What is the "transformational" molecule in living cells? Right Ans - DNA
How is DNA built? Right Ans - 5' to 3'
What is the structure of DNA? Right Ans - Double Helix
Duchenne Muscular Dystrophy is a genetic disease that leads to muscle
degeneration, paralysis and ultimately early death. It is caused by genetic
errors to the gene dystrophin. When a mother is a carrier of the mutation,
~1/2 of her sons get DMD, while none of her daughters do. Which
chromosome is the dystrophin gene on? Right Ans - X chromosome
Features of hereditary material: Right Ans - 1. Can be replicated
2. Must have info/code necessary to specify structure and function of the
organism
3. Must change over time to allow for evolution
How do we know that DNA is the hereditary material of organisms? Right
Ans - Knowledge of DNA and bacteriophage structure led to evidence that
DNA is genetic material
What experiments led to the conclusion that DNA is hereditary material?
Right Ans - 1. Griffiths
2. Avery, McCarty, MacLeod
3. Hershey, Chase
Describe the Griffiths experiment. Right Ans - Used 2 strains of
pneumococcus, R is not toxic and mice lived when injected, and S is toxic and
mice died when injected. Heat-killed S bacteria injected into mice did not kill
the mice. However, when heat-killed S bacteria were injected along with non-
toxic R, the mice still died. This means that live 'R' bacteria were transformed
and became infectious 'S' bacteria.
Describe the Avery, McCarty, and MacLeod experiment. Right Ans - Same
idea as the Griffiths experiment, but done on plates. Used reverse genetics to
determine what the "transforming agent" was by taking one macromolecule
off the plate at a time to determine whether colonies lived or died.
, Describe the Hershey, Chase experiment. Right Ans - Labeled viruses with
either 32P (blue)or 35S (Red), observed whether proteins or DNA was
transferred to bacterium. Sulfates are only in proteins and Phosphates are
found in DNA, RNA, and proteins.
What experiments contributed to the double-helix model of DNA? Right
Ans - 1. Chargaff
2. Watson and Crick/Franklin, Wilkins & Gosling
Describe the Chargaff experiment. Right Ans - Isolate nucleotides from
various organisms and determine %'s. Hypothesized that A=T=C=G but was
wrong! Actually, A=T and C=G.
Based on Chargaff's work, which of the following is true?
1. The %A in a mouse is approximately equal to the %A in a gorilla
2. %A = %C
3. %A + %C = %T + %G
4. Organisms have equal proportions of A, T, C and G Right Ans - 3. %A +
%C = %T + %G
Describe what Hershey, Chase/ Franklin, Wilkins & Gosling did. Right Ans -
Not an experiment, just rearranged the pieces until they fit.
What they knew:
DNA and RNA are composed of nucleotides
What they assumed:
The chemical reaction between 2 nucleotides
Model they built: Most double-stranded DNA in the cell is B-DNA
What are the key features of a nucleotide? Right Ans - Sugar, base, and
phosphate
Draw a general nucleotide. Right Ans -
Where are the hydrogen bonds in the structure of DNA? Right Ans -
Connecting nucleotides in base pairs
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