Which of the following represents the complementary strand of a DNA sequence "5' AGCTAGCGT 3'"?
3' AGCTAGCGT 5'.
3' TCGATCGCA 5'.
5' UCGAUCGCA 3'.
3' TCGUTCGCU 3'.
The Correct Answer is B
The correct answer is choice B. 3’ TCGATCGCA 5’.
In DNA, the nitrogenous bases adenine (A) and thymine (T) pair together, while cytosine © and guanine (G) pair together.
Therefore, the complementary strand of the given DNA sequence “5’ AGCTAGCGT 3’” would have the nitrogenous bases T, C, G, A, T, C, G, C and A in that order.
Additionally, the 5’ to 3’ direction of the complementary strand is opposite to that of the given strand.
Choice A. 3’ AGCTAGCGT 5’ is not correct because it is not complementary to the given strand.
Choice C. 5’ UCGAUCGCA 3’ is not correct because it contains uracil (U), which is a nitrogenous base found in RNA, not DNA.
Choice D. 3’ TCGUTCGCU 3’ is not correct because it also contains uracil (U), which is a nitrogenous base found in RNA, not DNA.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is A
Explanation
The threshold potential is the critical level to which a membrane potential must be depolarized to initiate an action potential.
Most often, the threshold potential is a membrane potential value between –50 and –55 mV.
The membrane potential of a neuron is determined by the distribution of ions across the cell membrane.
At rest, the inside of a neuron is more negative than the outside due to the presence of negatively charged proteins and other molecules.
The movement of ions across the cell membrane can change the membrane potential.
For example, when sodium ions enter the cell, they make the inside of the cell more positive (less negative), causing depolarization.
Choice B is incorrect because -80 mV is below the typical threshold value for mammalian neurons.
Choice C is incorrect because +35 mV is above the typical threshold value for mammalian neurons.
Choice D is incorrect because 0 mV is above the typical threshold value for mammalian neurons.
Correct Answer is A
Explanation
Melanin is a pigment produced by cells called melanocytes in the skin.
It protects the skin from ultraviolet (UV) radiation by absorbing and dissipating over 99.9% of absorbed UV radiation.
This helps to prevent DNA damage and other adverse effects of UV radiation on the skin.
Choice B. Perspiration is not correct because it is a fluid produced by sweat glands in the skin that helps to regulate body temperature, but it does not protect the skin from UV radiation.
Choice C. Sebum is not correct because it is an oily substance produced by sebaceous glands in the skin that helps to lubricate and protect the skin, but it does not protect the skin from UV radiation.
Choice D. Keratin is not correct because it is a fibrous protein that provides strength and durability to the skin, hair and nails, but it does not protect the skin from UV radiation.
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