* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download DNA Polymerase
Epitranscriptome wikipedia , lookup
Maurice Wilkins wikipedia , lookup
Cell-penetrating peptide wikipedia , lookup
Eukaryotic transcription wikipedia , lookup
Non-coding RNA wikipedia , lookup
Promoter (genetics) wikipedia , lookup
Protein moonlighting wikipedia , lookup
Community fingerprinting wikipedia , lookup
Gel electrophoresis of nucleic acids wikipedia , lookup
Expanded genetic code wikipedia , lookup
Molecular cloning wikipedia , lookup
Molecular evolution wikipedia , lookup
Transcriptional regulation wikipedia , lookup
DNA vaccination wikipedia , lookup
Silencer (genetics) wikipedia , lookup
Non-coding DNA wikipedia , lookup
DNA supercoil wikipedia , lookup
Genetic code wikipedia , lookup
Biochemistry wikipedia , lookup
Cre-Lox recombination wikipedia , lookup
Point mutation wikipedia , lookup
Gene expression wikipedia , lookup
Vectors in gene therapy wikipedia , lookup
List of types of proteins wikipedia , lookup
Artificial gene synthesis wikipedia , lookup
Chp 12: DNA & Gene Expression 1865 - Mendel 1900 - Morgan - Fruit flies reveal Mendel’s principles 1900 - Garrod - human alkaptonuria follows Mendel’s principle Million $ question, What holds the hereditary information? Morgan proposed chromosomes (colored bodies that occur in pairs) 1928 - Griffith Transformation experiments 1944 - Oswald Avery’s analysis & manipulation of transformation extract (denaturing different organics using enzymes - only extract exposed to DNA destroying enzymes loses ability to transform) 1952 Hershey & Chase Experiments with viruses composed of DNA & protein grown in Sulfur isotopes & Phophorus isotopes - Phosphorus isotopes found in host cell Million $ question - How does DNA carry hereditary info What would scientists likely need to know in order to answer this question? Chemical Composition - Chargaff Nucleotides with nitrogenous bases 4 types of bases Rosalind Franklin - 1952 - X-ray diffraction studies Two stranded chemical Equal distance between two strands 1953 - Watson & Crick Proposal Double Helix - bound at the bases complimentary base pairing maintains width, holds strands together and ultimately establishes a code Nucleotide Phosphate 5 Carbon Sugar Deoxyribose Nitrogenous Base •Adenine •Guanine •Cytosine •Thymine Twist this structure to get a double helix Bases must be readily available to make the nucleotides. Plants assemble the bases from nutrients in the soil. Animals get their nucleotides ready made in what they eat. Inadequate supplies will lead to stunted growth or malnutrition diseases. DNA Replication • • • • Occurs during the S-Phase Involves the action of special enzymes Semi Conservative Makes mitosis possible Enzymes initiate the process •Helicase - breaks bonds between bases •Primase - lays down a short sequence of RNA nucleotides that enables DNA Polymerase to begin replication •DNA Polymerase - organizes complimentary nucleotides in order to assemble a new DNA strand •Ligase - glues open ends of DNA where primers are removed •Binding Proteins maintain single strands Animation Many Replication bubbles can be seen on a Single DNA at once Even at the rate of hundreds of base pairs per second it takes hours to replicate the human genome. (base pairs in the billions) DNA holds code which determines cell function Cell Function determines cell/tissue characteristics Tissue function determines organism characteristics How is the DNA code translated into specific cell function? DNA controls the production of proteins, the types of proteins present or not present determines cell / tissue function (lactose intolerance, hemophilia, sickle cell anemia……) Proteins are composed of long chains of amino acids There are 20 different amino acids. The number, type and Amino Acids sequence in which they are linked together determines the proteins function. Change the sequence, type, or number of amino acids in a protein you change the function. Amino Acids without water sensitive R-groups Interactions between adjacent amino acids produces spiral or pleating Interactions between R-groups forms bends & folds Two or more amino acids chains may hook up to form functional protein Computer modeling enables scientists better understand protein structure The production of protein by DNA involves a two step process and requires the presence of three different types of RNA (all of which are assembled by DNA) The DNA functions as the boss and the RNA as the workers. The code for a particular protein is held by the DNA. RNA converts the code into specific proteins Plants assemble their amino acids from nutrients acquired from the soil. How do animals acquire their amino acids? Biologists believe that RNA was the first information storing chemical used by primitive life forms and that it quickly was replaced by DNA. Why is DNA better at storing information? DNA & RNA are chemically and physically different. It is their difference in chemical and physical properties that enable them to have different functions. DNA Only in the nucleus Double stranded A-T & G-C base pairing Deoxyribose Ribose Sugar RNA Nucleus & cytoplasm Single stranded A-U & G-C base pairing Ribose Sugar Transcription Animation M-RNA T-RNA R-RNA Translation Animation Transcription Complimentary base pairing insures an accurate writing of the code. The use of RNA nucleotides insures that the nucleic acid is to function in the cytoplasm The order of the nucleotides defines its function (m-RNA, t-RNA, r-RNA) Animation Translation: The M-RNA that was made by the DNA leaves the nucleus and associates with R-RNA, T-RNA, and initiator proteins to start the production of protein Animation The M-RNA can have many ribosomes be attached at once (poly ribosomes) Which ribosome has is the most recent to have attached to the M-RNA? M-rna codon calls for a complimentary t-rna anticodon Biologists have deciphered the code of life- m-RNA codon chart To Conserve energy and raw materials, there are several levels of control that insure that gene expression only occurs when needed. 1- DNA Structure can Regulate gene expression 2- Activation or Blocking Promoter Sites 3- M-RNA Processing can regulate gene expression - processing may not begin until key chemical conditions have been established 4- Protein Processing Proteins that are asembled may require specific conditions to be establishjed before they take on their active form. This also helps to regulate gene expression Web Links For DNA/RNA Review