GV1: DNA, Genes, Proteins and Diseases Flashcards
what are alleles
different forms of the same gene
dominant or recessive
some are phenotypic; some inherited mutant alleles can cause disease
what is an autosomal dominant allele
expresses itself in the phenotype of a heterozygous individual
what are some examples of diseases caused by autosomal dominant alleles
Huntington’s disease, hypercholesterolemia
what are autosomal recessive alleles
both parents must be at least heterozygous for condition and is therefore more common if parents are related
what are some examples of diseases caused by autosomal recessive alleles
sickle cell anaemia, cystic fibrosis, phenylketonuria
which gender is more likely to express X-linked recessive alleles
males; females must be homozygous
what are some examples of diseases caused by X-linked recessive alleles
haemophilia, colour blindness, Duchenne muscular dystrophy
what does SNP stand for
single nucleotide polymorphisms
what are SNPs
DNA sequesnce variation of a single nucleotide at same position in genome between members of the same species
each variant is an allele
they are stable and inherited
what can SNPs lead to
changes in amino acid codon which results in altered function
affects levels of expression of protein
affect where/when protein is expressed
what are the requirements for classification as a SNP
sequence variation must occur in at least 1% of the population
they provide info on predisposition to disease
how many SNPs do humans have
> 100,000
what does SSR stand for
simple sequence repeat (repeat of 2-8 base sequence)
where does gene mapping occur
at several different loci; looking for mutations in genes near to inherited markers
what is the definition of genomics
the science of the gene; a major constituent of molecular biology
