Messelson and Sthal's explained the model of semi conservative nature of DNA replication. According to this model, the newly synthesized DNA molecule contains one newly synthesized strand and one parental strand.
Firstly, bacteria grown in 15N media is transferred to 14N media. The isolated DNA is centrifuged and intermediate density DNA band is observed that contains one strand of 15N (parental strand) and one strand of 14N (newly synthesized strand).
Brief sequential change in the membrane potential of excitable cells after stimulus is called action potential whereas membrane potential represent charge difference across the membrane
In a typical neuron cell, membrane potential of cytoplasm is negative at rest and hence called resting membrane potential
Resting membrane potential of excitable cells is established by Na+ K+ pump and maintained by K+ leaky channels at rest
Phases of action potential includes: depolarization, repolarization, hyperpolarization and resting membrane potential
Depolarization starts when a threshold stimulus is applied on a neuron when via Na+ mechanically operated channels that trigger action potential
Depolarization of membrane potential is due to influx of Na+ via voltage gated Na+ channels
Repolarization starts with the efflux of K+ by the opening of voltage gated K+ channels, voltage gated K+ channels starts to open when voltage gated Na+ channels becomes inactive
Hyperpolarization occurs due to excessive efflux of K+ by voltage gated K+ channels
Additional efflux of K+ occurs due to slow inactivation of voltage gated K+ channel
Transporte activo, El Transporte pasivo es una gran estrategia para el movimiento de que la célula debe hacer es quedarse allí y dejar que las Moléculas se difundan a su interior. Por ejemplo, supongamos que tenemos una alta concentración de iones y sodio en el espacio extracelular(gracias al gran esfuerzo de la bomba sodio-potasio).
The generation time of that species would determine the time needed for bacteria in the culture to multiply to a sufficiently large number of cells that can be observed as visible colonies.
