Question

What can be the result of a genetic (DNA or plasmid) mutation in a prokaryote?

Select one or more:

a. Endospore formation

b. Antibiotic resistance

c. Meiosis beginning

d. Exponential decay in growth

e. All of the above

Which statement does not describe the structure of a virus?

Select one or more:

a. Some have a core of a nucleic acid (DNA) surrounded by a protein

b. Some have a core of a nucleic acid (RNA) surrounded by a protein

c. A capsid surrounds the nucleic acid core

d. Some have an envelope that surrounds the capsid which is rich in proteins and lipids

e. None of the above

Answer 1

What can be the result of a genetic (DNA or plasmid) mutation in a prokaryote?

Select one or more:

a. Endospore formation

b. Antibiotic resistance

c. Meiosis beginning

d. Exponential decay in growth

e. All of the above

ANSWER – Option B – Antibiotic Resistance

EXPLANATION

Antibiotics /Antimicrobial drugs, - are drugs that fight infections caused by bacteria.

Alexander Fleming discovered the first antibiotic - penicillin - in 1927 - discovered by Alexander Fleming.

The term "antibiotic" originally - refers to natural compounds produced by a fungus / some another microorganism that kills bacteria that are pathogenic in humans or animals.

Antibiotics are of 2 types – natural as well as synthetic – both kill or inhibit the growth of microbes.

So the term "antimicrobial agent" technically refers to both natural & synthetic compounds. But, many people use the word "antibiotic" to refer to both.

Antibiotics have many beneficial effects but their use has contributed to the problem of antibiotic resistance.

Antibiotic resistance

                         Defined as - the ability of bacteria or other microbes to resist the effects of an antibiotic. It happens when bacteria change in some way or another that results in the reduction or nullification of the effectiveness of drugs, chemicals, or other agents designed to cure or prevent that corresponding infections. Thus the bacteria will have the ability to survive and thus continues to multiply causing more harm to the affected ones.

Antibiotics have the ability to kill or inhibit the growth of susceptible bacteria. But what happens is sometimes one of the bacteria survives because it has the ability to neutralize or reduce the effect of the antibiotic; that one bacterium will then multiply and replaces all the bacteria that were killed off. Exposure to antibiotics therefore acts as a selective pressure, making the surviving bacteria more resistant.

                Another problem is that, the bacteria that were at one time susceptible to that particular antibiotic will acquire more resistance by mutation of their genetic material or by the selective acquisition of pieces of DNA that codes for the resistance properties from other bacteria. The DNA that codes for resistance can be grouped in a single easily transferable package and thus acquired by that bacteria for higher resistance. This implies that bacteria will become more resistant to many antimicrobial agents just because of the transfer of one piece of DNA.

Which statement does not describe the structure of a virus?

Select one or more:

a. Some have a core of a nucleic acid (DNA) surrounded by a protein

b. Some have a core of a nucleic acid (RNA) surrounded by a protein

c. A capsid surrounds the nucleic acid core

d. Some have an envelope that surrounds the capsid which is rich in proteins and lipids

e. None of the above

ANSWER - NONE OF THE ABOVE

EXPLANATION

Viruses are - Small obligate intracellular parasites.

Multiply like other organisms - but only in the presence and inside of a living cell.

They are noncellular particles made up of genetic material and proteins that have ability to invade living cells.

Vary in size from 20-400 nm.

Viral Genome – is EITHER RNA or DNA genome - surrounded by a virus-coded protein coat (Capsid)( protective function)

The DNA or RNA genome may be :single stranded or double stranded.

The nucleic acid genome and the protective protein coat is combinely called the nucleocapsid which appears in different structures like icosahedral, helical or complex symmetry.

FEATURES

Non living structures

Non-cellular

Contain a protein coat called the capsid

Presence of nucleic acid core containing DNA or RNA - not both (one or the other) .

Capable of reproducing only when inside the host cell.

ONLY Some viruses are enclosed in an protective envelope .

Some may have spikes to help attach to the host cell.