alleles Flashcards
what is an allele?
an alternative version of a gene
what is a gene?
a short section of DNA found on a chromosome
what does homozygous mean?
having two of the same alleles
what does heterozygous mean?
having two different alleles
what is a dominant allele?
it is an allele shown with a capital letter and if you inherit it, the characteristic is always seen
what is a recessive allele?
an allele shown with a lower case letter, you need to inherit two of them for the characteristic to be seen (aa)
what would two capital letters mean? e.g. AA
it is homozygous dominant
what would Aa mean?
heterozygous
what would two lowercase letters mean? e.g. aa
homozygous recessive
what is a phenotype?
a characteristic we see
what is a genotype?
a combination of alleles
what are inherited disorders?
disorders that are caused by a faulty allele
what is cystic fibrosis?
a disorder of the cell membranes
what is a symptom of cystic fibrosis?
thick sticky mucus and the lungs which leads to difficulty in breathing and lots of infections
what is cystic fibrosis caused by?
two recessive alleles e.g. aa or a carrier
what is polydactyly?
an inherited disorder
what is polydactyly caused by?
a dominant allele- only need 1
what are the symptoms of polydactyly?
an extra finger or toe
what are the advantages of embryonic screening? (3)
helps to stop people having inherited disorders
less expensive than treating disorders
only healthy embryos are implanted
what are the disadvantages of embryonic screening? (4)
parents may screen to pick most desirable embryo
embryos destroyed- some people think this is unethical
can trigger miscarriage,
expensive
who was gregor mendel?
an austrian monk who researched genetics
what were hereditary units?
genes
what are pea plant’s two phenotypes?
dwarf and tall
what was mendel’s first experiment and the results ?
crossed tall pea plants with dwarf pea plants - all plants turned out tall
