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Chapter 13 (Pgs 360-389 Miller and Levine Biology text) http://www.youtube.com/watch?v=suN- sV0cT6c

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MITOSIS AND MEIOSIS

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DNA mRNA tRNA PROTEIN Transcription Translation

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DNA Nucleotides = deoxyribose sugar Double helix structure Stays inside nucleus RNA Nuleotides = ribose sugar Single-strand structure Located both inside and outside of nucleus Uracil instead of thymine

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A Closer Look at RNA: Contains ribose sugar instead of deoxyribose sugar Single stranded The nucleotide uracil replaces thymine

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3 Types of RNA Messenger RNA = mRNA -Carries genetic coded message sequence from DNA, in the nucleus to the ribosome in the cytoplasm. Ribosomal RNA = rRNA - One of components of the ribosome, rRNA associates with protein to form the ribosome. There are 1000s of ribosomes/cell. -Ribosomal RNA (rRNA) is part of the ribosome. rRNA consists of two subunits that are made up of several ribosomal RNA. Proteins are assembled on the ribosomes. Transfer RNA = tRNA - Transfer RNA (tRNA) transfers each amino acid to the ribosome as it is specified by the coded messages in mRNA. Transfer RNA carries amino acids to the ribosome and matches them to the coded mRNA message. There is one specific tRNA for each amino acid.

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http://www.youtube.com/watch?v=NJxobgkPEAo

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mRNA stands for messenger RNA it is the copy of the DNA message for making a protein Occurs in the nucleus Promoter region on DNA marks where transcription should start and terminator region marks where it should stop

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Basic Principles of Transcription and Translation Transcription Is the synthesis of RNA under the direction of DNA Produces messenger RNA (mRNA) In transcription, segments of DNA serve as templates to produce complementary RNA molecules. In eukaryotes, RNA is produced in the cells nucleus and then moves to the cytoplasm.

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Transcription requires an enzyme known as RNA polymerase. RNA polymerase Binds to DNA during transcription and separates the DNA strands. It uses one strand of DNA as a template to create a complementary strand of RNA.

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RNA polymerase only binds to promoters, which are regions of DNA that have specific base sequences. Before it becomes mRNA, it is called pre- mRNA. Pre-mRNA molecules have bits and pieces cut out of them before they can go into action. The portions that are cut out are called introns. The remaining pieces, known as exons, are then spliced back together to form the final mRNA.

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1. Introns-DNA sequences present in some genes that transcribed BUT are removed during processing and therefore are not present in mRNA. 2. Exons-DNA sequence that are transcribed and joined to other exons during mRNA processing and are translated into amino acid sequence of a protein

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Eukaryotic cell. The nucleus provides a separate compartment for transcription. The original RNA transcript, called pre-mRNA, is processed in various ways before leaving the nucleus as mRNA. (b) TRANSCRIPTION RNA PROCESSING TRANSLATION mRNA DNA Pre-mRNA Polypeptide Ribosome Nuclear envelope In eukaryotes RNA transcripts are modified before becoming true mRNA

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No T (thymine) so when it reads the nucleotide A on DNA it matches it with ____?

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DNA contains all the information for your traits the genes These genes are blueprints and need to remain safe kept inside the nucleus Copies can be made though a messenger http://www.youtube.com/watch?v=NJxobgk PEAo http://www.youtube.com/watch?v=NJxobgk PEAo

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Proteins are made by joining amino acids together into long chains called polypeptides. 20 different amino acids are commonly found in polypeptides. RNA contains four different bases: Adenine, cytosine, guanine, and uracil.

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The genetic code is read three letters at a time, so that each words is three bases long and corresponds to a single amino acid. Each three letter word is called a codon.

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Most amino acids can be specified by more than one codon. UUA, UUG, CUU, CUC, CUA, and CUG all code for leucine. Its time to code! Look at page 367 of your book and follow the steps in figure 13-6.

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The start (initiation) codon for protein synthesis is AUG, which codes for the amino acid, methionine. mRNA continues to be read, three bases at a time, until it reaches a stop codon. This ends translation and the polypeptide is complete.

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If given the following DNA sequence, determine the mRNA sequence transcribed for this gene. Then determine the amino acid sequence of the polypeptide using the codon chart. DNA: T A C A A G T C C A C A A T C

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DNA: T A C G A C A A G T C C A C A A T C mRNA: A U G C U G U U C AGG UG UU A G Leucine-phenylalanine-arginine-cysteine- stop. Wait, why did we stop? STOP codons: UAA, UAG, UGA

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mRNA gives instructions on the order in which amino acids should be joined to produce a polypeptide. Ribosomes use the sequence of codons in mRNA to assemble amino acids into polypeptide chains. Translation is the process of decoding an mRNA message into a protein.

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Transcription is carried on in the cells nucleus. Translation is carried out by ribosomes after the transcribed mRNA enters the cells cytoplasm.

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1. Translation begins when a ribosome attaches to an mRNA molecule in the cytoplasm. 2. tRNA brings the proper amino acid into the ribosome. One at a time, the ribosome attaches these amino acids to the growing chain.

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Each tRNA molecule carries just one kind of amino acid and it contains three unpaired bases. These are called the anticodon. HOLD UP Mrs. Wald. WHAT?! A codon and an anticodon? Please explain.

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TRANSCRIPTION TRANSLATION DNA mRNA Ribosome Polypeptide Amino acids tRNA with amino acid attached Ribosome tRNA Anticodon mRNA Trp Phe Gly A G C A AA C C G U G GUUU GG C Codons 5 3 Molecules of tRNA are not all identical 1. Each carries a specific amino acid on one end 2. Each has an anticodon on the other end

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If you are provided the codon: AUG The anticodon (which is located on tRNA) is: UAC Great, so whats the amino acid? Do you use AUG or UAC? You use the codon, so AUG, which codes for the amino acid methionine.

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3. The ribosome joins the amino acids in the binding sites and tRNA floats away from the ribosome. This creates a peptide chain! 4. The process continues until the ribosome reaches one of three of the stop condons.

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All three forms of RNA come together during translation. mRNA carries the coded message. tRNA delivers the correct amino acid. Ribosomes are composed of roughly 80 proteins and 3 or 4 rRNA molecules. rRNA helps hold ribosomal proteins in place and locate the beginning of the mRNA message.

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Proteins have everything to do with traits! The central dogma of molecular biology is that information is transferred from DNA to RNA to protein.

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Transcribes DNA message and carries it to ribosome RNA polymerse is the enzyme that produces it CLICK ON PICTURE FOR ANIMATION ON TRANSCRIPTION

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Once mRNA is made it attaches to a ribosome tRNA = transfer RNA and they carry amino acids Amino acids are the building blocks of proteins (remember?)

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During transcription The gene determines the sequence of bases along the length of an mRNA molecule DNA molecule Gene 1 Gene 2 Gene 3 DNA strand (template) TRANSCRIPTION mRNA Protein TRANSLATION Amino acid ACC AAACCGAG T UGG U UU G GC UC A Trp Phe Gly Ser Codon 3 5 3 5

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RNA DNA RNA polymerase Section 12-3 Adenine (DNA and RNA) Cystosine (DNA and RNA) Guanine(DNA and RNA) Thymine (DNA only) Uracil (RNA only)

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From the DNA sequence below, write the complementary DNA sequence: TGA TTT CGG TAC GAT TAA CAA CCT CGA ATT ACT AAA GCC ATG CTA ATT GTT GGT GCT TAA If the top DNA strand encodes the message to make a protein, then what will the transcribed M-RNA be: ACU AAA GCC AUG CUA AUU GUU GGA GAU UAA

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A tRNA molecule Consists of a single RNA strand that is only about 80 nucleotides long Is roughly L-shaped Two-dimensional structure. The four base-paired regions and three loops are characteristic of all tRNAs, as is the base sequence of the amino acid attachment site at the 3 end. The anticodon triplet is unique to each tRNA type. (The asterisks mark bases that have been chemically modified, a characteristic of tRNA.) (a) 3 C C A C G C U U A A G ACA C C U * G C * * G UGU * C U * GA G G U * * A * A A G U C A G A C C * C GA G A G G G * * G A C U C * A U U U A G G C G 5 Amino acid attachment site Hydrogen bonds Anticodon A

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Molecular Components of Translation A cell translates an mRNA message into protein With the help of transfer RNA (tRNA) http://highered.mcgraw- hill.com/sites/dl/free/0072437316/12006 0/ravenanimation.html

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Molecular Components of Transcription RNA synthesis Is catalyzed by RNA polymerase, which pries the DNA strands apart and hooks together the RNA nucleotides Follows the same base-pairing rules as DNA, except that in RNA, uracil substitutes for thymine

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DNARNA Nucleotide Deoxyribose Ribose Single-stranded Double-stranded Nitrogenous bases X X X X X X X X

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DNARNA Thymine Uracil Template for synthesis of nucleic acid Double helix Replication Transcription X X X X X X X

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DNARNA Exact Copy Messenger More Than 1 Form Found in Nucleus Leaves Nucleus Does not Leave X X X X X X X

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