Protein Transcription And Translation Biology 12 PDF

Protein Transcription Biologyand Translation Biology 12 Copyright Pearson Prentice Hall  12–3 RNA and Protein Synthesis Genes are coded DNA instructions that control the production of proteins. Genetic messages f...

Protein Transcription Biologyand Translation Biology 12 Copyright Pearson Prentice Hall  12–3 RNA and Protein Synthesis Genes are coded DNA instructions that control the production of proteins. Genetic messages from our DNA can be decoded by copying part of the nucleotide sequence from DNA into RNA. RNA contains coded information for making proteins. Copyright Pearson Prentice Hall  The Structure of RNA The Structure of RNA There are three main differences between RNA and DNA: The sugar in RNA is ribose instead of deoxyribose. RNA is generally single-stranded. RNA contains uracil in place of thymine. Copyright Pearson Prentice Hall Remember RNA?  Types of RNA Each with a different function – messenger RNA – ribosomal RNA – transfer RNA Copyright Pearson Prentice Hall  Types of RNA Messenger RNA (mRNA) carries copies of instructions for assembling amino acids into proteins. Creates these instructions through the process of transcription Copyright Pearson Prentice Hall Transcription – DNA is copied into the form of RNA – This first process is called transcription. – The process begins at a section of DNA called a promoter. - Promoter is a region of DNA with repeating T’s and A’s. Near 5’ end. - TATA box Copyright Pearson Prentice Hall  Polymerase RNA Polymerase- Enzyme attaches to the Promoter region – Copies the DNA sequence into complementary RNA sequence. RNA sequence is assembled in 5’-3’ direction. RNA made up of 4 bases – Adenine, Uracil, Cytosine, Guanine. Polymerase stops when it encounters a terminator sequence. Copyright Pearson Prentice Hall Copyright Pearson Prentice Hall  Pre mRNA Now you have chain of Pre mRNA – A complementary sequence of the DNA except U has replaced T – It’s called Pre RNA because it’s not ready yet. Need to trim some fat Pre mRNA is made up of sequences called – Introns and Exons Copyright Pearson Prentice Hall  Introns and Exons Introns are regions of non coding DNA Exons are regions of coding DNA Pre mRNA need to remove the Introns before transcription will be complete. – Removes Introns through RNA Splicing – snRNA allow removal of Introns Now you have mRNA that is ready to transmit its message. Copyright Pearson Prentice Hall  Introns and Exons In Summary: snRNP’s cut out Introns and bind Exons together Copyright Pearson Prentice Hall  mRNA Introns are removed, you’re left with strand of mRNA. Now what? mRNA leaves the nucleus via nuclear pore and enters cytoplasm The mRNA needs to translate its message into Protein. Copyright Pearson Prentice Hall Translation Translation Translation is the decoding of an mRNA message into a polypeptide chain (protein). Uses information from messenger RNA to produce proteins. Two organelles involved in the process Nucleus Copyright Pearson Prentice Hall mRNA  Codons Before moving too far need to understand Codons A sequence of 3 nucleotide base mRNA is made sets of three nucleotides called Codons Copyright Pearson Prentice Hall  Ribosomal RNA The ribosome is a cellular machine. – Purpose is to convert instructions of mRNA into chains of amino-acids. – Has two “sites” P and A. – Ribosomal finds the mRNA in the cytoplasm and binds to the “Start Codon” AUG Copyright Pearson Prentice Hall Copyright Pearson Prentice Hall  Transfer RNA Small molecule in cells that carries amino acids to the ribosome – The amino acids are linked into proteins within the ribosome. – Transfer RNA has an anticodon attachment site to allow binding to mRNA. Copyright Pearson Prentice Hall  AntiCodon Copyright Pearson Prentice Hall  Amino Acids Building blocks of proteins Link together via peptide bonds Approximately 20 are essential for protein formation They are put in place by the tRNA molecule through the process of translation. Copyright Pearson Prentice Hall  Put the pieces together We have all three pieces – mRNA, Ribosomal RNA, tRNA – How do we make proteins? 1)Ribosome must attach to mRNA – Start codon must be read AUG 2)tRNA brings in first amino acid – tRNA binds its anti codons to the mRNA codons Copyright Pearson Prentice Hall The ribosome RNA binds new tRNA molecules and amino acids as it moves along the mRNA. Copyright Pearson Prentice Hall  Translation The process continues until the ribosome reaches a stop codon. Polypeptide Ribosome tRNA mRNA Copyright Pearson Prentice Hall  Codon Codon Codon Genes and Proteins DNA Single strand of DNA Codon Codon Codon mRNA mRNA Protein Alanine Arginine Leucine Amino acids within a polypeptide Copyright Pearson Prentice Hall The Genetic Code Copyright Pearson Prentice Hall