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Natural Science
NATS 1610
Barbra Czebhan

Transcription  Bases: Adenine= Uracil, Cytosine= Guanine  Process of releasing info contained in a DNA sequence  Molecules of RNA are assembled on DNA templates in nucleus  Genes are transcribe into 3 RNAs: o Ribosomal: Nucleic acid chain combined with protein to form ribosomes o Messenger: Carries protein- building instructions, delivered to ribosomes o Transfer: RNA molecules serves as an adapter b/w nucleotide sequence of nucleic acids  RNA Polymerase synthesizes an RNA transcript using one strand of DNA as template Translation  Occurs in Ribosomes and cytoplasm  Amino acids are assembled into a chain, the primary structure of a protein o Initiation: tRNA starts transcription loaded onto ribosome subunit o Elongation: Polypeptide chains forms as the mRNA strand passes between ribosome subunits o Termination: Stop codon in the mRNA, enzymes detach and new chain start from ribosomes Genes  Region of a DNA molecule containing a sequence of basis that is transcribed into a functional product o Regulatory Region: Controls initiation of transcription o Coding Region: Bases read into functional molecules o Termination Region: Stops transcription Protein  Organic compounds built of one or more chains of amino acids  Building blocks of cells and tissues in bone and muscles  Major classes of protein: o Enzymatic: Catalyst in biochemical o Regulatory: Control of gene expression o Structural: Cellular of organismal anatomy  Polyribosomes o Strings of ribosomes o Increase the rate of protein production Amino Acids  Building blocks of protein DNA  Transmission of info from one generation to the next  Nucleotides are monomers  2 DNA strands running opposite o Held by base pairs (Adenine=Thymine, Cytosine= Guanine)  Built of a five-carbon sugar, phosphate group, and nitrogen-containing base  The amount of adenine equals the amount of thymine  The amount of guanine equals the amount of cytosine DNA Replication  Copying of DNA before cell division  Polymerase unwinds strands o Old strands serve as templates  Based positioned on each old strands are joined by new strands, linked by hydrogen bonding DNA Repair  Incorporation of incorrect base during DNA rep  Spontaneous changes are immediately corrected  Damage to DNA repair is required by removal of damaged bases, followed by resynthesize of excised region Mutation  DNA undergoes frequent chemical changes  A failure of DNA repair  Quickly repaired Molecular Basis of Mutation  Any change in DNA sequence  Proteins produced by genotype, phenotype Point Mutation  Change in single nucleotide o Errors in DNA replication o Exposure to mutagenic toxins Silent Mutations  Do not change amino acids sequence of a protein Missense Mutation  Change in amino acids sequence of protein Non-sense Mutation  Point mutation that creates new stop codon Frameshift Mutation  Insertion of deletion of 1 or 2 nucleotide o Likely to create new triplet of nucleotide Consequences of Mutation  Protein is reduced  Cancer  Selective Advantage
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