In normal healthy cells the LexA protein binds to a certain section of the bacterial DNA called the ‘SOS box’ which codes for over 50 genes while RecA floats around the cell looking for damaged DNA. If it finds any, it binds to it and stimulates the breaking of the LexA protein.
How is DNA damage detected and repaired?
Breaks in DNA reduce the molecular weight of a single DNA strand, and this may be caused by physical, chemical or enzymatic reagents (6).
DNA breaks and lesions may be detected by PCR or using agarose gel electrophoresis
(7). PCR is one of the most frequently used techniques for detecting DNA damage (7).
How do bacteria protect genome from damage?
To defend against a phage attack, bacteria have
evolved a variety of immune systems
. For example, when a bacterium with an immune system known as CRISPR-Cas encounters a phage, the system creates a ‘memory’ of the invader by capturing a small snippet of the phage’s genetic material.
What are the different mechanisms that bacteria can use to repair their damaged DNA?
There are three types of repair mechanisms:
direct reversal of the damage, excision repair, and postreplication repair
.
What is DNA damage and DNA repair?
DNA repair is
a collection of processes by which a cell identifies and corrects damage to the DNA molecules that encode its genome
.
What are the DNA repair mechanisms?
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 are three ways that DNA gets damaged?
DNA damage occurs continuously as a result of various factors—
intracellular metabolism, replication, and exposure to genotoxic agents, such as ionizing radiation and chemotherapy
. If left unrepaired, this damage could result in changes or mutations within the cell genomic material.
What is the repair mechanism for damaged DNA caused by a chemical mutagen?
Cells also have two major mechanisms for repairing Double-Strand-Breaks (DSBs). They include
Non-Homologous End-Joining (NHEJ) and Homologous Recombination (HR)
. If damage is too extensive to be repaired, apoptotic pathways will be elicited.
Can usually repair DNA damage caused by ultraviolet light?
Because
most UV damaged DNA is efficiently repaired by nucleotide excision repair (NER)
, which is a specialized UV-induced DNA damage repair system, many UV-induced symptoms are closely related to NER.
Do bacteria have DNA repair?
In bacteria,
there are two general mechanisms for repair of DNA breaks: non-homologous end-joining (NHEJ) and homologous recombination
. In some species of bacteria, the broken DNA ends can be joined directly in a manner analogous to the NHEJ pathway seen in eukaryotes
2
.
What enzymes are needed for efficient repair of the damaged DNA?
Apurinic/apyrimidinic (AP) endonuclease 2 (Apex2)
is well-known as an essential DNA repair enzyme that plays a critical role in DNA repair against the oxidative damage in a variety of cells. It has been reported that AP sites occur in DNA molecules by spontaneous hydrolysis, DNA-damaging agents or by DNA glycosylases.
How does a bacteria protect its own DNA from being cleaved by restriction enzymes?
Bacteria prevent cutting their own DNA by
masking the restriction sites with methyl groups
(CH3). The methylation process is achieved by the modification enzyme called methyltransferase. Bacterial DNA is highly methylated and is unrecognizable for the restriction enzymes, thus being prevented from cleavage.
What is direct repair of DNA?
Introduction. Direct repair is defined as
the elimination of DNA and RNA damage using chemical reversion that does not require a nucleotide template, breakage of the phosphodiester backbone or DNA synthesis
.
What are the two types of DNA repair?
There are two general classes of DNA repair;
the direct reversal of the chemical process generating the damage and the replacement of damaged nucleotide bases
. DNA encodes the cell genome and is therefore a permanent copy of a structure necessary for the correct functioning of a cell.
What happens DNA damage?
DNA damage in non-replicating cells,
if not repaired and accumulated can lead to aging
. DNA damage in replicating cells, if not repaired can lead to either apoptosis or to cancer.
How can I repair my DNA naturally?
Exercise on the reg
. Regular physical exercise increases antioxidant capacity, protects DNA and reduces the effects of age-related declines in DNA repair. In one study, 16 weeks of physical exercise dramatically increased antioxidant activity, decreased DNA strand breaks and promoted DNA repair.
Does an organism have ways of repairing such damage?
Organisms have developed several DNA-repair pathways as well as DNA-damage checkpoints
to cope with the frequent challenge of endogenous and exogenous DNA insults. In the absence or impairment of such repair or checkpoint mechanisms, the genomic integrity of the organism is often compromised.
What are the two types of DNA repair quizlet?
- spontaneous deamination: C forms U, A forms hypoxanthine, G forms xanthine.
- spontaneous depurination: lose a base entirely and form “AP site”
- oxidizing agents: damage by reactive oxygen species (ROS)
- alkylating agents.
Why is DNA repair important?
DNA Repair Pathways and Human Cancer
DNA repair is central to the field of cancer biology, and
it has important implications for cancer diagnosis and treatment
. Cancer cells are often deficient in a normal DNA repair function, and this deficiency allows the tumor to develop genomic instability.
What are the types of DNA damages?
DNA damage can be subdivided into two types: (1) endogenous damage caused by reactive oxygen species (ROS) that are derived from metabolic byproducts and (2) exogenous damage caused by radiation (UV, X-ray, gamma), hydrolysis, plant toxins, and viruses.
Why is DNA damage repaired before cells enter mitosis?
Ideally, if DNA damage is detected, the cells do not enter mitosis until the damage is repaired. Why is DNA damage repaired before cells enter mitosis?
So that healthy daughter cells are produced, allowing the organism to continue to grow
.
How do we know that DNA repair mechanisms detect and correct the majority of spontaneous and induced mutations?
Cells have a variety of mechanisms to prevent mutations, or permanent changes in DNA sequence. During DNA synthesis,
most DNA polymerases “check their work,” fixing the majority of mispaired bases in a process called proofreading
.
What kind of DNA repairing mechanisms are present in embryonic cell?
There are two major pathways for DNA DSB repair. These are:
homologous recombination-mediated repair (HRR) and nonhomologous end-joining (NHEJ)
.
