Molecular Genetics Flashcards
Cystic fibrosis
Loss of Phe residue at position 508
Results in trafficking failure of CFTR protein in epithelial tissue
Triplet repeat expansions
Huntingtons disease CAG repeat, poly glutamines changes the characteristics of the Huntingtin protein
Increased neuron decay rate
Mutations in poly(a) signals
Cancer susceptibility in AAUAAA –> AAUACA as prevents binding and cleavage and poly(A) machinery
Mutation in a-globin –> imbalance in subunits (excess a) –> aggregate haemoglobin –> affect RBC maturation and increased haemolysis –> thalassaemia
Cardiac Hypertrophy
Deletion of 5 nucleotides at critical region on TNNT2 gene
Renders 3’ splicing site unrecognisable, exon 4 shipped
TNNT2 gene –> troponin t in cross-bridge cycling, doesn’t function properly –> heart works harder
Tumour cells
Continual activity in tumour cells - telomerases to prevent chromosome shortening
Fanconi’s anaemia
Autosomal recessive: characterised by aplastic anaemia + cancer susceptibility
Failure of DNA repair as both strands damaged, so interstrand cross-links can’t be resolved
Particularly detrimental to rapidly dividing cells –> bone marrow
Anti cancer drugs
Eg methotrexate, 5-flurouracil
Stop cell division by interfering with dNTP supply
Degenerative muscular dystrophy
X-linked recessive
Related to structural protein dystrophin that connects cytoskeleton of each muscle fibre to basal lamina
Dystrophin gene codes for 79 exons
Exon 45 deleted disprupted reading frame, premature stop codon –> no functional protein
Sickle cell anaemia
Autosomal recessive
Glu6Val on B chain in haemoglobin (non-conservative, as results in Hb having different properties)
Hydrophobic soft spot on outside of protein structure causing aggregation and Sickling
Balanced polymorphism
Heterozygous have benefits - malaria protection, hence high frequency in Africa
