Types of Mutagens-Phycial, Chemical (Base analog-5-bromo uracil) & Biological
Mutagenesis is the process of inducing mutation by a number of physical, chemical or biological agents.
The agents that causes mutation are called as mutagens. Mutation induced by mutagens is called induced mutation. Sometime mutation occur spontaneously due to error during DNA replication. However, mutagens increases the chances of mutation.
Physical mutagens:
Physical mutagens are X-rays and UV light.
X-rays, gamma rays, cosmic rays are ionizing radiation which ionizes water of the cell to release hydroxyl free radical (OH). The hydroxyl radical is a powerful oxidizing agent. Hydroxyl radical oxidises the phosphodiester bond of DNA. Higher dose of X-rays can even causes death of an organism.
UV light is a non-ionizing radiation. It causes the formation of thymine dimer (Pyrimedine dimer). If two thymine occur together in one strand of DNA, UV light causes fusion to form thymine dimer. Nitrogenous bases absorbs UV lights and the absorption is maximum at 260 nm. At the site of thymine dimer confirmation of DNA is changed, so rate of error during DNA replication is high.
Chemical mutagens:
three types of chemical mutagens are found.
i) Intercalating agent: The chemical intercalate or slip in between two base pair in Double stranded DNA helix and hence alter the morphology of DNA at that position. Chances of error during replication is higher at this position causing mutation. Examples; Acridine orange, ethidium bromide, proflavin
ii) Base analogue: These chemical are morphologically similar to that of normal nitrogen bases. So during replication these molecules are incorporated instead of normal nitrogen bases and hence causes mutation. Example; 2-aminopurine is analogue to Adenine, 5-bromourcail is analogue to thymine
iii) Reacting chemicals: These chemical mutagens reacts directly with the nitrogenous bases of DNA and chemically modify the DNA causing mutation. Example; Nitrous acid react with nitrogenous bases and remove amino group from purine and pyriminine.
Biological mutagens:
transposons and insertion sequence (IS) elements are biological mutagens. Examples; mutator gene, bacteriophage MU etc.
Transposons and IS elements are small sequence of DNA that moves from one site to another along DNA strand and causes mutation. Transposons and insertion sequences are also known as jumping gene. These sequence contains gene which codes the enzyme transposase which helps in transposition of these sequence from one site to other.
IS element are simplest type of transposable element. They are short DNA about 1000 nucleotide long and typically contains inverted repeats of 10-50 base pair. The only gene they poses is the gene for enzyme transposase. IS element are found in both chromosome and plasmid of both bacteria and Archea as well as some bacteriophage.
Transposons are larger than IS element but similar as IS element because it also has two essential component; contains inverted repeats and encodes transposases.
Пікірлер: 46
V.Easy to understand and whole topic covered in only 12 mins. Which usually take one and half hour to understand thanku mam
@BioMagica
3 жыл бұрын
Glad you liked it. Do share
@Aamirintwala
3 жыл бұрын
@@BioMagica lplp
One of the best I have seen.....thank u mam........gained some knowledge coz of u.......!!!
@BioMagica
5 жыл бұрын
😊😊
U explained this tough topic in very easy way ...thank u ma'am
@BioMagica
5 жыл бұрын
Thanks 😊
Thank you for the explanation
Thanks for the explanation........
Thank you so much 🙏🏽
Thank u mam it really helped me 4 my one day before xam preparations..
@BioMagica
4 жыл бұрын
Happy to help 😊😊😊
Ma'am the way you explain its very easy to understand
@BioMagica
3 жыл бұрын
Glad you liked it. Do share
Thank you so much ma'am ❤❤
Thank you very much!
@BioMagica
Жыл бұрын
Happy to help 😊
great explanation . plz include the endogenous cases too as all of the above causes were only exogenous
@BioMagica
3 жыл бұрын
sure. do share
great explanation . plz include the endogenous cases too as all of the above causes were exogenous .
@BioMagica
3 жыл бұрын
sure. do share
thank you mam
@BioMagica
5 жыл бұрын
😊😊😊
👍👍👍 Thanks mam
@BioMagica
3 жыл бұрын
Happy to help 😊
👍
@BioMagica
3 жыл бұрын
thanks
0:44
Background music is irritating, please try to avoid it
@BioMagica
2 жыл бұрын
Yes I realized it later. Removed it on future videos
madom notes ka link send kar sakti hain ap
..on THHAA ...
U also have to tell about normal is keto form and rare is enol form... Otherwise nice
@BioMagica
5 жыл бұрын
Okay. Thanks
Aarey mam backgorund music toh bandh karro...🤦🏻♀️🤦🏻♀️
@BioMagica
3 жыл бұрын
Yes sorry I realized later that it was quite loud. Will reupload without music asap. Thanks for the feedback 😊
No entendi nada. :((((((((((((((( Soy malisimo.
@BioMagica
Жыл бұрын
If you do not understand from this video does not mean u r bad...maybe my way of explanation was not appropriate for you...Look up for other videos. Hopefully you will find something that can help you out 😀
You have just copy pasted russell 😂
@BioMagica
5 жыл бұрын
Thank you. The channel is meant to assist students to understand concepts. And obviously, the content will come from a genuine source. I hope it was useful 😊
great explanation . plz include the endogenous cases too as all of the above causes were only exogenous
@BioMagica
3 жыл бұрын
sure. do share
great explanation . plz include the endogenous cases too as all of the above causes were only exogenous
@BioMagica
3 жыл бұрын
sure. do share
great explanation . plz include the endogenous cases too as all of the above causes were only exogenous
@BioMagica
3 жыл бұрын
sure