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2021-05-14

What is the difference between base excision repair and nucleotide excision repair?

What is the difference between base excision repair and nucleotide excision repair?

Excision repair: Damage to one or a few bases of DNA is often fixed by removal (excision) and replacement of the damaged region. In base excision repair, just the damaged base is removed. In nucleotide excision repair, as in the mismatch repair we saw above, a patch of nucleotides is removed.

What does nucleotide excision repair fix?

In nucleotide excision repair (NER), damaged bases are cut out within a string of nucleotides, and replaced with DNA as directed by the undamaged template strand. This repair system is used to remove pyrimidine dimers formed by UV radiation as well as nucleotides modified by bulky chemical adducts.

How does nucleotide excision repair differ from base excision repair quizlet?

Nucleotide-excision repair reverses the chemical reaction that caused the lesion, whereas base-excision repair removes the damaged bases and replaces them with normal ones.

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What is the proper order of the steps involved in nucleotide excision repair?

Nucleotide excision repair

  • (i) recognition of a DNA lesion;
  • (ii) separation of the double helix at the DNA lesion site;
  • (iii) single strand incision at both sides of the lesion;
  • (iv) excision of the lesion-containing single stranded DNA fragment;
  • (v) DNA repair synthesis to replace the gap and.
  • (vi) ligation of the remaining single stranded nick.

What are the steps in base excision repair?

The repair process takes place in five core steps: (1) excision of the base, (2) incision, (3) end processing, and (4) repair synthesis, including gap filling and ligation.

What is the most common mechanism for repairing damage to DNA?

Most damage to DNA is repaired by removal of the damaged bases followed by resynthesis of the excised region. Some lesions in DNA, however, can be repaired by direct reversal of the damage, which may be a more efficient way of dealing with specific types of DNA damage that occur frequently.

What are the three major mechanisms of DNA repair?

There are three major DNA repairing mechanisms: base excision, nucleotide excision and mismatch repair.

What are the two types of DNA repair?

The different types of DNA repair include direct repair, base excision repair, nucleotide excision repair (NER), double-strand break repair (including homologous recombination and nonhomologous end joining), and crosslink repair (Sancar et al., 2004).

What causes double stranded DNA breaks?

The genome of a cell is continuously damaged, which is inevitable because DNA damage often arises as a result of normal cellular processes. The result is double-strand breaks (DSBs) in the chromosome. A DSB can also be caused by environmental exposure to irradiation, other chemical agents, or ultraviolet light (UV).

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What are the three steps of nonspecific DNA repair?

There are three types of repair mechanisms: direct reversal of the damage, excision repair, and postreplication repair.

What is the correct definition of excision repair?

A process whereby cells remove part of a damaged DNA strand and replace it through DNA synthesis using the undamaged strand as a template. The repair of a DNA lesion by removal of the faulty DNA segment and its replacement with a new segment.

What is a DNA repair enzyme?

Definition. DNA repair enzymes are enzymes that recognize and correct physical damage in DNA, caused by exposure to radiation, UV light or reactive oxygen species. The correction of DNA damage alleviates loss of genetic information, generation of double-strand breaks, and DNA crosslinkages.

What can change your DNA?

Environmental exposure to certain chemicals, ultraviolet radiation, or other external factors can also cause DNA to change. These external agents of genetic change are called mutagens.

Can medications change your DNA?

In other words, you can’t change your actual genes, but using drugs (and other choices you make) can influence which of your genes affect your health. These changes in gene expression can also be passed on to your children and grandchildren

Does your DNA change over time?

A study just out shows that as we get older, our DNA changes. A lot. Researchers in Iceland and the U.S. showed that over a period of 10-16 years, some people’s DNA changed as much as 20%. These differences aren’t in the famous A, T, C, and G’s of DNA though

How can your DNA be damaged?

DNA can be damaged via environmental factors as well. Environmental agents such as UV light, ionizing radiation, and genotoxic chemicals. Replication forks can be stalled due to damaged DNA and double strand breaks are also a form of DNA damage.

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How is DNA involved in vaccines?

DNA vaccines work by injecting genetically engineered plasmid containing the DNA sequence encoding the antigen(s) against which an immune response is sought, so the cells directly produce the antigen, thus causing a protective immunological response.

What are the advantages of DNA vaccines?

The main advantage of DNA vaccines is their ability to stimulate both the humoral and cellular arms of the adaptive immune system. In regards to humoral immunity, the generation of antibodies by B lymphocytes against invading pathogens is one of the most effective defenses mounted by the immune system

Is a DNA vaccine safe?

Despite initial concerns that they might integrate into patients’ genomes, DNA vaccines have proven remarkably safe; for instance, making them ideal in cancer immunotherapy or for vaccinating people with weakened immune systems, says David Weiner, Ph

Which vaccines are DNA based?

Infectious disease trials make up approximately 5% of the current open human clinical Phase I to Phase III trials testing the DNA vaccine platform and include vaccines against HIV-1, cytomegalovirus, and influenza virus.

What is a weakness of DNA based vaccines?

Disadvantages of DNA vaccines

Disadvantages of DNA vaccines References
DNA vaccines may have a relatively poor immunogenicity 31
Atypical processing of bacterial and parasite proteins 28
Insertion of foreign DNA into the host genome may cause the cell to become cancerous 25

What is the difference between recombinant vaccine and DNA vaccine?

How DNA Vaccines Differ from Recombinant DNA Vaccines. The immunogenic protein associated with a recombinant DNA vaccine is made in the laboratory and injected into the vaccine recipient, while the immunogenic protein associated with a DNA vaccine is generated by the cells of the host.