The correct answer is: A. A change in a cell's genetic material.
Mutations occur in DNA as a result of mistakes during the DNA replication (when repair mechanisms don’t fix it) or as the result of environmental factors (e.g. UV light). Mutations can have positive impact, by increasing the genetic variation or can have negative effect, causing the diseases or cancer.
Antarctic soil differs from other soil because it is formed from volcanic rocks
Answer:
e. None of these
Explanation:
The immune deficiency viruses (HIV) are retroviruses that use a reverse transcriptase (RT) enzyme to produce a single-stranded DNA (ssDNA) from an RNA template. The reverse transcription allows retroviruses to replicate their genetic material, which is integrated into the host's genome as a double-stranded linear DNA molecule in a similar way to the mechanism of insertion used by endogenous retrotransposons. The synthesis of DNA is started by cellular tRNAs (tRNA3Lys) that are packaged into the virion. After reverse transcription, the HIV DNA enters the nucleus of CD4 immune cells (also known as CD4+ T cells), and then it integrates into the genome to coopt the host's cell machinery for its own replication.
It has a lot of advantages as well as disadvantages; but they prevent or suppress the entry of pathogens; colonies produced by some organisms of normal flora have a harmful effect on the pathogens; endotoxins liberated by normal flora may help the defense mechanism of the body. (Make me the brainless please)
Is spread from one person to another through a variety of ways that include: contact with blood and bodily fluids; breathing in an airborne virus; or by being bitten by an insect.
