DNA discovery (Phát hiện ADN)

DNA’s Discovery and Structure Honors Objectives SOL.BIO.6f Today’s Objectives:  TSW investigate and understand the common mechanisms of protein synthesis, including the structure of DNA and its discovery. Our Genetic Code  The genetic code is a sequence of nucleotides in the __________ of eukaryotic cells.  There are two polymers of nucleic acids, _____ and ______. Important Scientists that determined DNA’s Importance  Frederick Griffith – bacterial transformation  Oswald Avery – DNA = key to transformation  Alfred Hershey & Martha Chase – Bacteriophage transformation experiment  Erwin Chargaff – base-pairing rules Important Scientists in the “Race for the Double Helix”  Maurice Wilkins & Rosalind Franklin – X-ray diffraction – DNA must be a some type of spiral (helix) – DNA’s diameter is constant and stable  James Watson & Francis Crick – Created the first accurate model of DNA – Won the Nobel Prize DNA’s Structure  DNA is a double helix  DNA contains four nucleotide bases: – adenine (A) – cytosine (C) – guanine (G) – thymine (T) Chargaff’s Rule  The bases form the “rungs” on the DNA ladder by complementary pairing A == T C == G T == A G == C A == T T == A Sugar- phosphate backbone DNA Replication  Replication = Duplication – Happens in the S phase of Interphase – Must replicate before mitosis or meiosis I  Part of the double helix is unwound  Replication in small pieces (Okazaki fragments)  Enzyme stitches pieces together later Semi-Conservative Replication  One-half of each new molecule of DNA is old (template strand)  One-half of new molecule of DNA is new (complementary strand) What is a Gene?  A length of DNA on a chromosome  May be in several parts – Exon – the expressed parts of the DNA sequence – Intron – the intervening, “junk DNA”, not expressed  Parts are cut, put together and then used to make RNA and proteins [...]...Odd Types of Genes  Multigene families  Transposons (Barbara McClintock)  Protective Genes  Viruses may give us new DNA that can be kept over time to cause new evolutionary changes! . – DNA must be a some type of spiral (helix) – DNA s diameter is constant and stable  James Watson & Francis Crick – Created the first accurate model of DNA – Won the Nobel Prize DNA s. Structure  DNA is a double helix  DNA contains four nucleotide bases: – adenine (A) – cytosine (C) – guanine (G) – thymine (T) Chargaff’s Rule  The bases form the “rungs” on the DNA ladder. Replication  One-half of each new molecule of DNA is old (template strand)  One-half of new molecule of DNA is new (complementary strand) What is a Gene?  A length of DNA on a chromosome  May be