Topic 8 - Genotype, Phenotype And Inheritance PDF

🙆🏾‍♀️ Topic 8 - Genotype, Phenotype and Inheritance CBG - Group work Session 8.docx Lecture 1 - Mendelian Inheritance and Mitochondrial Genetics Genetic Terminology Mendelian inheri...

🙆🏾‍♀️ Topic 8 - Genotype, Phenotype and Inheritance CBG - Group work Session 8.docx Lecture 1 - Mendelian Inheritance and Mitochondrial Genetics Genetic Terminology Mendelian inheritance set of primary rules relating to the transmission of hereditary characteristics from parent organisms to the offspring What is recombination - Exchange of genetic material between homologous chromosome pairs, strands cross over Topic 8 - Genotype, Phenotype and Inheritance 1  Segments of DNA exchanged → Shuffling of genetic material Resolvase Enzyme Function Cleaves homologous chromosomes at Holiday Junctions to separate DNA Strands How do you calculate recombination frequency (Analysis of this allows estimation of the relative distance between two loci during recombination) number of recombinants/total number of meiosis Topic 8 - Genotype, Phenotype and Inheritance 2  1 cM (centiMorgan) is approximately equal to 1Mb (megabase) Symbols for genetic pedigrees What are the main characteristics of Autosomal dominant inheritance (AD) Each affected individual has at least one affected parent No skipping of generations Transmitted by either sex equally i.e. huntingtins disease, marfan syndrome Topic 8 - Genotype, Phenotype and Inheritance 3  Marfan Syndrome (AD) connective tissue disorder – patients very tall Caused by mutations in FBN1 gene What are the main characteristics of Autosomal recessive inheritance (AR) Both males and females can be affected If both parents affected, usually all children affected as well Affected individuals with normal partners have normal children Both copies of the gene have to be mutated for expression of the abnormal phenotype What 2 factors increase the risk of recessive disease? Both parents come from a high risk population Consanguinity (partners share an ancestor) What are the main characteristics of X-Linked Recessive Inheritance Mainly males affected since One mutant copy of the gene on the X- chromosome is sufficient to manifest the phenotype in males No male to male disease transmission Topic 8 - Genotype, Phenotype and Inheritance 4  What are the main characteristics of X-Linked Dominant Inheritance Either sex affected Usually at least one parent affected For an affected male, all of his daughters, but none of the sons are affected What are the main characteristics of Y-Linked Inheritance Only males affected All sons of affected father are affected Topic 8 - Genotype, Phenotype and Inheritance 5  Incomplete Dominance dominant allele does not completely mask the effects of a recessive allele, causing a mix Incomplete/non-penetrance Some mutation carriers may not show disorder features. Variable Expression People with the same genotype can exhibit different symptom severities. Anticipation Symptoms of a genetic disorder appear at a younger age in each new generation, often with increased severity. Mitochondrial Inheritance mitochondria is only inherited from the mother because only the head of the sperm is involved in the fusion with the oocyte if a female has a mitochondrial trait, all her offspring inherit it if a male has a mitochondrial trait, no offspring inherit it Topic 8 - Genotype, Phenotype and Inheritance 6  only 1 allele is present in each individual, so dominance is not an issue Define Heteroplasmy and Homoplasmy Heteroplasmy - there is a mixture of normal & abnormal mitochondria within each cell, Homoplasmy - mitochondria within a cell are the same-all normal or all mutant Mitochondrial DNA replacement therapy: 3 parent babies a method to prevent the passing of mitochondrial diseases from a mother to her child. It involves replacing faulty mitochondrial DNA in the mother's egg with healthy mitochondrial DNA from a donor. This way, the child inherits genetic material from three individuals, ensuring the child has functioning mitochondria Topic 8 - Genotype, Phenotype and Inheritance 7