In this article we will discuss the chemical and physical types of Mutagenos.
1. Chemical mutagenous:
Singer and Kusmierek (1982) published an excellent overview of the chemical mutagenesis.
Some of the chemical mutations and mutagenesis appear in Table 9.3 and are described below:
A basic analogue is a chemical compound that resembles one of the four DNA bases.These connections have different basics of base pairing. They replace the basics and cause a stable mutation.
A very common and widespread basic analog is 5-bromouracil (5-BU), an analogue by Timina.5-Fu functions such as Timina and couples with adenine (Fig. 9.6a).
The 5-BBE suffers a tautomer change in the ketoform to the enol form caused by the bromate. The enol form can exist for a long time, up to 5 times for Timina (Fig. 9.6b).During the replication, which in turn indicates cytosine, the G: C torque causes (Fig. 9.6a).
During the replication, the key shape of 5 BM is replaced by t and the replication of an initial couple in the couple will be a couple for: BU (Fig. 9.7a). Mutagener replication step.Completed the couple → GC.
5-FU can also induce GC when converting. ENOL often acts as an analogue of cytosine instead of shyness. It is a couple (Fig. 9.7b).A Guanin torque disturbs the normal process of replication of the microorganism.
5-bromodoxiuridine (5-BDU) can replace timidine in the DNA molecule. Purinaoder 2-A is usually combined with Timina, but can form a single connection of hydrogen cytosine, which can form for the transition from GC.O 2-AP and 2,6-dap is not as effective as 5-BU and 5 -BDU.
II. Chemicals that change the specificity of hydrogen binding:
There are many chemicals that change the specificity of hydrogen after installation in the DNA.2), Hydroxylamine (ha) and ethyl --- queconate (EMS).
The laugh oxide converts the amino group of group groups, which through oxidative disassembly.
(B) adener -samination:
The acceptance of adenin leads to the formation of hypoxantine, the mature behavior of the behavior like guanin.
(C) Cytosin Demation:
Cytosin transformation leads to Uracilo -NH substitute formation2Group with the group -OH group.
The expression of guanin leads to an Xantine formation, the rear tradition is not mutagen.MebehaVado Negro as guanina because there are no changes in the behavior of the mating. The couples of Xantina with cytosine.
Hydroxilate c4The nitrogen of the cytosine and becomes a modified basis for the detached, which causes couples of bases such as tyamine.
III. Alkylierende Adagents:
Add an oxygen to the hydrogen fork group (N.7Position) and adenine (in n n n n n n n3Position) DNA residues are carried out by rented agents. The consequence of the alkylation does the possibility of ionization in the introduction of matches. The hydrolysis of the basic sugar connection occurs, which leads to a gap in a chain.
This phenomenon of the loss of the rented DNA molecule (due to the union that combines nitrogen from purine and deoxyribosis) is referred to as deputies. The deputy is not always mutagen. The gap that arises from the loss of a purine can be effectively repaired.
Next, some of the widespread important alkylation agents:
(a) Dimetilsulfato (DMS)
(B) Ethylsulfonato -Methan (EMS) -Ch3Pez2SO3Pez3
(C) Ethanethan -Sulfonato (EES) -Ch3Pez2SO3Pez2Pez3
The EMS has to remove the specification of eliminating guanine and cytosine of the chain, and leads to the formation of gaps.The second round of the replication room is properly filled.
If the correct basis is inserted, the normal DNA sequence occurs. The introduction of the wrong base leads to a transversion or transition mutation. An example is nitrosoguanidin -methyl, which adds the methilian group to Guanin, which leads to it that it leads to itto the titamine.
4. Agers exchanged:
There are certain dyes such as acryidinorange, proclavin and acriflavin, the three ring -like molecules that are similar to those of pyrimidine pyrimidine pairs (Fig. 9.9). In aqueous solution, these dyes can in the DNA (i.e. internal intermediate the DNA) between the foundationsTo be inserted, two of them are next to a process called interalation.
Therefore, dyes are referred to as interpersse agents. Acridine are flat (flat) molecules that can be interspersed in DNA base pairs; the exclusion or insertion of exchanged active ingredients occurs in exchange for frames (Fig. 9.10).
2. Physical mutas:
I. Radiações Als Mutagener:
The radiation is the most important under the mutagen of the physical radii -mutagenik -Mutagenik for DNA molecules in the wave of the wave of 340 and photos for 1 volunteer electr (eV).Rays, Alpha, Alfa, Alfa, Alpha, Thigh, Beta (α) ray (α) ray (β), neutron etc. (Fig. 9.11).
Radiation-related damage can be divided into the three large types: deadly damage (killing organisms), possibly fatal damage (can be fatal on certain frequent conditions) and sub-salad damage (cells do not die, unless the radiation reaches a certain threshold)) The effect of the damage is on the molecular level.
In radiation damage to lively protein cells, lipoproteins, DNA, carbohydrates etc. are caused directly by ionization/suggestion or indirectly by high -reactive free radicals that are generated by cell water radius.
If bacteria are exposed to radiation, they gradually lose the ability to develop colonies. The gradual loss of liability can be expressed graphically, which means that the surviving colonies against the exposure period of gradual growth is referred to.occurs in Fig. 9.12. The survival curve is analyzed by a simple mathematical theory, which is referred to as success.
Each organism has at least a sensitive place known as the destination. Radiation photons (light particles) damage or reach the target and inactivate organisms. It can be derived from equation based on this theory.
The equations contribute to calculating the survival curve for many types of populations of identical organisms that are exposed to the D -dose D and cause damage.
K is the constant that measures dose effectiveness.
Integrate this equation of n = no at d = o, we get us
N = NrE-KD… (1)
The surviving faction S = n/is not
S = n/no = y-Kd… (2)
A D virus table offers a straight line with a tendency of -k (Fig. 9.12). This type of curve is referred to as an exponential curve or a single blow..
If there is a population of different organisms and every organism consists of at least local N, every location must be reached to inactivate an organism., P = 1-e-Kd) Therefore, the likelihood of PN PN = (1-e-Kd)Norte
The surviving part of the population is 1 PN or S = 1- (1-e-Kd) n ... (3)
This equation can be expanded as:
C = 1- (1-nr.-Kd+ E-NKD)
In the great value of D, the conditions of the higher order are insignificant compared to a high D dose, compared to a high D dose
C = Nr-KdÖ
Em s = em n - kd ... (4)
If equation 3 is drawn to K - 1, several values of N show that for small values from D in S is gradually changing (Fig. 9.13). In a great value, equation 4 and the curve becomes linear.
Ii.ultraviolet radiation (UV):
UV radiation leads to damage to the duplex -DN of bacteria and phagos.UV rays are absorbed and cause macromolecular excitement, but not protein. The RNA absorption spectrum is rather similar from DNA.
The lively DNA leads to reticulation, the unique wire breaks and the basic damage such as the slight injury and the generation of nucleotide diameters than important.
Therefore, the proportion of Timina (TT), Timina-Ecitosin (TC), Cytosin (CC) (Fig. 9.14) 10: 3: 3.es also appear some dimers of them and the first step is knownIn the pimidindimension, the hydration of its connections is 4: 5.
Timin-Ess formation (TT) causes a DNA propeller distortion because young people are thrown together.
X -rays cause Easter phosphate compounds for the DNA. This break takes place on one or more points. A large number of bases in the DNA molecule are excluded or reorganized.
X -rays can break down the DNA into one or both cables. If it occurs in both cables, it becomes fatal. The DNA segment between the two breaks is removed, which leads to exclusion.Sterilization of bacteria and viruses used.
- Difference between DNA and RNA
- Mutagen types: radiation and chemical products | genetics