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Chapter 9 and 10 DNA: Genetic Material How Proteins are made James Watson and Francis Crick • 1950’s • Used past experiments done by other scientists • Discovered the structure of DNA Characteristics of DNA • Double Helix (twisted staircase) Nucleotides – make up DNA • Subunits • Contain 3 parts: – A phosphate – A sugar- Deoxyribose – Nitrogen base • • • • Adenine (A) Guanine (G) Thiamine (T) Cytosine (C) Nucleotide Pairing • http://www.phsuccessnet.com/iText/pr oducts/0-13-115075-8/index.html • Adenine pairs with thymine • Guanine pairs with cytosine 9-3 Replication of DNA • Occurs during what phase of cell cycle? • Steps: – 2 original DNA stands unzip – Free nucleotides in nucleus are added to each strand – Two identical molecules of DNA are formed. 1. DNA unzips Animation of DNA replication Chapter 10: Making Proteins • What is RNA? – It is a copy of DNA – RNA is used to build proteins – Single stranded – No tymine RNA nucleotides • Ribonucleic Acid • 3 parts: – Sugar: ribose – Single stranded – Nitrogen bases: • • • • Adenine URACIL Cytosine guanine RNA pairings • Adenine pairs with Uracil • Cytosine pairs with Guanine Types of RNA • mRNA – messenger RNA • Made in nucleus, strand shape tRNA – transfer RNA •Found outside nucleus •Carries an amino acid The cell’s alive, it will survive Transcription and translation are how proteins are synthesized Step 1 of Protein synthesis • Transcription – construction of mRNA – DNA strands separate a site of needed protein code. – RNA nucleotides are added to DNA. DNA acts as a template. – mRNA moves out of the nucleus into the cytoplasm to the ribosome Illustration of Transcription Biology: Exploring Life Step 2: Translation • At the ribosome: mRNA is read in groups of 3. • Codon – Group of 3 bases Translation continued • mRNA is read and interpreted • tRNA receives a message to come to the mRNA at ribosome • tRNA carries an amino acid • (anticodon) Translation • This continues until the mRNA is read completely • tRNA attaches to mRNA to attach the amino acid to the protein chain • tRNA them detaches leaving behind its amino acid. • Amino acid will form a protein. Animation of translation Mutations • Changes in the DNA sequence that affect genetic information • Result from changes in a SINGLE gene (not chromosome abnormality) Types of Gene mutations • 1. point mutation – One nucleotide affected – Examples: • Substitution • • Original - The fat cat ate the wee rat. Point Mutation - The fat hat ate the wee rat. Insert example diseases Types of Mutations • 2. Frameshift mutations – one or more bases are inserted or deleted Insertion: • Original- The fat cat ate the wee rat. • Insertion - The fat cat xlw ate the wee rat. • More severe type of mutation Deletion: • The fat cat ate the wee rat. • Deletion - The fat ate the wee rat. Human Genome Project (Collins) • A list of the three billion pairs of human genome (DNA) • An international effort • Completed by the July of 2000 – “working draft” • Great implications in the field of medicine. (Cancer, Immune Disorders, Hemophilia, rheumatoid arthritis) DNA Technology (Science) • Recombinant DNA technology – combining genes from two different organisms to make copies of “good” gene. Steps of Recombinant DNA 1. Cutting DNA using a RESTRICTION ENZYME 2. Inserting the desired gene into a vector • Vector – a bacteria (plasmid) or yeast 3. Cloning of “new DNA” Applications of Recombinant DNA • • • • Agriculture – frost resistant strawberries Industry – clean up oil spills Medicine Food industry – nutrasweet DNA fingerprinting • Useful in forensic science • Useful in medicine Future of medicine • predictive genetic tests for common conditions i.e. cancer • 2020, every tumor will undergo “fingerprinting”, develop drugs to attack the particular gene. Cloning process ex. Dolly The process of making Dolly