Chapter 16
The amount A is always equivalent to T, and C to G.
Chargaffs analysis of the relative base composition of DNA was good because..?
Sequence of bases
Could carry out a vast amount of heredity information?
12
Cytosine makes up 38%. What percentage will be thymine?
A+C=G+T
In nucleotide composition, which will be found?
Griffith, Avery, McCarty, and MacLeod, Hershey and Chase, Watson and Crick, and Meselson and Stahl
Which scientists made significant contributions to our understanding and function of DNA.
Descendants of the living cells are also phosphorescent.
After mixing a heat-killed, phosphorescent strain of bacteria with a living non-phosphorescent strain, you discover that some of the living cells are now phosphorescent. Which observations would provide the best evidence that the ability to fluoresce is a heritable trait?
Proteins have a greater variety of three-dimensional forms than does DNA.
For a couple of decades biologists knew the nucleus contained DNA and proteins. The prevailing opinion was that the genetic material was proteins, and not DNA. The reason for this belief was that proteins are more complex than DNA. What was the basis of this thinking?
Amino acids (and thus proteins) also have nitrogen atoms; thus, the radioactivity would not distinguish between DNA and proteins.
For a science fair project, two students decided to repeat the Hershey and Chase experiment., with modifications. They decided to label the nitrogen of the DNA, rather than the phosphate. They reasoned that each nucleotide has only one phosphate and two to five nitrogens. Thus, labeling the nitrogens would provide a stronger signal than labeling the phosphates. Why wont this experiment work?
Mixing a heat-killed pathogenic strain of bacteria with a living nonpathogenic strain can convert some of the living cells into the pathogenic form.
In his transformation experiments, what did Griffith observe?
DNA contains phosphorus, but protein does not.
In trying to determine whether DNA or protein is the genetic material, Hershey and Chase made use of which of the following facts?
Assimilation of external DNA into a cell.
What does transformation involve in bacteria?
the diameter of the helix
What is determined from X-ray diffraction photographs of crystallized DNA?
The viral proteins will be radioactive
When T2 phages infect bacteria and make more viruses in the presence of radioactive sulfur, what is the result?
Hydrogen
Which chemical bond is found between paired bases of the DNA double helix?
Oswald Avery, Maclyn McCarty, and Colin MacLeod
Who is responsible for discovering chemicals from heat-killed S cells were purified. The chemicals were tested for the ability to transform live R cells. Transforming agent=DNA
Alfred Hershey and Martha Chase
Who was responsible for discovering DNA, not protein, entered the bacterial cells, and was therefore concluded to be the genetic material.
Erwin Chargaff
Who was responsible for discovering the amount of A equals the amount of T and the amount of G equals the amount of C.
Purines pair with pyrimidines
Why does the double helix have a uniform diameter?