG DNA AUGCGUGUAAAUGCAUGCGCC mRNA anti-codon codon tRNA UAC Met GCA Arg CAU Val Anti-codon = block of 3 tRNA bases amino acid
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mRNA to protein = Translation The working instructions mRNA The reader ribosome The transporter transfer RNA (tRNA) mRNA UCCCCCCAAUGUGAAAAAGGGGUU aa tRNA GG U aa tRNA UAC aa tRNA GA C aa AGU ribosome
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aa mRNA From gene to protein DNA transcription nucleus cytoplasm protein translation trait UCCCCCCAAUGUGAAAAAGGGGUU ribosome tRNA aa
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Mutations Changes to DNA are called mutations change the DNA changes the mRNA may change protein may change trait DNA TACGCACATTTACGTACG mRNA AUGCGUGUAAAUGCAUGC aa protein trait
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Types of Mutations 1.Point mutation: change in a single base pair in DNA (substitution) THE DOG BIT THE CAT THE DOG BIT THE CAR Missense mutation = changes amino acid Nonsense mutation = change to STOP Silent mutation = no change in protein
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Types of Mutations 2. Frameshift mutation: a single base pair is added or deleted and shifts the reading of the codons THE DOG BIT THE CAT THE DOG SBI TTH ECA T
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Mutations 3. Chromosomal mutations: any change in the structure or number of chromosomes, common in plants deletion: part of a chromosome is removed insertion and translocation: part of a chromosome breaks off and attaches to another chromosome inversion: part of a chromosome breaks off and is reinserted backwards
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Examples of chromosomal mutations deletion duplication inversion translocation 12.4
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Gene Regulation Only a small percent of genes are expressed (~3%) Genes that are expressed have a proteins that control their expression “TATA box”: sequence at the beginning of a transcription site in eukaryotes
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The Operon Four regions of DNA control the production of a protein a structural gene that holds the codons for the amino acid sequence found in the enzyme. an operator region right in front of the structural gene. a promotor region where the RNA polymerase will bind to the DNA. a regulator gene which has a role in controling the transcription from the structural gene. The combined region of the operator and structural gene is called an operon.
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Animations http://highered.mcgraw- hill.com/sites/0072437316/student_view0/chapter15/animations.html# http://learn.genetics.utah.edu/units/basics/firefly/
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