Why is it necessary to have a new vaccine for influenza every year?
Group of answer choices
Influenza is caused by a DNA virus, which tends to mutate more quickly than RNA viruses.
Influenza is caused by an RNA virus, which tends to mutate more quickly than DNA viruses.
The influenza virus is not enveloped; therefore, it is more susceptible to mutation than enveloped viruses.
The influenza virus does not have a capsid; therefore, it is more susceptible to mutation than other viruses.
Influenza is caused by a retrovirus; therefore, it is more error-prone.
Answer
Influenza is caused by an RNA virus, which tends to mutate more quickly than DNA viruses.
Explanation
There are two general types of viruses in regards to their genome type: the DNA viruses and RNA viruses. DNA viruses have a high level of proofreading their genome which is why it became so easy to contain smallpox virus. On the other hand, RNA viruses replicate without proofreading as in DNA viruses, which is why the viruses like influenza and HIV have high genetic mutation because of the high amount of errors in their genome. To eradicate these viruses, vaccines have to be formed every year to cover the changed genome.
Question:
why stacked bases in DNA/RNA absorb small amount of UV light than do unstacked bases
Answer
This concept of denatured or unstacked DNA absorbing more UV than stacked DNA is called the hyperchromic shift. Usually, all bases in DNA absorb UV, but stacked DNA absorbs less UV because of the interactions that exist between the bases. In stacked DNA, the hydrogen bonds between the bases limits the resonance of the aromatic ring of purines and pyrimidines so the absorbance of the sample is limited as well.
Explanation
In unstacked DNA, the hydrogen bonds are disrupted, the two single strands are separated reducing the base-base interaction. This causes higher UV absorbance because many bases are in free form and there is no hdyrogen bonds between complimentary bases. A single strand will absorb b 37% more UV than a double stranded DNA.
Reference
- Alexander, R.R. and Griffiths, J.M. (1993) Basic Biochemical Methods, 2nd Edition. J.M. Wiley and Sons, New York.
Question:
Order: meperidine (Demerol) 75 mg p.o. syrup every 3 hours prn pain. Available: meperidine 50mg/3mL. How many mL will you give per dose?
Answer
One dose of the drug will be 4.5 mL
Explanation
Order: meperidine (Demerol) 75 mg p.o. syrup every 3 hours prn pain.
Available: meperidine 50mg/3mL. How many mL will you give per dose?
Solution
Start by calculating amount in mL of the drug in 1 mg
50 mg = 3 mL
1 mg = ?
1 mg = 1 * 3/50 = 0.06 mL
1 mg of the drug has 0.06 mL
One dose = 75 mg
if 1 mg = 0.06 mL
75 mg = 75 * 0.06/1 = 4.5 mL
One dose of the drug will be 4.5 mL
Question:
When the energy needed for bond making is _____ the energy needed for bond breaking, the reaction is exothermic:
a. equal to
b. None of these
c. more than
d. less than
Answer
b. None of these
Explanation
No answer in the above options because whether a reaction is endothermic or exothermic depends on the difference between energy released by bond breaking and energy needed for bond formation.
The process of breaking a bond uses energy hence an endothermic process, while the process of making a bond is exothermic. Whether a reaction is characterized as endothermic or exothermic depends with the difference between the energy needed to break a bond and the energy released when new bond is formed. A reaction is exothermic if the energy released or formed is greater than the energy required to form a bond.
The correct statement should read as follows: When the energy released in bond making is greater than the energy needed for bond breaking, then the reaction is exothermic.
