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When the enzyme has passed the end of the DNA, two identical molecules of DNA are left behind.
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The direction of DNA replication on the leading strand occurs in the?
The enzyme DNA polymerase synthesises strands in the 5 prime to 3 prime direction, and as DNA is antiparallel the replication of the leading strand occurs from the 3 prime end of the template to the 5 prime end of the template.
How are copies of DNA made?
DNA is copied by breaking the hydrogen bonds keeping it together, separating itself into two complimentary strands. Lone base pairs in the nucleus attach to the now single stranded DNA, creating two identical strands of DNA.nnnlknlk A DNA molecule is copied in a process called DNA replication. During DNA replication, the enzyme helicase separates the two strands of DNA nucleotides. The nitrogen bases of the two strands of DNA nucleotides are exposed, and the enzyme DNA polymerase causes new DNA nucleotides to pair with the original, exposed nucleotides according to the base-pairing rule. The result is two identical DNA molecules, each having a new strand of DNA nucleotides, and an original strand of DNA nucleotides. This kind of replication is called semi-conservative replication.
What is an end replication problem?
The two strands of a DNA molecule are antiparallel to one another (the backbone of one strand runs from 5'-3' while the complimentary strand runs 3'-5'). Unfortunately, DNA polymerase, the enzyme responsible for replicating DNA, can only make DNA in a 5'-3' direction (and read DNA in the 3'-5' direction). Also, it needs a "primer" to give it a place to bind and start replication. So this creates a problem when synthesizing the 3'-5' stand because your enzyme will only synthesize 5'-3'. During replication this is solved by synthesizing small pieces of DNA ahead of the replication fork on the 5'-3' mother strand. Thus we have one daughter strand which is synthesized as a continuous piece of DNA (called the leading strand) and one daughter strand which is synthesized in small, discontinuous pieces (called the lagging strand). However, at the extreme end of the DNA, we run into another problem. The leading stand can be made to the very end, but the lagging strand cannot because you need the RNA primer upstream to begin each piece of the lagging strand DNA but at the end of the DNA there is nothing for this piece to attach to. Thus, the last section of the lagging strand cannot be synthesized and after several rounds of DNA replication, the DNA molecule gets smaller and smaller. This is "the end of replication problem" and it is solved by putting a DNA cap on the ends of DNA called a telomere which does not code for any protein, thus when this information is lost it does not have severe consequences for the cell.
When circular plasmid DNA is cut open at a single site by a restriction enzyme the resulting piece is?
You should end up with a linear piece of DNA the length of the entire plasmid. I don't know if there is a specific name for it. CALLED A : a linear strand
Describe how do different fragments of DNA show up on a gel?
the chamber has a positive end and a negative end...the DNA moves through the gel toward the positive end (because DNA is negative). The smaller fragments move faster, therefore going further, and the larger pieces stay closer to the wells. what is DNA gel
What is a sticky end?
A Sticky End, referring to Biology is recombinant DNA. After DNA has been cut by a restriction enzyme it has "sticky ends" or recombinant DNA at the ends.
What is the function of primer in PCR?
it synthesizes a single RNA primer at the 5' end of the leading end.
What is main function of DNA polymerase?
The DNA polymerase enzyme synthesises the complementary DNA strand to a single stranded DNA strand (in vivo and in vitro). This often requires the presence of a 3' end for the polymerase enzyme to bind to before synthesis can begin. Taq polymerase (A DNA polymerase) is often used in PCR reactions to synthesise DNA in vitro using primers to provide a 3' end to bind to.
Why is it important to use the same restriction enzyme for both cells in recombinant DNA?
Restriction enzymes are endonucleases that digest the DNA at a sequence specific site. Hind III for example cut between two As in the sequence AAGCTT in the both strand forming a sticky end. If you use this enzyme to cut in your vector DNA, you have to use the same enzyme in the insert DNA so as they can ligate by DNA ligation. This is the important use of same restriction enzyme in cloning.
What happens when a restriction enzyme is used on DNA?
when restriction enzyme is use on DNA basically it just first losen up the DNA, usally DNA is coiled, and so the restriction enzyme jsut breka the DNA and leave a sticky end, so that it can be put back together, the cell have to be able to do that because in nature, that's the way for cell to stop protein production and the cell still need that gene
How does Transcription take place?
who? the transcription enzyme RNA polymerase, the promoter DNA and the terminator DNAwhere? in the cell nucleusInitiation The promoter, located in the DNA at the beginning of the gene becomes the binding site for the RNA polymerase. Elongation the RNA polymerase copies and peels away the copied DNA, after copied, the DNA joins back with its matching DNA strand while the newly made RNA leave the polymerase Termination the RNA polymerase reaches a special sequence of bases in the DNA template that signals the end of the gene. The polymerase enzyme detaches from the RNA molecule and the gene who? the transcription enzyme RNA polymerase, the promoter DNA and the terminator DNAwhere? in the cell nucleusInitiation The promoter, located in the DNA at the beginning of the gene becomes the binding site for the RNA polymerase. Elongation the RNA polymerase copies and peels away the copied DNA, after copied, the DNA joins back with its matching DNA strand while the newly made RNA leave the polymerase Termination the RNA polymerase reaches a special sequence of bases in the DNA template that signals the end of the gene. The polymerase enzyme detaches from the RNA molecule and the gene
What is the role of DNA ligase in the enlogation of the lagging strand during DNA replication?
it is a linking enzyme essential for DNA replication; catalyzes the covalent bonding of the 3' end of one DNA fragment to the 5' end of another DNA fragment.
The direction of DNA replication on the leading strand occurs in the?
The enzyme DNA polymerase synthesises strands in the 5 prime to 3 prime direction, and as DNA is antiparallel the replication of the leading strand occurs from the 3 prime end of the template to the 5 prime end of the template.
When does a cell make sure DNA has been copied correctly before continuing in the cell cycle?
DNA is copied (or replicated) by an enzyme called DNA polymerase. This enzyme generally operates in the 3' to 5' direction. However, this enzyme also has a 5' to 3' exonuclease activity, which enables it to remove certain wrong bases and insert correct ones. This ensure that the DNA is copied correctly
Use E co RI and MseI in AFLP analysis?
Chop DNA into pieces using you restriction enzyme(s) of choice. Add adapter to sticky end, you know the sequence of the sticky end as it corrisponds to the restriction enzyme used. Use a primer for the adaptor and amplify the DNA with PCR. Ta dah you just amplified somthing you didn't have a primer for. Run the amplified DNA on a gel and you can see changes between your samples.
What is the process by which DNA is used as a template to make more DNA?
The double strand is separated by an enzyme called helicase. A primer is placed at the 3' end of the template strand. DNA Polymerase III (another enzyme) then adds new nucleotides to the primer, in the 5'-3' direction. The primers are replaced with DNA nucleotides by DNA Polymerase I and joined together by ligase. This is how DNA is replicated.
What are the principles of restriction enzyme use in removing sections of the genome?
Restriction enzymes can act only on double strand DNA . Restriction enzyme recognizes and hydrolyzes the backbone of DNA between deoxyribose and phosphate groups at or near the restriction sites. This leaves a phosphate group on the 5` ends and a hydroxyl on the 3` end of both the strands . Thus digestion with restriction enzymes results in the fragmentation of the double stranded DNA molecule.
