A plasmid is __________ .


a. a molecule of RNA found in bacterial cells
b. distinguished from a chromosome by being circular
c. a structure in bacterial cells formed from plasma membrane
d. extrachromosomal DNA

Verified step by step guidance

1. Understand the definition of a plasmid in the context of microbiology.
2. Recall that plasmids are small, circular DNA molecules found in bacterial cells.
3. Differentiate plasmids from chromosomes, noting that plasmids are extrachromosomal.
4. Consider the options provided and identify which one correctly describes a plasmid.
5. Recognize that plasmids are not formed from the plasma membrane, nor are they RNA molecules.

Key Concepts

Plasmid Structure

A plasmid is a small, circular piece of DNA that exists independently of chromosomal DNA in bacterial cells. Unlike chromosomes, which are linear and essential for the organism's survival, plasmids can carry additional genes that may confer advantageous traits, such as antibiotic resistance.

Extrachromosomal DNA

Extrachromosomal DNA refers to genetic material that is not part of the chromosomal DNA. Plasmids are a prime example of extrachromosomal DNA, as they replicate independently within the cell and can be transferred between bacteria, facilitating horizontal gene transfer.

Bacterial Genetic Exchange

Bacterial genetic exchange is a process through which bacteria can share genetic material, often via plasmids. This exchange can occur through mechanisms such as conjugation, transformation, or transduction, allowing for rapid adaptation and evolution in bacterial populations.