Exam (elaborations)
BCH 5413 Exam 1 questions well answered
- Course
- Institution
BCH 5413 Exam 1 questions well answered
[Show more]
Content preview
BCH 5413 Exam 1The number of bases per turn of DNA is___________ - correct answer ✔✔~10.5
What does the Meselson and Stahl experiment confirm? - correct answer ✔✔DNA replication is semi-
conservative
Heavy and light strands with nitrogen isotopes prove
True or False
a. Most biological DNA is positively supercoiled.
b. Triplex DNA is pyrimidine rich
c. Chargaff's rule: A=G & T=C
d. A single zinc finger can recognize 10bp of DNA - correct answer ✔✔A. False, negatively = Left-handed.
Some is right handed = positive
B. True
C. False A=T C=G
D. False, 3 bp, use multiple zinc fingers in a row for more sequence specificity/bp
DNA is not a uniform structure, many localized variants
can substitute protein domains, alpha helix/beta hairpin, in zinc fingers to make hybrids with different
binding specificities (designated by alpha helix) for major grooves of DNA
x-ray crystallography allows us to view and design custom designer DNA-binding proteins = alter gene fxn
in intact cells
In A & Z DNA:
a. Which is right handed helix?
,b. Which one has 12bp per helical turn?
c. Which is the dehydrated form? - correct answer ✔✔a. A
b. Z
c. A
primary DNA is B
Gel electrophoresis - correct answer ✔✔molecular separation technique
can separate nucleic acids or proteins
make AGAROSE gel with slots
hot liquid poured with "teeth"
put DNA in slot, run electric current at neutral pH
DNA = negatively charged (phosphates) = migrates towards positive end
key is friction
DNA stained with fluorescent dye, looked at under UV
unknown DNA electrophoresed parallel with known to determine size
distance migrated = can plot on graph with log of molecular weights or number of bp
ex: 20mm = 910bp
PFGE = Pulsed Field Gel Electrophoresis - correct answer ✔✔for longer sequences
,as large as some chromosomes in yeast
What is PAGE? - correct answer ✔✔Polyacrylamide Gel Electrophoresis
used for PROTEINS
have to denature the protein = treat with detergent, SDS, sodium dodecyl sulfate
SDS-PAGE
SDS advantages:
1) coats polypeptides with (-) charge
2) masks natural charge so results are purely based on molecular weight
What is 2-D gel electrophoresis? - correct answer ✔✔LESS POWER: use two different pH values to
compare, pH affects net charge so different rates of mobility
2-D = 1) proteins electrophoresed through narrow tube gel with pH gradients by ampholytes. Once
protein becomes neutral, no longer moves = isoelectric point
2) gel removed from tube, placed at top of regular gel for SDS-PAGE
What is Ion-Exchange Chromatography? - correct answer ✔✔uses a resin to separate substances
according to charge
(+) charged DEAE-Sephadex for anion-exchange
(-) charged phosphocellulose for cation-exchange
even though most proteins negative, center is positive so can still bind cation-exchange resin
, What is Gel Filtration Chromatography? - correct answer ✔✔after both anion and cation-exchange
chromatography, can target different property of proteins = protein size
pass a solution through a "whiffle ball" with varying size holes
small proteins get stuck, large pass around and go further
What is Affinity Chromatography? - correct answer ✔✔Takes advantage of the affinity of different
proteins to certain ligands.
A ligand or other molecule that binds to a protein of interest is covalently attached to the beads in the
column.
protein of interest eluted from column with a solution that disrupts specific binding
elute = remove
supernatant = remaining solution
What is autoradiography? - correct answer ✔✔A process where radiation from a substance is captured
on a camera.
X-ray of gel electrophoresis
What is a densitometer? - correct answer ✔✔A device for measuring the radioactivity in a fragment of
DNA
the darker and denser the band, the more concentration, absorbance
What do labeled tracers do? - correct answer ✔✔detect tiny quantities of nucleic acids or proteins
The benefits of buying summaries with Stuvia:
Guaranteed quality through customer reviews
Stuvia customers have reviewed more than 700,000 summaries. This how you know that you are buying the best documents.
Quick and easy check-out
You can quickly pay through credit card or Stuvia-credit for the summaries. There is no membership needed.
Focus on what matters
Your fellow students write the study notes themselves, which is why the documents are always reliable and up-to-date. This ensures you quickly get to the core!
Frequently asked questions
What do I get when I buy this document?
You get a PDF, available immediately after your purchase. The purchased document is accessible anytime, anywhere and indefinitely through your profile.
Satisfaction guarantee: how does it work?
Our satisfaction guarantee ensures that you always find a study document that suits you well. You fill out a form, and our customer service team takes care of the rest.
Who am I buying these notes from?
Stuvia is a marketplace, so you are not buying this document from us, but from seller Sakayobako30. Stuvia facilitates payment to the seller.
Will I be stuck with a subscription?
No, you only buy these notes for $19.99. You're not tied to anything after your purchase.
Can Stuvia be trusted?
4.6 stars on Google & Trustpilot (+1000 reviews)
83507 documents were sold in the last 30 days
Founded in 2010, the go-to place to buy study notes for 14 years now