Answer:
The DNA in prokaryotes is contained in a central area of the cell called the nucleoid, which is not surrounded by a nuclear membrane. Many prokaryotes also carry small, circular DNA molecules called plasmids, which are distinct from the chromosomal DNA and can provide genetic advantages in specific environments.
Explanation:
Answer:
I wasn't quite sure what virus you were referring to in your question, but here's a general answer: Viruses use their host cells' machinery to replicate themselves.
If they are a specific type of virus known as a retrovirus, they have the ability to use the host cells' enzymes to change the RNA contained within the virus into DNA (via some type of replication I suppose).
In other cases, if they contain DNA instead of RNA (that is, the virus), they can use the host cell's machinery to create RNA via enzymes involved in transcription and/or they can incorporate that DNA into the host cell's DNA. This is part of a type of viral replication cycle known as the lysogenic cycle.
In another type of viral replication cycle known as the lytic cycle, the virus simply has itself and its genome duplicated until the host cell bursts, releasing the viral material. Here, again, the virus uses the host cell's machinery to replicate itself.
Explanation:
1) The enzyme helicase catalyses the unwinding of the two DNA strands by disrupting the hydrogen bonds between complementary base pairs.
2) Single-stranded binding proteins attach to the DNA strands to stabilise them and prevent them from joining back together.
3) The enzyme primase catalyses the addition of a short primer consisting of RNA nulceotides to the DNA strand. This serves as an 'anchor' DNA polymerase to initiate replication.
4) The enzyme DNA polymerase synthesizes a new DNA strand by incorporating DNA nucleotides complementary to the existing strand. DNA polymerase activity only occurs in the 5' ---> 3' direction.
5) The enzyme ligase catalyses the formation of hydrogen bonds between the two new pairs of DNA strands, and seals any breakages in the sugar-phosphate backbone.
Answer:
Gene therapy replaces a faulty gene or adds a new gene in an attempt to cure disease or improve your body's ability to fight disease. Gene therapy holds promise for treating a wide range of diseases, such as cancer, cystic fibrosis, heart disease, diabetes, hemophilia and AIDS.
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