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Nucleic Acids and Protein Synthesis Nucleic Acids DNA Deoxyribonucleic Acid RNA Ribonucleic Acid DNA Double stranded helix Never leaves the nucleus Watson, Crick, Wilkins won Nobel Prize in 1962 Franklin died in 1958 never recognized DNA Nucleotide Building Blocks of nucleic acids are NUCLEOTIDES! Phospate group Sugar molecule (deoyribose) Nitrogenous bases Nitrogenous Bases of DNA How do the N-Bases pair up? A-T (2 bonds) G-C (3 bonds) How Does DNA Replicate? 1. double helix unwinds 2. Each chain serves as a template for new nucleoide chain 3. point at which 2 chains separate is called the REPLICATION FORK. 4. HELICASE = the enzyme that separates the chains (breaks H bonds) 5. DNA POLYMERASE moves along the chains and helps assemble new nucelotides forming new chains (3’ to 5’ ONLY) DNA LIGASE – ligates 5’ to 3’ (DNA polymerase brings the nucleotides) DNA replication continue… The 3’ sugar has an –OH GROUP The 5’ sugar has a PHOSPHATE GROUP LEADING STRAND – formed from 3’-5’ LAGGING STRAND – formed from 5’- 3’ with the help of DNA LIGASE! OKAZAKI FRAGMENTS – fragments that will be ligated together Can you see how DNA is making an exact copy of itself! * This a little more difficult Can you figure out the diagram? Simplest Illustration of DNA replication… What is a mutation?? A CHANGE in the nucleotide sequence at even ONE location!! RNA RIBONUCLEIC ACID SINGLE STRANDED RESPONSIBLE FOR BRINGING THE GENETIC INFO. FROM THE NUCLEUS TO THE CYTOSOL! RNA Nucleotide Phosphate group Sugar molecule (ribose) Nitrogenous bases Adenine – URACIL Cytosine - guanine 3 Kinds of RNA mRNA – (messenger) brings info from DNA in nucleus to cytosol in eukaryotic cells (uncoiled) tRNA –(transfer) brings amino acids to mRNA for translation (hairpin shape) rRNA –(ribosomal) most abundant, rRNA makes up the ribosomes where proteins are made (globular) TRANSCRIPTION!! DNA RNA 1.RNA polymerase-initiates transcription by binding to region on DNA called PROMOTER (causes DNA to separate) 2. only ONE of the DNA chains will be used for transcription it’s call the TEMPLATE 3. RNA POLYMERASE – attached to first DNA nucleotide of template chain – then begins adding complementary RNA nucleotides Cont. Transcription 4. transcription continues until RNA polymerase reaches a TERMINATION SIGNAL on the DNA 5. RNA polymerase releases both the DNA mol. And newly formed RNA mol. Are transcribed in this way (all three!!!) RNA * RNA replications Protein Synthesis PROTEINS CARRY OUT THE GENETIC INSTRUCTIONS ENCODED IN AN ORGANISM’S DNA!!!! TRANSLATION The process of assembling from info. Encoded in a mRNA! 1. mRNA leaves nucleus 2. mRNA migrates to ribosome in cytosol for protein synthesis 3.amino acids floating in cytosol are transported to ribosomes by tRNA mole 4. peptide bonds join the amino acids to make polypeptide chain Vocabulary! 1. GENETIC CODE: correlation between a nucleotide sequence and an amino acid sequence 2. CODON 3 mRNA nucleotides, codes for a specific amino acid (64) 3. START CODON (AUG) & a.a. methionine 4. STOP CODON (UAA, UAG, UGA) 5. ANTICODON – 3 tRNA nucleotides carrying a specific amino acid! Protein Synthesis * Protein Synthesis * Protein Synthesis ! THE SUMMARY!