Innehållsförteckning
Hur adderas en nukleotid till en DNA sträng?
Det genomsnittliga antalet nukleotider ett DNA-polymeras adderar till den nya DNA-strängen innan det släpper från DNA:t kallas dess processivitet. Ju högre processivitet, desto fler nukleotider adderas till den nya DNA-strängen innan DNA-polymeraset ”släpper taget”.
Var sker replikation?
DNA-replikation är när DNA kopieras. Det sker i samband med celldelning, då arvsmassan ska föras vidare till ytterligare en cell. Det går till så här: Enzymet helikas binder till den position där den dubbla DNA-strängen ska öppnas – denatureras – och börjar öppna den dubbla DNA-strängen så att den blir enkel.
What is an example of facultative heterochromatin?
An example of facultative heterochromatin is X chromosome inactivation in female mammals: one X chromosome is packaged as facultative heterochromatin and silenced, while the other X chromosome is packaged as euchromatin and expressed.
What is the difference between euchromatin and heterochromatin?
Heterochromatin mainly consists of genetically inactive satellite sequences, and many genes are repressed to various extents, although some cannot be expressed in euchromatin at all. Both centromeres and telomeres are heterochromatic, as is the Barr body of the second, inactivated X-chromosome in a female.
What is the function of heterochromatin?
Heterochromatin has been associated with several functions, from gene regulation to the protection of chromosome integrity; some of these roles can be attributed to the dense packing of DNA, which makes it less accessible to protein factors that usually bind DNA or its associated factors.
What are the future investigations into heterochromatin assembly and maintenance?
Future investigations into assembly, maintenance and the many other functions of heterochromatin will shed light on the processes of gene and chromosome regulation. ^ Fisher AG, Merkenschlager M (April 2002).