Chapter 12: DNA Structure, Replication and Organization Flashcards
Bacteriophages
A virus that parasitizes a bacterium by infecting it and reproducing inside it.
Nucleotide
Composed of nitrogenous bases. Nucleotides form the basic structural unit of nucleic acids such as DNA.
Deoxyribose sugar
The sugar component of DNA, phosphates that form the chains.
Nitrogenous base
A nitrogen containing molecule that has the same chemical properties as a base. They are particularly important since they make up the building blocks of DNA and RNA: adenine, guanine, cytosine, thymine and uracil.
Purine (adenine and guanine)
A substituted derivative of this, especially the bases adenine and guanine present in DNA and RNA.
Pyrimidine (thymine and cytosine)
A substituted derivative of this, especially the bases thymine and cytosine present in DNA.
Sugar-phosphate backbone
The nucleotides are joined to one another in a chain by covalent bonds between the sugar of one nucleotide and the phosphate of the next, resulting in an alternating sugar-phosphate backbone.
Phosphodiester bond
Links nucleotides together
5’ end
attaches to a phosphate group
3’ end
attaches to a hydroxyl group
Double-helix model
Discovered by Watson and Crick. Anti-parallel DNA strands wind around each other, with purine and pyrimidine bases facing each other in the interior of the molecule.
Why are the DNA strands Antiparallel?
The DNA strands are antiparallel to allow for complimentary base pairing.
Complementary base pairing
Adenines pair with Thymines and Guanines pair with Cytosines.
Semiconservative replication model
DNA replication produces DNA molecules with 1 parental strand and 1 newly made strand (Watson and Crick).
Conservative replication model
DNA replication produces 1 double helix with both parental strands, and the other with 2 new daughter strands.