9. Briefly describe how each of the following mutations would affect gene expression and/or phenotype: Reactive oxygen species have resulted in numerous G->A transitions in various mitochondria-encoded tRNA genes.

Explanation:

1. Defective Mitochondrial Gene Expression Results in Reactive Oxygen Species (ROS).

2. Elevated production of reactive oxygen species (ROS), and increased oxidative stress, results in defects in proper functioning of cell by causing mutation in the DNA and mitochondrial genes.

3. If the mutation is silent mutation, then there is no harm or less harm in the cell, if the mutation is missense or nonsense type then it can affect the functioning of the cell and phenotype of that organism.

4. If their is mutation in mitochondrial tRNA gene, it can affect the translation of mitochondrial mRNA and gene expression.