Please enable JavaScript.
Coggle requires JavaScript to display documents.
The Molecular Basis of Inheritance - Coggle Diagram
The Molecular Basis of Inheritance
Scientific Inquiry
The role of DNA in heredity was first discovered by studying bacteria and the viruses that infect them
DNA can transform Bacteria
The discovery of the genetic role of DNA began with researched by Frederick Griffith in 1928.
Griffith worked with two strains of a bacterium, one pathogenetic and one harmless
DNA can program cells
DNA as the genetic material came from studies of viruses that infected bacteria
Viruses are called bacteriophages (or phages)
A virus is DNA enclosed by a protective coat, often simply protein
DNA is the Genetic Material
DNA is a polymer of nucleotides, each consisting of a nitrogenous base, a sugar and a phosphate group
The nitrogen bases can be adenine, thymine, guanine, cytosine
Building a Structural Modelo of DNA
After DNA was accepted as the genetic material, the challenge was to determine how its structure accounts for its role in inheritance
DNA replication and repair
Resemblance of offspring to parents relies on accurate replication of DNA prior to meiosis and its transmission to the next generation
Replication prior to mitosis ensures the faithful transmission of genetic information from a parent cell to the two daughter cells
Base pairing to a template strand
Since the two strands of DNA are complementary each strand acts as a template for building a new strand in replication
DNA Replication
The copying of DNA is remarkable in its speed and accuracy. A dozen enzymes and other proteins participate in DNA replication
Getting Started
Replication begins at particular sites called origins of replication, where to two DNA strands are separated, opening up a replication "bubble"
Synthesizing a New DNA Strand
DNA polymerases require a primer to which they can add nucleotides. The initial nucleotide chain is a short RNA primer
Antiparallel Elongation
The antiparallel structure of the double helix affects replication
DNA polymerases add nucleotides only to the free 3 ends of a growing strands so a new DNA strands can elongate only in the 5 to 3 direction
DNA Replication Complex
The proteins that participate in DNA replication form a large complex a DNA "replication machine"
Proofreading and Repairing DNA
DNA polymerases proofread newly made DNA, replacing any incorrect nucleotides
In mismatch repair of DNA repair enzyme replace incorrectly paired nucleotide that have evaded the proofreading process
Replicating the ends of DNA molecules
For linear DNA the usual replication machinery cannot complete the 5 ends of daughter DNA strands