Nucleic Acids RNA

What are RNA? Nucleic acid polymer of nucleotide monomers Plays role in translation of genetic information from DNA to protein products Acts as messenger between DNA and Protein synthesis complexes (ribosomes) Forms vital portions of ribosomes Carrier molecule for amino acids to be used in protein synthesis

What does she look like? Ribose and phosphate backbone bonded by phosphodiesters 4 different bases-A, G, C and U Uracil replaces Thymine usually a single strand, not a helix 5 carbon sugar-ribose **hydroxyl groups make the RNA less stable than DNA..hot

characteristicDNARNA lengthDNA is longer than RNA, because it stores all the genetic information. RNA is short because it carries one gene at a time. Number of strands twoone location in cellNucleus - it is too big to go through the nuclear membrane. Nucleus and cytoplasm; can travel any where

CharacteristicDNARNA Nitrogenous bases A, T, C, GA, U, C, G SugarsDeoxyriboseRibose How is it madeDNA replicationTranscription

Mirror mirror on the wall……..

Protein synthesis ProcessSiteMajor Component s Notes TranscriptionNucleusDNA gene RNA polymerase Gene is activated. A copy of the code is made from RNA (m-RNA) m-RNA leaves the nucleus, goes to cytoplasm.

Protein synthesis ProcessSiteMajor component s Notes TranslationIn the cytoplasm, on the ribosomes m-RNA Ribosomes Peptidyl transferase enzyme Transfer RNAs Ribosome decodes the m-RNA and makes the correct protein

What’s cooking? The main copy of the genes is in the nucleus to protects it from damage. During protein synthesis, the DNA code is transferred into a working copy made of messenger RNA (transcription) -DNA double helix is unwound Genes are transcribed one at a time The m-RNA leaves the nucleus and translation takes place in the cytoplasm, on the ribosome

The enzymes progress along the template strand in the 3’-5’ direction synthesizing a complementary RNA molecule with elongation in the 5’-3’ direction Some RNA-dependent RNA polymerases use RNA as their template for synthesis of the new RNA strand e.g. poliovirus (RNA virus) ….still cooking RNA

3 Types of RNA are Involved in Protein Synthesis Messenger RNAm-RNAAn RNA copy of a gene Carries information from the DNA to the ribosomes. Ribosomal RNAr-RNA catalytic components of the ribosomes; also includes the enzyme peptidyl transferase (makes peptide bonds) 4 diff RNA-18S, 5.8S,28S,5S

rRNA Make up 80% of the RNA molecules In the cytoplasm, rRNA and Protein combine to form a nucleoprotein- Ribosome Ribosome binds mRNA and carries out protein synthesis. Non-coding RNA are RNA genes that encode RNA not translated to proteins e.g. tRNA and rRNA both involved in translation

Transfer RNA About nucleotides t-RNATransfer amino acids to ribosome to form a polypeptide chain have anticodons which match the m-RNA codons.

The transcribed code is carried from the nucleus to the ribosomes by messenger RNA (m-RNA) The ribosomes contain ribosomal RNA (r- RNA). This type is structural and also acts as an enzyme when the protein is lengthened Transfer RNA (t-RNA) carries amino acids to the ribosomes: there must be at least 20 types of t-RNA

Decoding (translation) occurs on the ribosome Ribosomes are constructed of a special RNA (r-RNA) and protein They have 2 sub-units which come together to form a decoding machine Some ribosomes attached to membranes (rough endoplasmic reticulum), others not attached (free ribosomes) Teach teacher…. Um no! TRANSLATE to amino acids

m-RNA leaves the nucleus and looks for a Ribosome RNA leaves the nucleus and carries the code into the cytoplasm, then attaches to a ribosome

De-coding The RNA Code is Translated into Protein Ribosome finds start codon (AUG), then decodes the message, 3 bases at a time When the ribosome reaches the stop codon the protein is released and the decoding can start over to make another protein

In Translation Amino Acids are Carried to the Ribosomes by Transfer RNA There are at least 20 kinds of t-RNA because there are 20 different amino acids Each transfer RNA has a site that attaches to a specific amino acid, and a site with 3 nucleotide bases (anticodon) that must match up with the RNA code letter for that amino acid Amino acids attach to the new protein only if the t-RNA anticodon matches (is complementary to) the m-RNA codon

Proteins are Finished Off in the Endoplasmic Reticulum & Golgi Apparatus Most new proteins are not immediately functional- they must be finished off In the endoplasmic reticulum and Golgi apparatus they are folded into the proper shape and sometimes chemical groups are added or clipped off Some are routed to the cytoplasm, others to the mitochondria, etc.

…………..recap start1 st codon2 nd codon 3 rd codon DNA code TACAGTCGGGCT m-RNAAUGGCCCGA t-RNA anticodo n UACAGUCGG Amino acid Methioni ne SerineAlanineArginine

DNA synthesizes RNA which in turn makes Protein Many Hormones Act by Turning on Genes certain hormones e.g. sex hormones, cortisone, aldosterone, thyroxine) pass through the cell membrane and enter the nucleus In the nucleus they bind to receptors which turn on genes

Reverse Transcription RNA viruses –Some viruses use RNA instead of DNA as genetic material –One group of RNA viruses, termed retroviruses, convert RNA back to DNA. –RNA viruses make numerous mistakes in replicating genetic information. This means that some viruses like HIV (causes AIDS) changes very rapidly making it difficult to make a vaccine.