Ap Bio Essay Example Biotech
DNA QUESTION 1995: L. PETERSON/AP BIOLOGY
The diagram below shows a segment of DNA with a total length of 4,900 base pairs. The arrows indicate reaction sites for two restriction enzymes (enzyme X and enzyme Y).
(A) Explain how the principles of gel electrophoresis allow for the separation of DNA fragments.
(B) Describe the results you would expect from electrophoretic separation of fragments from the following treatments of the DNA segment above. Assume that the digestion occurred under appropriate conditions and went to completion.
I. DNA digested with only enzyme X
II. DNA digested with only enzyme Y
III. DNA digested with enzyme X and enzyme Y combined
IV. Undigested DNA
(C) Explain both of the following: (1). The mechanism of action of restriction enzymes (2). The different results you would expect if a mutation occurred at the recognition site for enzyme Y.
PART A. Explain how the principles of gel electrophoresis allow for the separation of DNA fragments. (4 points max.)
Electricity..........Electrical potential (charge, field) moves fragments Charge..............Negatively charged fragments move toward (+) anode through gel (-) charge due to phosphate groups Rate/size..........Smaller fragments move faster (farther)relative to larger fragments. Describe logarithmic relationship Calibraton.........DNAs of known molecular weights are used as markers/standards Resolution........Depends on concentration of gel; is determined by pore size Apparatus.........DNA is stained for visualization of bands/explains use of wells, gel material, tracking dye, buffers.
PART B. Describe the results you would expect from electrophoretic separation of fragments from the following treatments of the DNA segment above. (4 points max.)
Treatment I........Describes 400, 1300, 1500, 1700,bp
The diagram below shows a segment of DNA with a total length of 4,900 base pairs. The arrows indicate reaction sites for two restriction enzymes (enzyme X and enzyme Y).
(A) Explain how the principles of gel electrophoresis allow for the separation of DNA fragments.
(B) Describe the results you would expect from electrophoretic separation of fragments from the following treatments of the DNA segment above. Assume that the digestion occurred under appropriate conditions and went to completion.
I. DNA digested with only enzyme X
II. DNA digested with only enzyme Y
III. DNA digested with enzyme X and enzyme Y combined
IV. Undigested DNA
(C) Explain both of the following: (1). The mechanism of action of restriction enzymes (2). The different results you would expect if a mutation occurred at the recognition site for enzyme Y.
PART A. Explain how the principles of gel electrophoresis allow for the separation of DNA fragments. (4 points max.)
Electricity..........Electrical potential (charge, field) moves fragments Charge..............Negatively charged fragments move toward (+) anode through gel (-) charge due to phosphate groups Rate/size..........Smaller fragments move faster (farther)relative to larger fragments. Describe logarithmic relationship Calibraton.........DNAs of known molecular weights are used as markers/standards Resolution........Depends on concentration of gel; is determined by pore size Apparatus.........DNA is stained for visualization of bands/explains use of wells, gel material, tracking dye, buffers.
PART B. Describe the results you would expect from electrophoretic separation of fragments from the following treatments of the DNA segment above. (4 points max.)
Treatment I........Describes 400, 1300, 1500, 1700,bp