7.1 inheritance Flashcards
gene
sequence of bases on a molecule which code for a polypeptide, resulting in a characteristic
allele
different forms of genes
genotype
genetic composition of an organism
phenotype
characteristics of an organism which are often visible, resulting from the genotype and the environment
dominant allele
always expressed in the phenotype
recessive allele
only expressed in the phenotype when homozygous
codominant alleles
alleles which are both expressed in the phenotype if both are present
sex-linkage gene
a gene that is carried on the X or Y chromosome
locus
fixed position of a gene on a chromosome
hetrozygous
two different alleles for a particular gene
homozygous
having two of the same allele for a particular gene
carrier
a person carrying an allele which is not expressed but can be passed onto offspring
monohybrid inheritance
inheritance of a characteristic controlled by a single gene
dihybrid inheritance
inheritance of two pairs of alleles
what does a monohybrid cross show you
the likelihood of different alleles of that gene being inherited by the offspring of certain parents
what does a dihybrid cross show you
how two different genes are inherited at the same time
what is a sex linked gene
a gene with a locus on sex chromosomes only X/Y
why are males more likely to express recessive x-linked alleles
if males are XY, they only have to inherit 1 recessive allele, females as XX have to inherit 2
what is autosomal linkage
when two or more genes are on the same autosomal chromosome, they will be inherited together
how does crossing over affects autosomal linkage
crossing over can separate linked genes, so fewer autosomal linked gametes are inherited
what is epistasis
interaction of non-linked genes where one masks the expression of the other
when is chi-squared used
when determining if observed results are significantly different from expected results, when data is categorical
what causes observed phenotypes to be different to expected frequencies
fertilisation is random
autosomal linkage/ epistasis/ sex-linked
small sample size
lethal genotype
