section 2: patterns of inheritance - topic 2: genetic terms Flashcards
what is a gene?
a sequence of bases on a DNA molecule that codes for a protein (polypeptide) which results in a characteristic.
what are alleles?
versions of a gene.
why is the order of bases in each allele slightly different?
because each allele codes for different versions of the same characteristic.
how are alleles represented?
using letters.
how many alleles do most animals and plants have?
2 - one from each parent.
^ because we inherit one copy of each chromosome of a pair from our parents.
what is a locus?
the fixed position on a gene where an allele is found.
what is a genotype?
the alleles an organism has.
what is a phenotype?
the characteristics the alleles produce.
what does homozygous mean?
if an organism carries 2 copies of the same allele.
what does heterozygous mean?
if an organism carries 2 different alleles.
what is a dominant allele?
an allele whose characteristic appears in the phenotype even when there’s only 1 copy.
how are dominant alleles shown?
by a capital letter.
what is a recessive allele?
an allele whose characteristics only appear in the phenotype if 2 copies are present.
how are recessive alleles shown?
by a lower case letter.
what are codominant alleles?
when some alleles are both expressed in the phenotype because neither one is recessive.
