Alzheimer's disease correct answers a chronic neurodegenerative (loss of structure, function, and
potentially death of neurons) disease with a prominent symptom of memory loss. Characterized
by excessive apoptosis
Parkinson's disease correct answers a neurodegenerative (loss of structure, function, and
potentially death of neurons) disease with symptoms of motor control loss. Characterized by
excessive apoptosis
Turner syndrome correct answers an aneuploidy (specifically a monosomy) that is the result of a
missing X chromosome due to nondisjunction in gamete formation during meiosis. Rather than
having the expected sex genotype of XX, a female with Turner Syndrome would be XO,
indicating the absence of an X chromosome
Huntington's disease correct answers a neurodegenerative (loss of structure, function, and
potentially death of neurons) disease with symptoms of declining mental (and eventually
physical) ability over time. Characterized by excessive apoptosis
Apoptosis correct answers cells do not rupture or cause an inflammatory response. They continue
to shrink, eventually resulting in nuclear collapse and the formation of apoptotic bodies that are
eventually lysed. Apoptosis is an essential part of normal development.
Q: A scientist wants to detach a peripheral membrane protein from the exterior of a cell
membrane. Which is the best method to do so?
A. Change the salt concentrations.
B. Perform a light centrifuge.
C. Add a detergent.
D. Change the temperature of the solution.
E. Run a small current through the solution. correct answers Answer: A
,A. Change the salt concentrations.
Peripheral membrane proteins are held in place by hydrogen bonding and electrostatic
interactions. To detach such a protein from a cell membrane's exterior, one would need to disrupt
these forces. There are two methods that will accomplish this task: changing the salt
concentration, or changing the pH (altering the H+ concentration). The answer choice is correct.
B. Perform a light centrifuge.
Performing a light centrifuge would most likely disrupt the cell membrane and cause it to break
apart, releasing its contents and fragmenting the membrane itself, with no specificity for
detaching membrane proteins; therefore the answer choice is incorrect. Centrifuging is often
used to break apart cells to separate their organelles on the basis of size and shape, as seen in the
technique of differential centrifugation.
C. Add a detergent.
Adding a detergent would destroy the membrane, not detach peripheral membrane proteins;
therefore the answer choice is incorrect. Detergents are useful when one needs to expose integral
proteins embedded in the membrane (as integral membrane proteins are hydrophobic).
D. Change the temperature of the solution.
Changing the temperature of a solution could have several consequences, but efficiently
detaching peripheral membrane proteins would not be one of them. A raise in temperature could
potentially denature the peripheral membrane protein, or even disrupt the cell membrane itself.
Sufficiently lowering the temperature could similarly result in disruption of the membrane.
Neither of these effects is ideal for detaching peripheral membrane proteins; therefore the answer
choice is incorrect.
E. Run a small current through the solution.
Running a small current through the solution - a technique known as electroporation - is used to
create temporar
, The Miller-Urey experiment correct answers The Miller-Urey experiment used ammonia,
methane, water and hydrogen sealed in a sterile arrangement of tubes and flasks with connecting
loops. One flask was half-filled with liquid water and the other with 2 electrodes (to simulate
lighting in early earth). The flask with water was heated to simulate the temperature of early
Earth, and sparks were fired from the electrodes to simulate lightning. After 2 weeks, they
observed several organic compounds, amino acids (11 out of 20) and their base starting
materials. However, no complete nucleic acids were observed.
All of the following were observed by Miller-Urey in their classic experiment to check the
hypothesis of the "chemical origins of life" EXCEPT for one. Which one is the EXCEPTION?
A. Methane
B. Amino acids
C. Ammonia
D. Organic compounds
E. Nucleic acids correct answers Answer: E
A. Methane
Methane (CH4) was one of the starting substances used in the Miller-Urey experiment; therefore
the answer choice is incorrect.
B. Amino acids
Amino acids were one of the products observed in the Miller-Urey experiment, as a result of the
starting compounds (H2O, H2, CH4, and NH3) interacting with sparks designed to imitate
lightning in the early atmosphere; therefore the answer choice is incorrect.
C. Ammonia
Ammonia (NH3) was one of the starting substances used in the Miller-Urey experiment;
therefore the answer choice is incorrect.
D. Organic compounds