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level: Level 1

Questions and Answers List

level questions: Level 1

Question	Answer
What is any change to the structure or quantity of the DNA of an organism known as?	Mutation
What does a mutagenic agent such as high energy ionising radiation do?	It can increase the rate of mutation
What effect does a deletion, addition, or duplication have on the DNA base sequence?	Produce a frame shift.
What is the general name given to undifferentiated cells in animals, including humans?	Stem cells
What are totipotent stem cells?	Cells that have the ability to differentiate into any type of cell.
How are pluripotent stem cells different from totipotent stem cells?	They can differentiate into all cells apart from those of the placenta
What is the source of totipotent stem cells?	Human embryos
What are iPS cells?	Induced pluripotent Stem Cells that have been genetically engineered from unipotent stem cells.
What is transcription?	The first stage of protein synthesis in which messenger RNA is produced from an exposed DNA sense strand.
What is the complex of proteins called that induce transcription after the move into the nucleus from the cytoplasm.	Transcription Factors
What enables the transcription factor to bind to the correct region of DNA?	A complementary binding site.
The presence of the female hormone oestrogen can enter a cell and instigate transcription - how does it enter the cell?	As it is a lipid-soluble, steroid hormone, it can easily diffuse through the phospholipid bi-layer of the plasma membrane.
When an oestrogen molecule binds to a TF, what happens to effectively "switch-on" transcription?	The binding site will change shape to make it complementary to the specific region of DNA so transcription can commence.
What are the heritable changes to DNA that do not effect of genetic code?	Epigenome
Chemical tags can form as a result of environmental factors on top of the genetic code. These affect the control of transcription and are of two main chemical groups which are?	Methyl groups and Acetyl groups.
A DNA-Histone complex forms chromatin i.e. "unraveled" DNA. in the cell nucleus. What are histones?	Proteins
What is the result of increased acetylation of histone proteins?	Looser, less condensed DNA with easer access to DNA for transcription factors.
What is the result of increased Methylation of DNA?	Tighter, more condensed DNA with reduced access to DNA for transcription factors.
As epigenetic changes can activate or silence specific genes, it follows that the protein enzymes that are key in methylation and acetylation provide a potential target for drug development. How could increased methylation result in tumour development	Increased methylation could result in reduced activity of tumour suppressor gene, leading to increased, uncontrolled cell division.
Another way of controlling protein synthesis is to target mRNA before translation with short double stranded lengths of RNA. What are these called?	siRNA's (Short interfering RNA's)