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Timing:5.30 pm to 9.30 pm
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313th day of CUBE ChatShaala: 31st January 2021
19 CUBists from 18 Centres had joined the webinar
Map
DELHI
AND College: Dr Sarita Kumar
HARYANA
Faridabad: Rahul Kushwaha
JHARKHAND
Kanke, Ranchi: Ram Deepak
Ranchi: Sweta Ranchi
KERALA
Thriprayar, Thrissur: Aswathy Suresh
Palakkad: Neeraja Nair, Sukanya P
SN College, Nattika: Seethalakshmi CR
MAHARASHTRA
South Bombay: Arunan MC
Nerul: Drishtant M Kawale
Worli, Mumbai: Isha Pawle
Mahad, Raigad: Manasi Prasad
Dahanu, Palghar: Sachin Pradhan
Bandra, Mumbai: Saida Sayyed
Murbad, Kalyan: Shubham Isame
UTTAR PRADESH
Kanpur: Hina Mudgal
Moradabad: Kiran Yadav
WEST BENGAL
Kolkata: Batul Pipewala
Garden High School, Kalyani: Koulab Mukherjee
In today’s discussion, we talked about Moina and its mode of reproduction Moina water flea found in freshwater bodies like ponds and lakes reproduces parthenogenetically that is asexually And in harsh conditions like low oxygen level or overcrowding, it changes its mode of reproduction to sexual So the question arises how is sexual reproduction helping Moina survive the harsh condition
Maybe through variation
In asexual reproduction The organism sorts of cloned them self but we cannot call it cloning because there’s always a chance of mutation
Two such mutations.
- Mutation occurring during DNA replication
- Mutation occurring due to mutagens like UV radiation
During DNA replication DNA polymerase reads DNA in 3 to5 direction and makes The stand-in 5 to3 direction So one of the stands formed is in continuous The other stand for which template is 5to 3 The DNA is formed in small stands in a discontinuous form called as Okazaki fragments So the chances of mutation on this fragment increases as the DNA is not read continuously Also, there are proofreading mechanisms which will rectify any mutation that has occurred but the mutation may surpass the proofreading So there are chances of mutation but it is less also there are various types of mutation sometimes mutation can occur on junk DNA which is not coding for any protein so though there are no phenotypic changes such there is mutation occurred
Another type of mutation through mutagens When an organism is exposed to UV radiation it can cause mutation even though the DNA is not replicating For example, UV radiation can break the hydrogen bond between the base pairs and form a dimer that is pair among is the bases like thymine dimmer which can be rectified by the cell through nucleosome excision repair mechanism When the amount of UV radiation is increased it’s more such dimer would be formed and it could be such that this dimer may form on the genes which are important for cell division which may cause the cell to become cancerous
Coming back to from where we started and variations can be caused through mutation but the chances of it are less but in sexual reproduction, variation occurs in Miosis when crossing over takes place
