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Deoxyribonucleic Acid. History:. 1. Theory of Evolution : 1859; Darwin. 2. Science of Genetics : 1870; Mendel. 3. Chromosomes Discovered: 1910; T.H. Morgan. 4. DNA discovered : 1953; James Watson, Francis Crick and Rosalind Franklyn. -used Franklyn’s to write their paper
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4. DNA discovered: 1953; James Watson, Francis Crick and Rosalind Franklyn -used Franklyn’s to write their paper -received the Nobel prize in 1962 -used x-ray crystallography to see DNA shape -died at age 38
DNA Structure • Shaped like a twisted ladder • Called double helix
DNA Structure -Nucleotide: monomer of DNA made of a sugar (deoxyribose), a base and a phosphate
Bases of DNA Purines (large bases): -adenine (A) -cytosine (C) Pyrimidines (small bases): -thymine (T) -guanine (G) *Adenine with thymine *Cytosine with Guanine -bonded with weak hydrogen bonds
Nucleic Acid Processes: • Replication: DNA copying and making new DNA • Transcription: DNA making RNA • Translation: RNA synthesizes proteins
DNA Replication -cell divide and must replicate DNA -happens before mitosis 3 Steps: • The enzyme helicase moves over DNA and unzips it at the hydrogen bonds • DNA polymerase (enzyme) moves along the exposed strand and adds the complimentary nucleotide • Two daughter strands are formed
DNA Replication • One mistake for every 10,000 base pairs • Mutation: a change in nucleotide sequence • Not always bad; some good; most neutral
DNA vs. RNA Comparison DNA • FX: stores genetic information • Double helix structure • Base: A, C, G, and T • Sugar: deoxyribose RNA • FX: synthesizes proteins • Single helix structure • A,C,G, and Uracil • Sugar: ribose
Three Types of RNA 1. Messenger RNA (mRNA): provides the code for amino acids • Transfer RNA (tRNA): carries amino acids to ribosome • Ribosomal RNA (rRNA): unknown function
Transcription: DNA makes RNA 4 Steps: • RNA polymerase opens DNA and adds complimentary RNA nucleotides to the DNA • RNA reaches a “stop” sequence • mRNA leaves the nucleus to build proteins
Translation: protein synthesis Protein: What are they? -amino acids are the monomers -20 different amino acids -peptide bonds between amino acids -codon: a three base code on mRNA that codes for amino acids -each codon is specific for an amino acid
Decode the following strand of DNA in mRNA then into a protein Protein: “START”-Phe – Asn – Ala – Thr – His – “stop” mRNA: AUG UUU AAC GCU ACA CAC UAA DNA: TAC AAA TTG CGA TGT GTG ATT
Translation: Steps • mRNA leaves the nucleus, enters cytoplasm, attaches to a ribosome. • tRNA attaches to the mRNA with an “anticodon”, carrying an amino acid • Amino acid attaches to a ribosome and starts the protein. tRNA leaves to get a new amino acid • Ribosome moves down the mRNA picking up a new amino acid at each codon. • Reaches the stop codon and ends translation • Protein is released for a metabolic process.
The Genome: - The totality of DNA base pairs in the cells of a species -exact sequence of DNA bases • All the ACTGs on each chomosome • One of the greatest discoveries of all time
Sequenced Genomes • Human • Chimpanzee • Rice • Malaria parasite • E. coli • Lab mouse • Drosophila melanogaster
National Genome Project • Director: Francis Collins • “blue print” of human body: the “holy grail” • 12 year project • Fully funded by U.S. Government • Life changing
How it will change our lives: - Gene screening at an early age • Know diseases in advance • Designer drugs • Design babies • Genetic counselors • Lifespan expanded • Genetically modified organisms
Genome is the future of medicine • Pre-treat disease and illness before it manifests itself • Changed our legal system, medical science, understanding evolution
Polymerase Chain Reaction • Process of amplifying a sample of DNA • Uses: criminal convictions, ID human remains, new species, taxonomy, evolution
Gel Electrophoresis: DNA fingerprinting • DNA is put into a gel • Stained with methyl or violet • Moved through gel with electricity • Separate by size • The more matching bands the more likely a sample and an unknown are related