The Molecular Basis of Inheritance (2) Flashcards
DNA is a _____ ______ made of ______
Nucleic acid, nucleotides
What bonds form between nucleotides
Hydrogen bonds
How many parts is DNA made of
3
What are the three parts of DNA
Nitrogenous bases phosphate groups and a five carbon sugar
Nitrogenous bases have a chemical like structure that allow them to
Absorb UV light
What are the chemicals in nitrogenous bases that allow them to absorb UV light beneficial for
This allows scientists to measure the amount of DNA by measuring the amount of light it absorbs at a wavelength of 260 nm
Purine
Two ring nitrogenous base
Pyrimidine
One ring nitrogenous base
What bases are purines
Adenine and guanine
What bases are pyrimidines
Cytosine and thymine
Where are the covalent bonds in a DNA molecule
The nucleotides of a strand of DNA are joined by covalent bonds between the sugar one nucleotide and the phosphate group of the next
Chargaff’s rule
Adenine always bonds with thymine and guanine always bonds with cytosine
How did Chargaff create his rule
He discovered his rule because of the percentages of adenine and thymine and guanine and cytosine are always almost identical in any sample of DNA
Rosalind Franklin
Used x-ray diffraction to study the structure of the DNA moleculef
What was Rosalind Franklins job
X-ray crystallographer 
Who did Franklin work under
Wilkins
How did Franklin get a picture of DNA
She purified a large amount of DNA strand of the DNA fiber is in a thin glass tube until they were parallel and shot powerful concentrated x-ray PMs and recorded the scattered patterns of the extras on a film
What does x-ray diffraction pattern reveal
It revealed a helix structure of two strands with nitrogenous bases in the center
Helix
Extended Spiral chain of units in a protein nucleic acid and other macromolecules
James Watson and Francis crick
Made 3-D models of DNA with cardboard and wire by using Franklins x-ray pattern they made a double helix in which two strands of nucleotide sequences were wound around each other
Watson and crick published their work in the paper true or false
True
What was the name of Watsons book
The double helix
The double helix model explains ______ rule and how the two strands of DNA are held together
Chargaff’s rule
Antiparallel
Two strands of DNA run in opposite directions
Nitrogenous bases are hold together by
Hydrogen bonds
Why are the hydrogen bonds between
Nitrogenous bases very important
Because the bond is weak which allows for the DNA to break which is very important for one of its functions
Base pairing
Nearly perfect fit between A and T and G and C
The sides of DNA are made of
Alternating deoxyribose and phosphate
Anti-parallel structure
One strand runs from five prime to three prime in the other runs from three prime to five prime
Meselson-Stahl Experiment
how many hydrogens bonds are between A and T
2
how many hydrogen bonds between G and C
3
meselson - Stahl experiment
put bacteria in nitrogen 15 and then 14 and then centrifuged it once to see if they were the same mass (semi + dispersive stayed) and then centrifuged it again for longer to see if the mass would change and semiconservative worked
