The Mitochondrial Chromosome Flashcards
Differentiate between the proeprties and significance of nuclear and mitochondrial chromosomes
Explain the organisation of DNA in the mitochondria
They have a circular chromosome which is replicated as they divide. Each mitochondrion contains 2-10 copies of its chromosome and it is not packaged into chromatin. It has a faster mutation rate is it is less accurately replicated. 16569bp long and codes 37 genes. No introns, genes are densely packed, no large intergenic regions.
Explain the function of the genes contained in the mitochondrial chromosome
The genes found in the mitochondrial chromosome are crucial for human health and life. 13 code for proteins used in ATP Synthesis, 24 code for RNA used in mitochondrial protein synthesis. These genes are essential for mitochondrial function but nuclear DNA encodes most of the proteins used in mitochondrial processes. Most of the genes encode tRNAs - smaller than protein coding mRNAS.
How can the mitochondria contain 10% of all human DNA if the mitochondrial genome is 0.001% size of nuclear genome?
There are 2-10 copies of the chromosome in each mitochondria, and 100-1000 mitochondria per cell.
What are the characteristics of a mitochondrially inherited disorder?
The inheritance is only through the maternal line - affected males do not pass on their genes.
Why do affected males not pass on their defective mitochondrial genes?
Because the sperm mitochondria do not enter the egg during fertilisation, the father can never pass on the mitochondrial mutation.
What is the main treatment for mitochondrial disease?
Mitochondrial replacement therapy - either pronuclear transfer or mitochondrial spindle transfer. PNT is fertilised egg pronucleus transferred into enucleated egg. MST is pre-fertilisation, nuclear material donated into healthy mtDNA donor egg.
