exam 3 chapter 10 Flashcards
inheritance of characters by a single gene may deviate from simple Medelian patterns when…
- incompletely dominant or codominant
- multiple alleles
- pleiotropy
- epistasis
- nature and nurture
codominance
2 dominate alleles affect phenotype in separate distinguishable ways
incomplete dominance
a blend of phenotypes
multiple alleles
most genes have MORE THAN 2 allelic forms
example ABO blood I^A I^B i
Pleiotropy
a gene with multiple phenotypes example sickle cell and cystic fibrosis
epistasis (a)
two or more genes, a gene at one locus alters the phenotypic expression of another gene at a different locus
example:coat color of mice depends on two genes (one determining pigment and one determining if it will be deposited)
symptoms of cystic fibrosis
European decent
results in defective or absent chloride transport channels in plasma membranes
mucus buildup in internal organs and inadequate absorption of nutrients in the intestine
symptoms of sickle cell
African decent
oxygen content of an affected individual is low, the hemoglobin molecules aggregate and deform into this shape
clump and clog blood vessels to cause physical weakness, pain, organ damage, paralysis and even death
caused by the substitution of a single amino acid in the hemoglobin protein in red blood cells
epistasis (b)
two or more genes: polygenic inheritance
when two or more genes have an additive effect
example skin color in humans
nature (genotype) and nurture (environment)
some phenotypes depend on both the genotype and the environment
called MULTIFACTORAL because the factors collectively influence phenotype
example: heart disease, diabetes, obesity, cancer
AND hydrangea color depending on soil acidity
why are humans not good subjects for research
- generation time is too long
- only few offsprings are produced
- breeding is immoral
Pedigree
a family tree that describes the interrelationships of parent and children across generations
inheritance patterns of particular traits can be traced using these
name 3 recessively inherited traits
- albinism
- cystic fibrosis
- sickle cell disease
albinism
recessive condition characterized by lack of pigmentation in hair
carrier
heterozygous individuals that carry the recessive allele but are phenotypically normal
some genetic anomalies are cause by ______ alleles
dominant
_______ alleles rarely cause a lethal disease, most of the __________ are mild and not life threatening
dominate, abnormalities
achondroplasia
form of dwarfism caused by a rare dominant allele
hexadactyly
another anomaly cause by a dominate allele where you have 6 fingers or toes
chromosomal alterations often lead to ______ or cause a variety of ________ disorders
miscarriages, developmental
nondisjunction
pairs of homologous chromosomes do not separate normally during meiosis
one gamete receives two off the same type of chromosomes and another game receives none
leads to ANEUPLOIDY
aneuploidy
results from the fertilization of games in which nondisjunction occurred
may result in a trisomic or monosomic zygote
trisomic zygote
3 copies of a specific chromosome
monosomic zygote
one copy of a particular zygote
