If an organism had a DNA polymerase III that lost its ability to proofread, which of the following statements would be TRUE?
DNA could not be synthesized, and the organism would die
. DNA polymerase III would randomly add new nucleotides, and the entire sequence of new DNA would be worthless.
What would happen if DNA polymerase didn’t proofread during replication?
In nucleotide excision repair, enzymes remove incorrect bases with a few surrounding bases, which are replaced with the correct bases with the help of a DNA polymerase and the template DNA. When replication mistakes are not corrected, they may result
in mutations
, which sometimes can have serious consequences.
Which DNA polymerase does not proofread?
Polymerase α is responsible for the synthesis of the 20–30 nucleotides during Okazaki fragment initiation, that is further extended by lagging strand polymerase δ (Kunkel 2009; Kunkel et al. 1989). The fidelity of
DNA pol α
is low as this polymerase lacks its own proofreading (Kunkel et al. 1989).
What would be the expected outcome if the proofreading mechanism of DNA polymerase was not working properly?
The proofreading mechanism of DNA polymerase was not working properly. In DNA replication, the resulting daughter molecules contain one strand of the original parental DNA and one new strand. …
DNA in both daughter cells would be radioactive
.
What happens if DNA polymerase I does not work?
When strand slippage occurs during DNA replication, a DNA strand may loop out, resulting in the addition or deletion of a nucleotide on the newly-synthesized strand. … But if this does not occur,
a nucleotide that is added to the newly synthesized strand can become a permanent mutation
.
What foods help repair DNA?
One food shown to repair DNA is
carrots
. They are rich in carotenoids, which are powerhouses of antioxidant activity. A study that had participants eating 2.5 cups of carrots per day for three weeks found, at the end, the subjects’ blood showed an increase in DNA repair activity.
How does DNA polymerase fix mistakes?
Most of the mistakes during DNA replication are promptly corrected by DNA polymerase
by proofreading the base that has just been added
(Figure 1). In proofreading, the DNA pol reads the newly added base before adding the next one, so a correction can be made.
Why is RNA polymerase more error prone?
But the RNA polymerases of RNA viruses are the kings of errors – these enzymes screw up as often as one time for every 1,000 – 100,000 nucleotides polymerized. This high rate of mutation comes from the
lack of proofreading ability in RNA polymerases
. These enzymes make mistakes, but they can’t correct them.
Does DNA polymerase require a primer?
The synthesis of a primer is necessary
because the enzymes that synthesize DNA, which are called DNA polymerases, can only attach new DNA nucleotides to an existing strand of nucleotides. The primer therefore serves to prime and lay a foundation for DNA synthesis.
Is DNA polymerase 1 on leading strand?
DNA primase forms an RNA primer, and DNA polymerase extends the DNA strand from the RNA primer. DNA synthesis occurs only in the 5′ to 3′ direction. On the leading strand,
DNA synthesis occurs continuously
. … RNA primers are removed and replaced with DNA by DNA polymerase I.
What occurs in a deletion mutation?
A deletion mutation occurs when
a wrinkle forms on the DNA template strand and subsequently causes a nucleotide to be omitted from the replicated strand
(Figure 3). Figure 3: In a deletion mutation, a wrinkle forms on the DNA template strand, which causes a nucleotide to be omitted from the replicated strand.
What accounts for this important property of DNA?
DNA is a self-replicating molecule. What accounts for this important property of DNA?
A Its two strands are held together by easily broken covalent bonds
. … During DNA replication, the leading strand is synthesized continuously, whereas the lagging strand is synthesized as Okazaki fragments.
What happens when DNA is altered?
When a gene mutation occurs, the nucleotides are in the wrong order which means the
coded instructions are wrong and faulty proteins are made or control switches are changed
. The body can’t function as it should. Mutations can be inherited from one or both parents. They are present in the egg and/ or sperm cells.
Which is the lagging strand?
The lagging strand is
a single DNA strand that, during DNA replication
, is replicated in the 5′ – 3′ direction (opposite direction to the replication fork). DNA is added to the lagging strand in discontinuous chunks called ‘okazaki fragments’.
What happens if mutations are not corrected?
Most mistakes are corrected, but if they are not, they
may result in a mutation defined as a permanent change in the DNA sequence
. Mutations can be of many types, such as substitution, deletion, insertion, and translocation. Mutations in repair genes may lead to serious consequences such as cancer.
What problems can occur with DNA replication?
DNA replication is a highly accurate process, but mistakes can occasionally occur, such as a DNA polymerase inserting a wrong base. Uncorrected mistakes may sometimes lead to serious consequences, such as
cancer
. Repair mechanisms correct the mistakes.
