Bch5413 Exam 1 Updated Actual Questions And Correct Answers

BCH5413 EXAM 1 UPDATED ACTUAL QUESTIONS AND
CORRECT ANSWERS

Question:
1. In the experiment described that supports DNA as the
genetic material:
a.
Why does the mouse die if the researcher mixes the
completely dead pathogenic strain with live non-
pathogenic strain bacteria and then injects it into the
mouse? (The first mouse in the figure).

Answer:
- R strain has been transformed = now S strain
---- can produce virulence factors that make the S strain deadly to mice.
-- pathogenic strain is killed, its DNA is released, and now floating freely can go
into the R strain and TRANSFORM it.

Question:
1. In the experiment described that supports DNA as the
genetic material:
b.
What was the only scenario in which the mouse lives?
Why?

Answer:
-- When DNA of the S strain was destroyed
-- DNA that caused the virulence factors is destroyed = no function

Question:
2. What were the contributions of Wilkins, Franklin,
Watson, and Crick to the discovery of the structure of
DNA?

Answer:
Wilkins + Franklin = crystal X pattern of helix
Watson + Crick = model of DNA structure

Question:
3. Based on the carbon numbering system for the sugar (1
- 5) that makes up DNA, describe the main component
that is attached to each carbon and why it is important to
the structure of DNA.

Answer:
The next 5 questions are for this...

,Question:
3. In DNA, C1 is bonded to...
This is important because...

Answer:
-- a nitrogenous base (adenine, guanine, cytosine, or thymine)
-- this allows the nitrogenous bases to form hydrogen bonds
-- A-T
-- C-G
between the 5`-3` strand and the 3`-5` strand

Question:
3. In DNA, C2 is bonded to...
This is important because...

Answer:
H
Importance - C2 does not have a hydroxyl group, which distinguishes it from RNA.

Question:
3. In DNA, C3 is bonded to...
This is important because...

Answer:
OH
Importance - The C3 of one sugar forms a phosphodiester bond with the 5`
phosphate of another sugar.
--- makes phosphodiester chain

Question:
4. In DNA, C4 is bonded to...

Answer:
C5

Question:
5. In DNA, C5 is bonded to...
This is important because...

Answer:
phosphate
Importance - The C5 can be the lead sugar or form phosphodiester bonds with
the C3 of a second sugar.
-- This gives DNA the 5` to 3` linkage.

, Question:
4. Describe why DNA has directionality.

Answer:
-- 5' end = free phosphate group
-- 3' end = free hydroxyl (OH) group
-- DNA is always synthesized in the 5'-to-3' direction = added only to the 3' end of
the growing strand
-- G forms 3 hydrogen bonds to C
-- A forms 2 hydrogen bonds to T
-- Sequence of DNA has an effect on the structure.

Question:
5. What is the meaning of the term antiparallel in the
structure of DNA?

Answer:
-- orientation is opposite
-- 5' - 3' polarities are in opposite directions

Question:
6. What does the Meselson and Stahl experiment
confirm?

Answer:
-- complementary base pairing allows us to move that information to the next
generation of DNA
-- semi-conservative model

Question:
7. True/False:
a.
The major groove is the structure of DNA that allows for
more specificity in binding proteins

Answer:
TRUE
-- minor groove = less specific

Question:
7. True/ False:
b.
Eukaryotic DNA in nucleus of cells will not supercoil since
it is linear

Answer:
FALSE
-- linear + circular DNA can supercoil