Non-Nuclear Inheritance
Biology: IB Diploma Higher Level, topic 15.1.1
Non-Nuclear Inheritance
Some phenotypes result from non-nuclear inheritance, which includes mitochondrial and chloroplast DNA.
Mitochondrial and chloroplast DNA
- Mitochondria and chloroplasts contain their own DNA.
- The DNA is circular and each mitochondrion or chloroplast has many copies of its DNA.
- During meiosis, chloroplasts and mitochondria are randomly assigned to the gamete daughter cells.
- This means the phenotypes controlled by mitochondrial and chloroplast DNA do not follow simple Mendelian inheritance patterns.
- Mitochondrial and chloroplast DNA is only ever passed from one parent.
Animals
- Mitochondrial DNA is maternally inherited in animals.
- This means the mitochondria in a fertilized zygote come from the ovum and not the sperm.
- Genetic disorders such a Kearns-Sayre syndrome are caused by mitochondrial mutations.
- Such syndromes are transmitted from affected mothers to any offspring.
- Paternal mitochondrial mutations are not passed on.
Plants
- Mitochondrial and chloroplast DNA is also maternally inherited in plants.
- Mitochondria and chloroplasts are transmitted in the ovule and not the pollen.
Test yourself on Non-Nuclear Inheritance
What shape is mitochondrial DNA?