Enter a player name to begin or load your saved progress.
Plasmids are extrachromosomal DNA molecules commonly found in bacteria and archaea that can replicate independently.
Answer: True
Explanation: Plasmids are defined as extrachromosomal DNA molecules that exist outside the cell's main chromosome and possess the capability for autonomous replication. They are prevalent in bacteria and archaea.
The primary role of chromosomal DNA is to contain genes essential for a cell's survival under normal conditions.
Answer: True
Explanation: Chromosomal DNA serves as the primary repository for genes indispensable for a cell's fundamental survival and operation under standard environmental conditions.
Plasmids, like viruses, are generally classified as living organisms.
Answer: False
Explanation: Plasmids are not generally classified as living organisms; rather, they are genetic elements that are dependent on host cells for their replication and functional expression, similar to viruses.
Unlike viruses, plasmids are enclosed within a protective protein coat called a capsid.
Answer: False
Explanation: Plasmids, in contrast to viruses, are not enclosed by a protective protein coat known as a capsid; they are composed of 'naked' DNA.
Naturally occurring plasmids can range in size from very small mini-plasmids to very large megaplasmids.
Answer: True
Explanation: Naturally occurring plasmids exhibit considerable size variation, encompassing entities from diminutive mini-plasmids to extensive megaplasmids.
What is the fundamental definition of a plasmid?
Answer: A small, extrachromosomal DNA molecule that can replicate independently of the cell's chromosome.
In which types of organisms are plasmids most commonly found?
Answer: Primarily in bacteria and archaea, but also in eukaryotes.
What kind of genetic information do plasmids typically carry that is not usually found in chromosomal DNA?
Answer: Additional genes providing special advantages like antibiotic resistance or virulence.
How does the role of plasmids differ from that of chromosomal DNA within a cell?
Answer: Chromosomal DNA contains essential genes for normal survival, while plasmids contain genes for special traits or advantages in specific circumstances.
Are plasmids generally classified as living organisms?
Answer: No, they are genetic elements that rely on host cells for replication and function.
What is the typical size range of naturally occurring plasmids?
Answer: From 1 kilobase pair (kbp) to several megabase pairs (Mbp).
Plasmids are considered replicons, meaning they are units of DNA capable of replicating autonomously.
Answer: True
Explanation: Plasmids are classified as replicons, signifying that they are discrete units of DNA possessing the inherent capacity for autonomous replication within a suitable cellular environment.
The plasmid copy number is influenced by how its replication initiation is regulated and its molecular size.
Answer: True
Explanation: The number of plasmid copies maintained within a cell, known as the copy number, is determined by factors such as the regulation of its replication initiation and its overall molecular size.
Partition systems are mechanisms found in low-copy-number plasmids that ensure distribution to daughter cells.
Answer: True
Explanation: Partition systems are specialized mechanisms present in low-copy-number plasmids, designed to guarantee their equitable distribution into daughter cells during cell division.
What does the term 'replicon' refer to in the context of plasmids?
Answer: A unit of DNA capable of replicating autonomously within a suitable host cell.
What are the components of a typical bacterial replicon?
Answer: A gene for a plasmid-specific replication initiation protein (Rep), iterons, DnaA boxes, and an adjacent AT-rich region.
What is the function of the 'origin of replication' (ori) on a plasmid?
Answer: To serve as the specific stretch of DNA essential for its independent replication within a cell.
Conjugation is the primary method by which plasmids are transmitted between bacteria.
Answer: True
Explanation: Conjugation is recognized as the principal mechanism through which plasmids are transferred between bacterial cells, representing a key form of horizontal gene transfer.
Conjugative plasmids contain transfer genes to promote conjugation, while non-conjugative plasmids cannot initiate it alone.
Answer: True
Explanation: Conjugative plasmids are characterized by the presence of transfer genes that facilitate conjugation, whereas non-conjugative plasmids lack these genes and are therefore unable to initiate conjugation independently.
Mobilizable plasmids can transfer at high frequency independently of other plasmids.
Answer: False
Explanation: Mobilizable plasmids require the assistance of conjugative plasmids to transfer at high frequency; they cannot perform this process independently.
Plasmids are assigned to incompatibility groups based on whether they can coexist in the same bacterial cell.
Answer: True
Explanation: Incompatibility groups are designations for plasmids based on their inability to coexist within the same bacterial cell, typically due to shared replication or partitioning machinery.
Plasmids are primarily transmitted between bacteria through a process called transformation.
Answer: False
Explanation: The primary mechanism for plasmid transmission between bacteria is conjugation, not transformation, which is typically employed in laboratory settings for DNA introduction.
Mobilizable plasmids can transfer at high frequency independently of other plasmids.
Answer: False
Explanation: Mobilizable plasmids require the assistance of conjugative plasmids to transfer at high frequency; they cannot perform this process independently.
Plasmids are assigned to incompatibility groups based on whether they can coexist in the same bacterial cell.
Answer: True
Explanation: Incompatibility groups are designations for plasmids based on their inability to coexist within the same bacterial cell, typically due to shared replication or partitioning machinery.
Plasmids are primarily transmitted between bacteria through a process called transformation.
Answer: False
Explanation: The primary mechanism for plasmid transmission between bacteria is conjugation, not transformation, which is typically employed in laboratory settings for DNA introduction.
How are plasmids primarily transmitted from one bacterium to another?
Answer: Via horizontal gene transfer through conjugation.
What are the two main categories of plasmids based on their ability to transfer between cells?
Answer: Conjugative and Non-conjugative plasmids.
Degradative plasmids provide bacteria with the enzymes to digest unusual substances like toluene.
Answer: True
Explanation: Degradative plasmids confer upon bacteria the enzymatic machinery necessary for the catabolism of uncommon substrates, such as toluene.
Virulence plasmids turn a bacterium into a pathogen by providing genes that help it colonize a host and overcome defenses.
Answer: True
Explanation: Virulence plasmids contribute to pathogenicity by encoding genes that enhance a bacterium's ability to colonize a host and evade host defense mechanisms.
Cryptic plasmids are known to always provide a clear survival advantage to their host bacteria.
Answer: False
Explanation: Cryptic plasmids do not consistently confer a clear survival advantage to their host bacteria, although recent research suggests potential roles in phenomena like heteroresistance.
Chromids are genetic elements that exist at the boundary between a chromosome and a plasmid.
Answer: True
Explanation: Chromids are defined as genetic elements situated at the interface between chromosomal and plasmid DNA in certain bacteria.
Degradative plasmids provide bacteria with the enzymes to digest unusual substances like toluene.
Answer: True
Explanation: Degradative plasmids equip bacteria with the necessary enzymes to metabolize unusual compounds, such as toluene.
Virulence plasmids turn a bacterium into a pathogen by providing genes that help it colonize a host and overcome defenses.
Answer: True
Explanation: Virulence plasmids contribute to pathogenicity by encoding genes that enhance a bacterium's ability to colonize a host and evade host defense mechanisms.
Cryptic plasmids are known to always provide a clear survival advantage to their host bacteria.
Answer: False
Explanation: Cryptic plasmids do not consistently confer a clear survival advantage to their host bacteria, although recent research suggests potential roles in phenomena like heteroresistance.
Chromids are genetic elements that exist at the boundary between a chromosome and a plasmid.
Answer: True
Explanation: Chromids are defined as genetic elements situated at the interface between chromosomal and plasmid DNA in certain bacteria.
Which of the following is NOT one of the five main functional classifications of plasmids?
Answer: Replicative plasmids
What do Fertility (F) plasmids contain that enables them to undergo conjugation and express sex pili?
Answer: Specific transfer genes (*tra* genes)
What is the significance of Resistance (R) plasmids?
Answer: They contain genes conferring resistance to antibiotics, contributing to multidrug resistance.
What do Col plasmids encode?
Answer: Proteins capable of killing other bacteria (bacteriocins).
What is the purpose of Degradative plasmids?
Answer: To enable bacteria to digest unusual substances.
How do Virulence plasmids contribute to a bacterium's pathogenicity?
Answer: By providing genes that help the bacterium colonize a host and overcome its defenses.
Artificial plasmids are widely used as vectors in molecular cloning to drive the replication of recombinant DNA sequences.
Answer: True
Explanation: Artificial plasmids are instrumental in molecular cloning, functioning as vectors to facilitate the replication of recombinant DNA sequences within host cells.
Plasmids are introduced into host cells in a laboratory setting through a process known as transformation.
Answer: True
Explanation: In laboratory environments, the introduction of plasmids into host cells is commonly achieved via a technique termed transformation.
pMLST is a method used to cluster or type plasmids based on their sequence content.
Answer: True
Explanation: pMLST (plasmid multi-locus sequence typing) is a technique utilized for classifying and typing plasmids by analyzing their sequence content.
A multiple cloning site (polylinker) on a cloning vector plasmid contains various restriction sites for inserting DNA fragments.
Answer: True
Explanation: A multiple cloning site, or polylinker, on a plasmid cloning vector is characterized by the presence of multiple restriction sites, which are crucial for inserting DNA fragments.
The antibiotic resistance gene on a cloning vector plasmid acts as a selectable marker.
Answer: True
Explanation: The antibiotic resistance gene present on a cloning vector plasmid serves as a selectable marker, enabling the identification of transformed cells.
A suicide vector is designed to replicate efficiently in the host cell to ensure stable inheritance.
Answer: False
Explanation: A suicide vector is designed not to replicate efficiently in the host cell; its purpose is to integrate into the host chromosome or be lost, rather than to ensure stable inheritance through replication.
Insulin is a prominent example of a protein produced using plasmids in bacteria.
Answer: True
Explanation: The production of insulin via recombinant DNA technology in bacteria, utilizing plasmids, is a prominent example of protein synthesis.
The 2 micron plasmid is found in the common baker's yeast *Saccharomyces cerevisiae*.
Answer: True
Explanation: The 2 micron plasmid is a notable plasmid found in the widely used baker's yeast, *Saccharomyces cerevisiae*.
pMLST is a method used to cluster or type plasmids based on their sequence content.
Answer: True
Explanation: pMLST (plasmid multi-locus sequence typing) is a technique utilized for classifying and typing plasmids by analyzing their sequence content.
A multiple cloning site (polylinker) on a cloning vector plasmid contains various restriction sites for inserting DNA fragments.
Answer: True
Explanation: A multiple cloning site, or polylinker, on a plasmid cloning vector is characterized by the presence of multiple restriction sites, which are crucial for inserting DNA fragments.
The antibiotic resistance gene on a cloning vector plasmid acts as a selectable marker.
Answer: True
Explanation: The antibiotic resistance gene present on a cloning vector plasmid serves as a selectable marker, enabling the identification of transformed cells.
A suicide vector is designed to replicate efficiently in the host cell to ensure stable inheritance.
Answer: False
Explanation: A suicide vector is designed not to replicate efficiently in the host cell; its purpose is to integrate into the host chromosome or be lost, rather than to ensure stable inheritance through replication.
Insulin is a prominent example of a protein produced using plasmids in bacteria.
Answer: True
Explanation: The production of insulin via recombinant DNA technology in bacteria, utilizing plasmids, is a prominent example of protein synthesis.
The 2 micron plasmid is found in the common baker's yeast *Saccharomyces cerevisiae*.
Answer: True
Explanation: The 2 micron plasmid is a notable plasmid found in the widely used baker's yeast, *Saccharomyces cerevisiae*.
What is the primary use of artificial plasmids in molecular biology?
Answer: To act as vectors for replicating recombinant DNA sequences.
What is the process called by which plasmids are introduced into host cells in a laboratory setting?
Answer: Transformation
What is pMLST used for in plasmid research?
Answer: To cluster or type plasmids based on their sequence content, particularly replication machinery genes.
What is the purpose of the antibiotic resistance gene on a plasmid used as a cloning vector?
Answer: To provide a selectable marker, allowing survival of transformed cells on antibiotic-containing media.
What is a 'suicide vector' in the context of plasmids?
Answer: A plasmid that cannot replicate in the host cell and must integrate or be lost.
How are plasmids utilized for protein production?
Answer: By inserting the gene of interest into the plasmid, introducing it into bacteria, and then inducing the bacteria to produce the protein.
What is a prominent example of a protein produced using plasmids in bacteria?
Answer: Insulin
Which of the following is a key feature typically found in a plasmid used as a cloning vector?
Answer: A gene conferring antibiotic resistance.
The term 'plasmid' was coined by Joshua Lederberg in 1952.
Answer: True
Explanation: The term 'plasmid' was first introduced and defined by Joshua Lederberg in the year 1952.
The definition of a plasmid has always exclusively referred to genetic elements outside the chromosome that replicate autonomously.
Answer: False
Explanation: The definition of a plasmid has evolved; initially, it encompassed a broader range of genetic elements, but it was later refined to exclusively refer to extrachromosomal genetic elements that replicate autonomously.
Who coined the term 'plasmid,' and what was its original definition?
Answer: Joshua Lederberg in 1952, defining it as 'any extrachromosomal hereditary determinant.'
What was Joshua Lederberg's original definition of a plasmid in 1952?
Answer: Any extrachromosomal hereditary determinant.