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How is RNA different from DNA? RNA (Ribonucleic Acid)

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Lets Review DNA What sugar does it have? Adenine pairs with ___________ Cytosine pairs with __________ Double or single stranded?

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RNA is different from DNA RNA contains the sugar RIBOSE Uracil substitute for Thymine (A pairs with U) Single stranded

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DNA TO RNA DNA=ATTGCAC RNA=UAACGUG

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RNA? Who cares? Why is RNA important? It contains the code from DNA that is needed to make proteins!

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Three types of RNA Messenger RNA (mRNA) Code from DNA takes the code from the nucleus into the cytoplasm then to the ribosome. Transfer RNA (tRNA) Transfers amino acids from the cytoplasm to the ribosomes. Ribosomal RNA (rRNA) Part of the ribosome, links up proteins

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Protein Synthesis (The making of proteins) 2 steps in Protein synthesis Transcription Translation

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Transcription mRNA copies the code from DNA, and travels through cytoplasm to ribosome where it sticks.

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Lets Do Transcription! DNA= A G C T G A mRNA= U C G A C U

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Codons Three Three nitrogen bases. Codons code for the genetic code! Each amino acid is coded for by 3 mRNA bases If you string a bunch of amino acids together, what do you get?? 1 CODON = 1 AMINO ACID = 3 NUCLEOTIDES

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Translation Translates the mRNA into amino acids. Ribosomes attach to the mRNA strand tRNA picks up amino acids in the cytoplasm and carries them to the ribosomes (where mRNA is stuck). tRNA contains the anticodon that complements the codon on the mRNA

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Translation: The Details 1. mRNA strand leaves the nucleus, enters cytoplasm, attaches to ribosome. What are codons again??

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2. tRNA molecules pick up amino acids in cytoplam and carries them to ribosomes

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3. tRNA anticodon pairs with mRNA codon, joining the two molecules

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4. Once an amino acid has joined the chain, the tRNA leaves.

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5. The process continues until a chain of amino acids is formed and stops once a stop codon on the mRNA is reached.

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Translation DNA DNA = A T G C T A mRNA = U A C G A U (Codon) tRNA = A U G C U A (Anticodon)

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TRANSCRIPTION Takes place in the nucleus translation Moves out of nucleus into the cytoplasm & attach to ribosome

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Steps to figure out the genetic code 1.Obtain a DNA Template. (a row of DNA bases) 2.Transcribe DNA into mRNA 3.Use the codons (mRNA) to translate into amino acids

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lets practice! DNATAC mRNA (Codon) tRNA Strand (anticodon) Amino Acids AUG UAC Start

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More practice needed? DNA= TAC -GAT-GCC-ATC mRNA=tRNA= Amino Acids= AUG -CUA- CGG-UAG UAC -GAU-GCC-AUC START-LEU-ARG-STOP

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MUTATIONS Change in the genetic code May occur in the genes or the chromosomes ONLY MUTATIONS IN GAMETES MAY BE PASSED TO OFFSPRING. Two types: Point Frameshift

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Point Mutations (in the genes) Only change a few nucleotides Examples: Substitution one base is changed to another Insertion a base is added to the gene Deletion a base is removed from the gene

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Frame-shift Mutations (in the genes) Change the reading frame Examples:

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Chromosomal Mutations Change the number or structure of the chromosomes Examples: Deletion losing all or part of the chromosome Duplication extra copies of parts of the chromosome Inversion reversing the order of the pieces of the chromosome Translocation pieces of chromosomes break off and stick to another chromosome

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Significance of Mutation Some mutations are neutral not good, not bad. Mutations that change the specific proteins needed are usually harmful Some mutations are good! Like those of your who now can digest lactose.