Genetics - Non-Mendelian Inheritance and Human Genome Project

Mitochondria have their own DNA and reproduce via fission, similar to bacteria.
Mitochondria rely on nuclear genes for some proteins but possess their own DNA.
Inheritance of mitochondrial DNA is 100% maternal; it is passed down from the mother through the egg cell.
Males do not pass on mitochondria.

Epistasis involves the interaction between two non-allelic genes, where one gene controls or interferes with the expression of another.
Example: Coat color in mice and dogs, where one gene determines black or brown fur (B gene), and another (C gene) controls the expression of the B gene.
$B$ gene: $B$ (Black - dominant), $b$ (brown - recessive).
$C$ gene: $C$ (allows pigment), $cc$ (no pigment, resulting in white or golden coat).
The $C$ gene is epistatic to the $B$ gene.
Step 1: Initial genes make a certain protein.
Step 2: The $C$ gene encodes an enzyme to convert the initial protein into black (if $B$ is present) or brown (if $b$ is present). The recessive $cc$ allele produces a dysfunctional enzyme that cannot perform the conversion, leading to no color.

The Human Genome Project aimed to sequence the entire human DNA to improve human lives, plant and animal products, and treatments for genetic diseases.
It was an international science project funded by multiple countries.
Initial goal: Determine the complete human DNA sequence (3.2 billion base pairs).
Started with sequencing viruses and bacteria, gradually advancing to more complex organisms.

Cystic fibrosis is a recessive genetic disorder caused by a specific mutation.
It affects the protein responsible for transporting substances in the lungs, leading to breathing difficulties due to water and phlegm accumulation.