In 1952 who showed that helix was double and had a uniform diameter of about 2nm?? How was it revealed?
Helical structure was revealed by X ray diffraction.
Discovered by Maurice Wilkins and Rosalind Franklin.
The sugar-phosphate backbone forms the double helix. Discovered by...
Discovered by James Watson and Francis Crick by deduced the structure of DNA.
rungs
the N-containing bases pair up to form rungs' one from each sugar-phosphate backbone.
Charguff's rule
bases are hydrogen-bonded. A-T and G-C
The backbones are
antiparallel. Each strand is directional with a free sugar on one end and a phosphate on other. The directions of the two strands are oppposite, tehy run head to tail.
Information depends on the....
sequence of the necleotides NOT their number.
The small number of nucleotides (4) made many scientists skeptical that DNA was the hereditary molecule.
genetic information occurs in...
codons. Triplets ofbases. With 4 distinct bases, there are 64 possible combinations, which means that they can code for the 20 amino acids, start, stop and a number of other functions.
DNA replication is necessary for cell division and requires...
several enzymes: DNA helicase, DNA polymerase and DNA ligase.
Replication is semiconservative.
How many mistakes does DNA polymerase make?
roughly 1 mistake per 10,000 base pairs= good.
error rate reduced to
1 mistake per billion base pairs by proofreading enzymes. THese enzymes use the complementary DNA strand as a template to repair damage. THey excise (cut out) the mismatch and replace it with correct bases.