1.
DNA transformation involves the transfer of naked DNA into a recipient cell.
Correct Answer
A. True
Explanation
DNA transformation is a process in which foreign DNA is taken up and integrated into the genome of a recipient cell. This transfer of DNA can occur in both prokaryotic and eukaryotic cells. In the case of bacterial transformation, naked DNA (DNA that is not enclosed within a membrane or a viral capsid) is directly taken up by the recipient cell. This process allows for the introduction of new genetic material into the cell, leading to altered traits or functions. Therefore, the statement that DNA transformation involves the transfer of naked DNA into a recipient cell is true.
2.
In the first step double-stranded donor DNA binds to specific receptors on the surface of a competent cell.
Correct Answer
A. True
Explanation
The statement is true because in the process of bacterial transformation, double-stranded donor DNA does indeed bind to specific receptors on the surface of a competent cell. This binding is necessary for the subsequent uptake and incorporation of the donor DNA into the recipient cell's genome. The receptors on the cell surface facilitate the recognition and binding of the donor DNA, allowing for the transfer of genetic material between cells.
3.
The purpose of surface proteins on bacterial species is to recognize and transport DNA from closely related bacterial species into the cell.
Correct Answer
A. True
Explanation
Surface proteins on bacterial species serve as receptors that recognize and facilitate the uptake of DNA from closely related bacterial species. This process is known as horizontal gene transfer, where genetic material is transferred between different bacteria. By acquiring DNA from other bacteria, the recipient bacterium can gain new genes and potentially acquire beneficial traits, such as antibiotic resistance or the ability to metabolize new substances. Therefore, the statement that surface proteins on bacterial species are responsible for recognizing and transporting DNA from closely related bacterial species into the cell is true.
4.
In Bacterial transformation, the bacteria take up and express foreign DNA usually in the form of a________
Correct Answer
A. Plasmid
Explanation
In bacterial transformation, the bacteria take up and express foreign DNA usually in the form of a plasmid. Plasmids are small, circular DNA molecules that can replicate independently within the bacterial cell. They often carry genes that provide advantages to the bacteria, such as antibiotic resistance. When foreign DNA is introduced into the bacteria through a plasmid, the bacteria can incorporate and express this DNA, allowing them to produce new proteins or exhibit new traits. Therefore, plasmids play a crucial role in bacterial transformation.
5.
Does amplification occur after transformation?
Correct Answer
A. True
Explanation
Amplification refers to the increase in the number or amount of something. In the context of transformation, amplification can occur when the DNA being transformed is replicated or multiplied. This can result in an increased amount of the transformed DNA, leading to a higher chance of successful transformation. Therefore, it is correct to say that amplification can occur after transformation.
6.
In order to persist and be stably maintained in the cell, a plasmid DNA molecule must contain what?
Correct Answer
D. Origin of replication
Explanation
A plasmid DNA molecule must contain an origin of replication in order to persist and be stably maintained in the cell. The origin of replication is a specific sequence of DNA that serves as a starting point for DNA replication. It allows the plasmid to be replicated and passed on to daughter cells during cell division. Without an origin of replication, the plasmid would not be able to replicate and would eventually be lost from the cell population.
7.
Markers are used for identifying E.coli cells.
Correct Answer
A. True
Explanation
Markers are used for identifying E.coli cells. This statement is true because markers, such as fluorescent dyes or specific antibodies, can be used to label or tag E.coli cells, allowing researchers to easily identify and distinguish them from other types of cells. These markers can bind to specific molecules or structures present on the surface of E.coli cells, enabling their detection and identification in various research or diagnostic applications.
8.
At what temperature should E. coli be incubated?
Correct Answer
D. 37 C
Explanation
E. coli should be incubated at 37°C because it is the optimal temperature for its growth and reproduction. This temperature allows the bacteria to metabolize nutrients efficiently and reproduce at a rapid rate. Incubating E. coli at lower temperatures, such as 10°C or 15°C, would slow down its growth and reproduction, while incubating it at higher temperatures, such as 20°C, may cause the bacteria to become stressed or even die. Therefore, 37°C is the most suitable temperature for incubating E. coli.
9.
The purpose of calcium chloride is to allow the plasmid to pass through the bacterial cell wall.
Correct Answer
A. True
Explanation
Calcium chloride is commonly used in molecular biology experiments to enhance the efficiency of bacterial transformation. It works by neutralizing the negative charges on the bacterial cell wall, making it more permeable to foreign DNA such as plasmids. This allows the plasmid to enter the bacterial cell, increasing the chances of successful transformation. Therefore, the statement that the purpose of calcium chloride is to allow the plasmid to pass through the bacterial cell wall is true.
10.
Electroporation is a mechanical method used to introduce polar molecules into a host cell through the cell membrane.
Correct Answer
A. True
Explanation
Electroporation is a technique used to introduce polar molecules into a host cell by applying an electric field to the cell membrane. This electric field temporarily disrupts the cell membrane, creating pores that allow the polar molecules to enter the cell. Therefore, the statement "Electroporation is a mechanical method used to introduce polar molecules into a host cell through the cell membrane" is true.