You have discovered a very small amount of DNA from an ancient organism that you want to save and study. What is the very first thing you should do to allow you to study this DNA in the lab?
A. RT-PCR
B. Gel electrophoresis
C. Polymerase chain reaction (PCR)
D. Insert the DNA into a vector
Clarify Question
· What is the key concept addressed by the question?
· What type of thinking is required?
· What key words does the question contain and what do they mean?
Gather Content
· What do you already know about DNA techniques?
Consider Possibilities
· Consider the different answer options. Which can you rule out?
Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
C. Polymerase chain reaction (PCR)
Clarify Question
· What is the key concept addressed by the question?
o This question addresses DNA techniques.
· What type of thinking is required?
o This question is asking you to take what you already know and apply it to this unfamiliar situation.
· What key words does the question contain and what do they mean?
o Researchers who study ancient DNA are often trying to get DNA out of fossils or specimens that are extremely old, where most of the DNA is long gone.
Gather Content
· What do you already know about DNA techniques?
o Different DNA techniques allow researchers to take a small amount of DNA and make more, or determine the size of DNA fragments, of match DNA to a particular probe.
o In this case, when you have a vanishingly tiny amount of DNA like that from an ancient sample, the first thing you must do is to amplify it into a larger amount
Consider Possibilities
· Consider the different answer options. Which can you rule out?
o Does Southern blotting amplify DNA? No, it probes DNA to see if it matches another sequence.
o Does gel electrophoresis amplify DNA? No, it sorts DNA fragments by length.
o Does inserting the DNA into a vector amplify the DNA? Yes, this can be a way to amplify DNA. But it is not a good way to amplify very tiny amounts of precious DNA, because most DNA will be lost in the process.
Choose Answer
· Given what you now know, what information and/or problem solving approach is most likely to produce the correct answer?
o Does polymerase chain reaction amplify DNA? Yes! PCR is the best technique for amplify DNA from tiny amounts.
Reflect on Process
· Did your problem-solving process lead you to the correct answer? If not, where did the process break down or lead you astray? How can you revise your approach to produce a more desirable result?
o This question asked what would be the best technique for a tiny amount of DNA.
o The question required you to take what you already know and apply it to this unfamiliar situation.
o Did you recognize that PCR is the best way to amplify small amounts of DNA?
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Which of the following events occur during anaphase I of meiosis?
A. The chromosome number is doubled during this phase of meiosis. B. In females, the two X chromosomes remain together. C. In males, the X chromosome is segregated from the Y chromosome. D. The centromeres of the chromosomes divide. E. Homologous chromosomes move as one unit.
During meiosis, pairs of homologous chromosomes line up at the metaphase plate where they attach to kinetochore microtubules and are drawn to opposite poles of the cell. The selection of chromosomes from each pair is essentially random and accounts for much of the immense variety of traits displayed by sexually reproductive organisms, as illustrated in this diagram. Despite a similar division of genetic material between daughter cells in mitosis, no shuffling of chromosomes occurs. What accounts for this difference between meiosis and mitosis?
a. During mitosis, only a single combination of chromosomes is possible due to a slight polar charge that is absent during meiosis.
b. During mitosis, only a single combination of chromosomes is possible due to enzymes that arrange chromosomes in order.
c. During mitosis, only a single combination of chromosomes is possible because no recombination occurs and the homologs are never separated.
d. During mitosis, only a single combination of chromosomes is possible because nonconforming cells trigger an immune response.
You decide to do an experiment with isolated myofibrils to explore the effects of ATP hydrolysis on myofibril function. You do this by bathing the myofibrils in a solution that contains a modified form of ATP, which cannot be split into ADP and Pi. At what step will myofibril function be arrested by using this compound instead of unmodified ATP?
A. The myosin heads will remain attached to the actin filaments after the power stroke. B. Myosin heads will bind to the actin filaments, but the power stroke will not occur and actin filaments will not slide over the myosin filaments. C. Myosin heads will be unable to bind to the actin filaments. D. Myosin molecules will be unable to assemble into thick filaments. E. There will be no block in the cycle, since ATP hydrolysis is not required for this process.
Cyclic AMP is a type of nucleotide
__________________Indicate whether the statement is true or false.