Question

What are the 3 patterns of inheritance?

Answer 1

Inheritance is the process by which genetic traits are passed from parents to their offspring. Inheritance is the reason why parents and their offspring have similar characteristic traits. Some of the characteristic traits passed from parents to children in humans include eye colour, hair colour and blood type. The offspring gets one copy of the gene from each parent. The inheritance pattern is of three types.

Complete answer:
The three major patterns of inheritance of traits include autosomal dominant/recessive, X-linked dominant/recessive and mitochondrial inheritance.
Autosomal dominance refers to how a particular trait is inherited. Autosomes refers to the non-sex chromosomes. An autosomal trait is one that occurs due to a mutation on chromosomes from $1$ to $22$. Autosomal dominance denotes that only one allele is required from one of the parents for the trait to be observed in the offspring. The dominant allele conceals the effects of the recessive allele. Autosomal recessive inheritance means $2$ recessive alleles from each of the parents are passed onto the offspring. The traits may not be invisible in parents due to recessiveness but are visible in offspring due to combination.
X-linked dominant inheritance means that a gene responsible for a particular trait is located on the X chromosome, and only one copy of the allele is enough to pass on that trait to the offspring. X-linked recessive inheritance means the gene responsible for a trait on the X chromosome causes the phenotype to be always expressed in homozygous males and females. Females with only one copy of the inherited gene are carriers.
Since the mitochondria contain their own DNA, it can be inherited from the parent to the offspring. Mitochondrial DNA is only inherited from mothers.

Note:
Through inheritance, not only traits but also diseases and mutations are passed from the parents to the next generations. For example, Huntington disease, neurofibromatosis type 1, myotonic muscular dystrophy is inherited through autosomal dominance. Mitochondrial diseases are inherited through mitochondrial DNA from mothers. Some of the common X-linked inheritance disorders include rickets, Rett syndrome, color blindness, haemophilia A and B, Duchenne muscular dystrophy etc.