Biochemistry and genetics Flashcards
what does increased phenylpyruvate cause?
damages the brain and inhibits tyrosinase (the melanin making enzyme)
what is alkaptonuria caused by?
error in an enzyme involved in the tyrosine catabolism
what does phenylketonuria cause?
within the first few weeks of life –> can cause mental retardation, seizures, tremors and behavioural disorders
where is the CFTR gene located
on chromosome 7
what does CF lead to?
a build up of mucous in the lungs –> repeated chest infections –> lung damage Mucous also blocks the digestive system Reproductive systems also affected
what is the multiple repeat sequence of collagen
Gly-Pro-Ala
what mutation causes sickle cell anaemia and why does it cause problems
mutation of glutamate to valine the hydrophobic vlaine binds to a hydrophobic pocket present in deoxy-Hb and forms an insoluble crystalline structure
What causes esch-Nyhan syndrome? And what does if do?
Lack HGPRT enzyme- recycles purine for DNA synthesis Causes self mutilation
How is red-green colour blindness inherited?
X linked recessive
what causes CF?
defective cystic fibrosis transmembrane conductance regular gene (CFTR) –> codes for a chloride channel active in membranes of the lungs, liver, pancreas, intestines, reproductive tract and skin
what causes osteogenesis imperfecta
glycine to cysteine mutation - side chain of cysteine disrupts the helix as it doesnt fit in the middle - causes a kink and interferes with strand alignment –> brittle bones
what causes marfan syndrome
mutation in fibrillin 1 gene –> decreased production of fibrillin-1, delayed transport of the protein out of the cell, or reduced amounts of the protein in the ECM
how is CF tested for as an infant
the guthrie heel prick blood test - look for elevated immunoreactive trypsin secreted by the panreas Diagnosis then confirmed by sweat test (excessive NaCl)
what kind of inheritance is blue-yellow colour blindness
autosomal dominant
what is the mutation in the CFTR gene causing CF
a phenylalaine amino acid is deleted
what causes phenylketonuria
a build up of Phenylalanine due to the lack of phenylalanine hydroxylase enzyme –> causes it to go through an alternative metabolism where it is converted into phenylpyruvate
what makes collagen so strong
hydrogen from glycine project into the middle - forms hydrogen bonds
Mendels first and second laws
first - parents have 2 copies of a gene for a character second - different characters are inherited independently
how is PKU tested for?
the guthrie test - a dried spot from a heel prick = tested for phenylpyruvate and other metabolites
what causes albinism
genetic lack of tyrosinase –> this would usually go on to catalyse the synthesis of melanin
what are examples of one gene mutations involving collagen
osteogenesis imperfecta Ehlers danlos marfans
