7. Genetics Flashcards
what is a phenotype
expression of a trait
what is a genotype
genetic makeup of a trait
what does homozygous mean
individual has 2 recessive or 2 dominant alleles
what does heterozygous mean
individual has one recessive and one dominant allele
what does complete dominance mean
for any one trait a diploid individual will have 2 chromosomes that code for a specific trait
where are the corresponding genes located for complete dominance chromosomes
located at the same positions on the respective chromsomes
what is gene contribution like for complete dominance
each gene contributes an allele to the genotype and only one allele is expressed
what is mendels first law
alleles segregate independently of each other when forming gametes
any gamete is equally likely to possess any allele and the phenotype is the expression of the dominant allele
when is incomplete dominance seen
when heterozygous individual exhibits a phenotype that is intermediate between the homozygous counterparts
when does codominance occur
when heterozygous exhibits both phenotypes
what are sex linked genes
when gene is found on a sex chromosomes
in most cases does the X or Y chromosome carry the allele for the sex-linked trait
X
what happens as a result of the X chromsomes often carrying the allele for the sex-linked trait
the allele that is carried on the x chromosomes of males are expressed whether it is recessive or dominant
what happens in somatic cells when the X chromosome has a sex linked allele
one of the X chromosomes will condense and the genes will become inactive and form a Barr body
even though genotype determines phenotype what else must be considered
the environment will still influence the genotype and phenotype relationship
