genotype, phenotype and inheritance Flashcards
define genotype
the genetic make up of an individual
define phenotype
the observable characteristic determined by interaction of the genotype with the environment
define allele
a form of a gene
define homozygous
2 alleles of a gene the same
define heterozygous
2 alleles of a gene different
define hemizygous
only 1 allele of the gene on the x chromosome
males only
define what a dominant allele is
allele that determine the phenotype in a htz
define what a recessive allele is
non-dominant allele in a htz
what is co dominance? give an example
when both alleles of the gene are expressed creating an intermediate phenotype
blood group - A + B both dominant over O
when A + b alleles present both expressed to AB group, show co dominance
What is a male on family tree?
square
What is a female on family tree?
circle
What show a carrier on a family tree?
half shading
What shows an affected individual on a family tree?
full shading
What shows a deceased individual on a family tree?
line through circle/square
What is autosomal recessive inheritance? Give an example of a disease inherited in this manner
only hmz affected
htz carriers
cystic fibrosis
What is a autosomal dominant inheritance? Give an example of a disease inherited in this manner
htz affected
hmz state rare as often so severe is lethal
huntington’s
What is X-linked recessive inheritance? Give an example of a disease inherited in this manner.
hemizygous males and hmz females affected
increased frequency in males
htz females carriers
affected males cannot pass trait on to sons
What is X linked dominant inheritance? Give an example of a disease inherited in this manner.
hemizygous males and htz females affected
affected males can’t pass trait on tosons
example- rett’s syndrome
What is Y linked inheritance? Give an example of a disease inherited in this manner.
gene on y chromosome only
affects males only
example- Fabry disease
How is mitochondrial DNA inherited?
maternally
What does polygenic mean? Give a disease/phenotype inherited in this manner.
when multiple genes involved in generating a phenotype
albinism is recessively inherited, need recessive copies of the alleles of two genes
Genes on same chromosome are…
What does this mean for meiosis?
linked
no independent assortment at meiosis
genes on different chromosomes are…
not-linked
What is the recombination frequency dependent on?
distance between the genes
increased distance = increased crossing over liklihood
