Answer: The correct answer is-
an agent that causes a mutation in DNA.
Mutagen is an agent or a substance that causes permanent change in the genetic material of living organisms ( DNA, deoxyribonucleic acid). This process is called mutation.
A mutagen can be a chemical, physical or biological agent that causes mutation in the DNA.
Example- Physical agents such as -
- Ionizing radiations like alpha particles, gamma rays, X-rays that brings break in the DNA and cause other damages.
- Ultraviolet radiations that creates pyrimidine dimers ( T=T) and causes replication errors if damage is not repaired.
Answer:
they are found in all amino acids
During telophase of Mitosis nuclear membranes of two separated nuclei are formed around each set of chromosomes.
<u>Explanation</u>:
Mitosis is the process of cell division part of the cell cycle. Mitosis is classified into four phases which are prophase, metaphase, anaphase and telophase. In prophase the nucleolus disappears, chromosomes start to contents and the mitotic spindle starts to appear and bind to the kinetochore of centromere of the chromosomes. In metaphase nuclear envelope breaks down and the chromosomes becomes fully condensed and organized on the metaphase plate in the middle of the nucleus, during anaphase chromosomes are pulled back to their centromeres with the help of spindle fibers and during telophase the chromosomes starts to decondense, the nucleous reappears and nuclear membrane reforms and spindle starts to disappear.
