Genetic inheritance

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Genetic inheritance is the transmission of genetic material from parents to children. Almost all physical features, many personality traits and unique abilities are present in genes.

A gene is the basic unit of heredity and contains a unique sequence-based nucleotide, bearing the information needed to make proteins essential to the body structure and function.

Genes are arranged on chromosomes. People have thousands of genes encoded in their DNA. Each of them plays an important role in a person’s life: some contain features simple, while complex traits involve more different genes.


1. Overview
2. Genes mutations
3. New mutations
4. Transmission of mutations

Genes mutations

Mutations occur only spontaneously. DNA is constantly damaged by normal processes, by the natural chemicals, radiation and sunlight. Damage is usually spotted, but occasionally may not be perfect repair. This can result from a mistake when DNA is copied while a cell divides, the mutation being caused.

Mutations can have three different effects:

- can be neutral and will have no effect
- can improve a protein and can be beneficial
- can result proteins that do not work and causing disease.

New mutations

Mutations can be inherited from a parent or may occur when a sperm or an ovum is created, causing new mutations. A person that will have a new genetic mutation, it will not show a family history of this condition.

Among the conditions that cause, often, new genetic mutations include:

- Duchenne muscular dystrophy – the most common and most severe muscular dystrophy
- hemophilia – a disease affecting the blood’s ability to clot.

Transmission of mutations

Eggs and sperm contain only one pair of chromosomes that are present in adults. Transmission of chromosome, from eggs and sperm, is random. If a mutation is present in only one of two copies of a gene (one pair of chromosomes), then there is a possibility of 1/2 to be inherited by the child.

- Recessive inheritance – For recessive inheritance, a child inherits a mutation in both copies of a particular gene. For this to happen, parents must have a copy of the defective gene and transmit it. When the child inherits only one abnormal copy of the gene, this one will be carriers of the disease. If parents transmit the abnormal gene, there is a possibility of 1/4 as their heir have genetic disorders. Cystic fibrosis is caused by a recessive gene.
- Dominant inheritance – In case of recessive inheritance, the mutation will be transmitted only from mother or the father only. If one parent has the condition, there is a possibility of 1/2 to be transmitted to the child. Neurofibromatosis type 1 is caused by a dominant gene. A child can inherit neurofibromatosis type 1 if either mother or father has the condition and sends the mutant gene. This may be caused by a genetic mutation including new.

- X-linked inheritance – If there is a mutation in a gene on chromosome X, the effect can’t be observed in women. This is because women have two chromosomes of which one is most likely normal. However, if a man chromosome X-linked inherited from his mother, he won’t have a normal copy of the gene and will develop the disease.



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