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Download EK 3.A.1: DNA, and in some cases rna, is the primary
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EK 3.A.1: DNA, AND IN SOME CASES RNA, IS THE PRIMARY SOURCE OF HERITABLE INFORMATION. DNA Structure, Replication, and Protein synthesis. Genetic Information is transmitted from one generation to the next through DNA or RNA • Genetic Information is stored and passed on through DNA molecules, some cases it is RNA • Rhino Virus-Colds, Flu, hepatitus • Retroviruses-HIV • Special case where flow of information is reversed, RNA to DNA, reverse transcriptase, incorporated into the host DNA where it is transcribed and translated to make new viral particles. • DNA • Polymers of nucleotides • Contained in Chromosomes • Prokaryotes- Circular Chromosomes • Eukaryotes- Linear chromosomes and a single linear DNA molecules • Also can be found in plasmids,small circular pieces of DNA DNA and RNA • Made of nucleotides • Base, Sugar, Phosphate • Polymers with a 3’ and5’ end • Structural Differences • DNA has Deoxyribose sugar • RNA contains uracil in place of thymine • DNA is usually double stranded • DNA two strands are antiparellel. • Base Pairing • Both DNA and RNA A-T (U) and G-C • Purines G and A double rings • Pyrimidines C, T and U and are single rings RNA Structure and Function • mRNA • Carries information from DNA to the Ribosome • tRNA • Attaches to specific Amino Acids • Translation of mRNA into a linear peptide • rRNA • Structural component of Ribosomes Flow of Genetic Information • Bases in a gene to amino acids in a protein • Transcription • RNA polymerase reads DNA 3’ to 5’ and makes mRNA 5’ to 3’ • In Eukaryotes only • mRNA is processed • Poly-A tail • Removal of introns • Translation • Occurs in the cytoplasm of eukaryotes at the ribosome • Prokaryotes, transcription and translation are coupled together Important features of protein synthesis • RNA polymerase binds to promoter sequence in DNA • RNA polymerase makes mRNA • mRNA is processed in eukaryotes • mRNA interacts with the ribosome to initiate translation • At the start codon • Nucleotides on mRNA is read in triplet codons • Codons encode a specific amino acid that can be determined by • • • • • using a genetic code chart. There is redundancy in the code. tRNA brings the correct amino acid to the ribosome mRNA complex. The amino acid is transferred to the growing amino acid chain. Process continues until a stop codon is reached The newly synthesized peptide/protein is then released Further modification of the protein may be needed before it is functional. Phenotypes-How an organism looks • Determined by protein activities • Alkaptonuria- Black urine • Na/K pump and proteins • Pigment production • Wrinkled peas/smooth peas Genetic Engineering Techniques can manipulate genetic information • Transformation using plasmids • Restriction enzymes and DNA analysis • Genetically modified foods • Salmon approved for human consumption • Corn and other crops • Round up Ready seeds • Pharmaceuticals • Insulin/growth factor
