If DNA gets damaged, it can be repaired by various mechanisms, including chemical reversal, excision repair, and double-stranded break repair
.
What happens if DNA repair genes are mutated?
When erroneous DNA repair leads to mutations or chromosomal aberrations affecting oncogenes and tumor suppressor genes,
cells undergo malignant transformation resulting in cancerous growth
.
Does DNA repair fix mutations?
(B)
DNA repair corrects mutations
(more…) Both mutation and recombination can have dramatic effects on the cell in which they occur. A mutation in a key gene may cause the cell to die if the protein coded by the mutant gene is defective (Section 14.1.
What are the consequences of defective DNA repair and mutation?
Generally speaking, the consequences of DNA repair defects are
microcephaly or neurodegeneration
. While both pathologies ultimately result from cell loss, the fundamental underpinnings are different. Microcephaly results from cell loss or proliferation defects during neurogenesis.
How does DNA mismatch repair work?
Mismatch repair happens right after new DNA has been made, and its job is to
remove and replace mis-paired bases
(ones that were not fixed during proofreading). Mismatch repair can also detect and correct small insertions and deletions that happen when the polymerases “slips,” losing its footing on the template 2.
What mechanisms can repair DNA?
At least five major DNA repair pathways—
base excision repair (BER), nucleotide excision repair (NER), mismatch repair (MMR), homologous recombination (HR) and non-homologous end joining (NHEJ)
—are active throughout different stages of the cell cycle, allowing the cells to repair the DNA damage.
What is DNA damage and DNA repair?
The pathway of cellular DNA damage and repair that leads to senescence, apoptosis, or cancer
. To compensate for the degree and types of DNA damage that occur, cells have developed multiple repair processes including mismatch, base excision, and nucleotide excision repair mechanisms, with little process redundancy.
Do DNA repair genes inhibit cell growth?
Unrepaired or incorrectly repaired DNA damage can lead to serious genome aberrations or mutations, potentially affecting cell survival [4]. However,
some mutations change cell proliferation due to defects of certain genes
, e.g., oncogene, a tumor-suppressor gene, or a gene that controls the cell cycle.
How does DNA damage lead to mutation?
When DNA carrying a damaged base is replicated, an incorrect base can often be inserted opposite the site of the damaged base in the complementary strand, and this can become a mutation in the next round of replication. Also DNA double-strand breaks may be repaired by an inaccurate repair process leading to mutations.
What might happen to an organism whose DNA is damaged through mutation?
How can mutations affect organisms? Mutations can affect an organism by changing its physical characteristics (or phenotype) or it can impact the way DNA codes the genetic information (genotype). When mutations occur
they can cause termination (death) of an organism or they can be partially lethal
.
Which of the following condition is caused by DNA repair mechanism impairment?
Today, a limited number of rare hereditary diseases characterized by genetic defects of DNA repair mechanisms is known, comprising
ataxia telangiectasia, Nijmegen breakage syndrome, Werner syndrome, Bloom Syndrome, Fanconi anemia, xeroderma pigmentosum, Cockayne syndrome, trichothiodystrophy
.
Why are functional DNA repair mechanisms are crucial for the continued survival of cell?
DNA repair ensures the survival of a species by
enabling parental DNA to be inherited as faithfully as possible by offspring
. It also preserves the health of an individual. Mutations in the genetic code can lead to cancer and other genetic diseases.
What type of DNA damage or error does mismatch repair fix?
1 Mismatch Repair. MMR mainly repairs
DNA lesions caused by faulty DNA replication or repair
, resulting in mismatches or small insertion and deletion loops, or deamination of 5-methylcytosine. Failure of MMR is often associated with point mutations or microsatellite instability (Fig.
Is DNA mismatch a mutation?
| Cancer type Frequency of deficiency in cancer Frequency of deficiency in adjacent field defect | Stomach 32% 24%-28% |
|---|
How are DNA replication mistakes corrected?
Most of the mistakes during DNA replication are promptly corrected
by DNA polymerase by proofreading the base that has been just added
(Figure 14.6. 1). In proofreading, the DNA pol reads the newly added base before adding the next one, so a correction can be made.
Which of the following DNA repair mechanisms does not use a template DNA?
Which of the following DNA repair mechanisms does NOT require a DNA template? Homologous recombination uses sister chromatid as a template to repair the break.
Non-homologous end joining
does not rely on a template.
What happens if your DNA is destroyed?
Genes that repair other damaged genes (DNA repair genes)
Most DNA damage gets repaired straight away because of these proteins. But if the DNA damage occurs to a gene that makes a DNA repair protein, a cell has less ability to repair itself. So
errors will build up in other genes over time and allow a cancer to form
.
What is the role of DNA repair genes?
These genes function in a diverse set of pathways that involve the
recognition and removal of DNA lesions, tolerance to DNA damage, and protection from errors of incorporation made during DNA replication or DNA repair
.
