Plant cells use transcription factors in a similar way to animal cells. One transcription factor found in plant cells is called PIF. When activated, PIF binds to the promoter region which triggers transcription of the amylase gene. PIF is inhibited by the presence of a repressor protein called DELLA. The plant hormone gibberellin stimulates the breakdown of DELLA to activate PIF. This process is shown in the diagram below.
Using the information above, suggest how the application of gibberellin hormone could facilitate the germination of seeds.
In the 1800s Jean Baptiste Lamarck published his theory of inheritance of acquired characteristics which suggested that an organism can inherit characteristics that had been acquired during its parent's lifetime. Lamarck’s theory has been much debated in the scientific world over the years, but more recently, advances in the understanding of epigenetics have led scientists to reconsider Lamarck’s ideas.
Outline how the field of epigenetics supports the theory of inheritance of acquired characteristics.
Epigenetic therapy could be used to treat diseases resulting from epigenetic changes by reversing changes to the acetylation of histones and methylation of DNA.
Suggest how knowledge of epigenetics could lead to the development of more effective treatments for diseases such as cancer.
A scientist obtained the mitotic index for a tissue sample taken from a patient.
Image courtesy of Nephron. Licensed under Creative Commons Attribution-Share Alike 3.0 Unported (CC BY-SA 3.0). Reused and distributed under conditions found at: https://creativecommons.org/licenses/by-sa/3.0/
i)
Define the term mitotic index.
[1 mark]
ii)
Suggest how the mitotic index could be used to indicate the presence of cancer in a tissue sample.
DNA methylation plays a vital role in gene regulation by affecting transcription. Tissue samples were obtained from two prostate cancer tumours (T1 and T2) and two normal prostate samples (X1 and X2). A specific gene was indicated as a plausible cause of cancer. The promoter of this specific gene was cloned several times (A–J). The data below shows the DNA methylation patterns from these samples. The numbers (29–271) represent different markers in the promoter region.
Use the information above to compare and contrast the methylation patterns in tumorous and normal tissue samples.
