What type of mutation alters the base, but not the amino acid being coded for?
Point
Nonsense
Back
Silent
Missense
The Correct Answer is D
A. Point: A point mutation involves a change in a single nucleotide base in the DNA sequence. While it describes the location of the change, it does not specify the effect on the amino acid. A point mutation can result in silent, missense, or nonsense outcomes depending on the codon affected.
B. Nonsense: A nonsense mutation changes a codon to a stop codon, prematurely terminating protein synthesis. This produces a truncated and usually nonfunctional protein, which is distinct from a mutation that does not alter the amino acid sequence.
C. Back: A back mutation (or reverse mutation) occurs when a mutated gene reverts to its original sequence. While this restores the original function, it is not the type of mutation that leaves the amino acid unchanged on the first occurrence.
D. Silent: A silent mutation changes a nucleotide base in the DNA but does not alter the amino acid sequence due to the redundancy of the genetic code. For example, both GAA and GAG code for glutamic acid, so a change from A to G at the third base is silent. This mutation does not affect protein function but may still influence gene expression in rare cases.
E. Missense: A missense mutation changes a single nucleotide and results in a different amino acid being incorporated into the protein. This can alter protein function and structure, unlike a silent mutation which leaves the amino acid unchanged.
Nursing Test Bank
Naxlex Comprehensive Predictor Exams
Related Questions
Correct Answer is B
Explanation
A. Yeast: Yeast are single-celled fungi with relatively low resistance to physical and chemical agents. They are susceptible to heat, disinfectants, and antiseptics because they lack specialized protective structures like endospores, making them easier to control compared to more resistant microbial forms.
B. Bacterial endospores: Bacterial endospores are highly resistant, dormant structures formed by certain bacteria such as Bacillus and Clostridium species. They have a tough protective coat, low water content, and metabolic inactivity, which make them impervious to heat, radiation, desiccation, and many chemical disinfectants. Endospores can survive extreme environmental conditions for extended periods, making them the most resistant microbial form.
C. Fungal spores: Fungal spores provide some resistance to environmental stress and disinfectants, but they are significantly less resistant than bacterial endospores. Most fungal spores can be inactivated by standard sterilization techniques such as autoclaving.
D. Protozoan cysts: Protozoan cysts are protective forms that allow protozoa to survive harsh environments, including changes in pH and desiccation. While they are moderately resistant, they are not as impervious to sterilization methods as bacterial endospores.
E. Naked viruses: Naked (non-enveloped) viruses are more resistant than enveloped viruses to detergents and some disinfectants due to the absence of a lipid envelope. However, they are still more susceptible to heat, radiation, and chemical agents than bacterial endospores.
Correct Answer is B
Explanation
A. Guanine: Guanine pairs with cytosine in both DNA and RNA through three hydrogen bonds. It does not pair with uracil, as the chemical structure of uracil does not allow stable hydrogen bonding with guanine.
B. Adenine: In RNA, uracil replaces thymine and forms two hydrogen bonds with adenine. This base-pairing maintains the complementary structure needed for RNA transcription and folding, ensuring accurate coding during protein synthesis.
C. Thymine: Thymine is found only in DNA and pairs with adenine. In RNA, uracil substitutes for thymine, so thymine does not pair with uracil.
D. Cytosine: Cytosine pairs with guanine via three hydrogen bonds in both DNA and RNA. Cytosine does not pair with uracil because the hydrogen bonding does not match the structural requirements.
Whether you are a student looking to ace your exams or a practicing nurse seeking to enhance your expertise , our nursing education contents will empower you with the confidence and competence to make a difference in the lives of patients and become a respected leader in the healthcare field.
Visit Naxlex, invest in your future and unlock endless possibilities with our unparalleled nursing education contents today
Report Wrong Answer on the Current Question
Do you disagree with the answer? If yes, what is your expected answer? Explain.
Kindly be descriptive with the issue you are facing.