This is a Clilstore unit. You can .
0:00 Have you ever wondered what determines
0:01 your height hair and skin colour and even
0:04 the size of your nose? Its DNA, the
0:08 genetic material of cells. But do you know
0:10 how it has been proved? Here is the
0:13 experiment that proved it: Griffith’s
0:15 experiment. Griffith took two strains of
0:18 Pneumococcus bacteria SIII, which have
0:21 smooth polysaccharide capsule, giving
0:24 smooth colonies (S), and its virulent
0:26 causing pneumonia; and RII, which have no
0:30 capsule, giving rough colonies (R) and is
0:33 avirulent, unable to cause pneumonia.
0:35 When the virulent SIII bacteria injected
0:38 in mice, it killed them, causing pneumonia.
0:41 But when the avirulent RII injected in
0:44 mice, the mice lives. if you injected the
0:47 heat killed virulent SIII bacteria, the
0:50 mice still live implying that live SIII
0:53 bacteria are needed for causing
0:55 pneumonia. But interestingly when mice
0:57 were injected with the mixture of heat
0:59 killed virulent SIII bacteria and
1:01 avirulent RII bacteria, mice died.
1:04 Analysis of dead mice reveals live SIII
1:07 virulent bacteria suggesting something
1:10 from the heat killed SIII had transformed
1:12 the live avirulent RII bacteria
1:15 responsible for the transformation of
1:17 the live avirulent bacteria to virulent
1:20 SIII bacteria, causing death of mice. This
1:23 is called as bacterial transformation. To
1:26 prove DNA is genetic material team of
1:29 Avery et al and Hershey and Chase
1:31 performed other experiments.
Short url: https://multidict.net/cs/5124