Medicine Notes > Oxford Medicine Notes > Biochemistry Notes

Patterns Of Inheritance 1 Notes

This is a sample of our (approximately) 8 page long Patterns Of Inheritance 1 notes, which we sell as part of the Biochemistry Notes collection, a First package written at Oxford in 2014 that contains (approximately) 216 pages of notes across 33 different documents.

Learn more about our Biochemistry Notes

The original file is a 'Word (Docx)' whilst this sample is a 'PDF' representation of said file. This means that the formatting here may have errors. The original document you'll receive on purchase should have more polished formatting.

Patterns Of Inheritance 1 Revision

The following is a plain text extract of the PDF sample above, taken from our Biochemistry Notes. This text version has had its formatting removed so pay attention to its contents alone rather than its presentation. The version you download will have its original formatting intact and so will be much prettier to look at.

Introduction to medical Genetics Definitions Phenotype- physical description of a character in an individual organism (E.g-green pea) Character- structure/function/attribute determined by a gene or a group of genes Trait- alternate forms of the character Genotype- genes an individual has at a particular locus, it is responsible for the observed phenotype Penetrance- chance that a given genotype will cause a particular phenotype- usually referred to mutations "the chance the anjelina jolie who has the breast cancer gene will get breast cancer" Locus-a location of a gene within the genome of the individual Gene-inherited units of information that specify the phenotype at gross level and at a molecular level particular products such as proteins Genes and disease
-some disease are only due to genes- Achondroplasia is due to mutation of the FGF3 receptor which leads to premature differentiation of chondrocytes leading to shortening of the limbs.
-most diseases are due to the interaction of genes and the environment
-inability to metabolise phenylalanine (amino acid)-the protein accumulates in the brain and leads to mental retardation
-some disease are only due to environment- lead poisoning Modes of inheritance- SINGLE GENE DISORDERS!!!!
a)Autosomal dominant
-2 copies of a gene- only one needs to be mutated to get the disease, so manifests in the heterozygous state Pattern of inheritance: every generation is affected, male and females are equally affected, both males and females can transmit disease-chances of passing on the mutation is 50%
-heterozygotes are affected but is subject to penetrance of the mutation- in some cases the disease skips a

generation due to the penetrance of the disease which results in some cases non manifestation of the disease
-there is a variable manifestation of the dominant allele due to the expressivity E.g- Achondroplasia (Dwarfism)/Huntington's disease (damage of the nerve cells of the brain)/Marfan syndrome /familial breast cancer
-some autosomal disorders an affected person may have no family historythis could be due to a new mutation arising in the transmission b) Autosomal recessive
-2 copies of the relevant gene-both copies need to be mutated in order to inherit the disease
-heterozygotes are unaffected carriers
-chance of inheriting the disease from 2 carriers is 25%, there is 50% of being an unaffected carrier Pattern of inheritance: there is often a skipping of generation, the males and females are equally affected. It usually affects individuals in one generation in a single sibship and does not occur in previous and subsequent generations. Often people suffering from recessive conditions have parents that are blood linked-this is known as consanguinity- the genes are common by descent
-if a child is born from carriers but is unaffected the probability of being a carrier is 2/3 E.g- Tay-Sachs disease/cystic fibrosis/sickle cell anaemia/albinism

-Tay-Sachs disease is an autosomal recessive disease that is common in the Jewish populationleads to severe neurological degeneration-unable to walk/communicate normally
-Rachel and Lev are planning to have children-rachel's brother has TaySach's-what is the chance of Rachel inheriting the disease? 2/3 NOT 50% both parents will be carriers of the mtated gene so Rachel's genome could

****************************End Of Sample*****************************

Buy the full version of these notes or essay plans and more in our Biochemistry Notes.