HL 2 Biology

D.1b: Origin of Life: RNA World

<<Protobionts and the role of RNA>>

protobionts: structure with a different internal chemistry from their surroundings

  • packaging of abiotically produced molecules into protobionts = necessary stage in origin of cells
  • exhibits properties associated with life; response to environment, simple reproduction, basic metabolism, etc.

RNA: self-replicating + its catalytic properties make it the most likely original molecule of inheritance

================DBQ==========================

RNA (p. 309)

1) In experiment A, exposing the labelled empty vesicles and vesicles containing RNA both decreased in their relative surface area over time. Yet it is evident that the unlabeled empty vesicles have shown a slow and more gradual decline in surface area compared to the steeper and quicker decline in surface area for the vesicles containing RNA. In between 0-10 minutes, the decline in relative surface area for the vesicles containing RNA is greatest. 

2) In experiment B, the exposure of labelled vesicles containing RNA and unlabeled empty vesicles had both shown an increase in relative surface area over time. The empty vesicles however, has shown a faster rate in the increase of surface area over time compared to the labelled empty vesicles containing RNA. THe empty vesicles had the steepest incline in surface area through the first 10 minutes and gradually became a plateau from 20-40 minutes.

3) The conclusion that vesicles containing RNA can take membrane material from vesicles that do not contain RNA can be supported by these experiments. In experiment A, it shows an decrease in the surface area of empty vesicles whereas in experiment B, it shows an increase in the surface area of the vesicles with RNA.   With the evidence of the surface area of the empty vesicles declining while the surface area of vesicles with RNA increase, it supports the conclusion that the membrane material were to be taken out of the empty vesicles.

4) Vesicles containing RNA would become more common because of its ability to self-replicate and how it contains catalytic properties. As the empty vesicles continued to take the membrane from the vesicles with RNA, the empty vesicles will continue to decrease in size and may be less adaptable into its environment. The ability to self-replicate may have enabled the vesicles containing RNA to outcompete the vesicles which lack RNA as it may continue to self-replicate and blend into its environment.

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