Chapter11 Studying Flashcards
what is down syndrome caused by
trisomy of 21st chromosome
what fetal testing extracts small amounts of fluid from the amniotic sac
amniocentesis
what is an example of a human trait caused by multiple alleles
blood type
huntingtons disease
decline of mental treatment, symptoms dont show up until 30-50, affects 1 in 10,000 in US
what kind of disorder is huntingtons disease
autosomal dominant
genetic disorders caused by recessive alleles
cystic fibrosis, albinism, color blindness, hemophilia
genetic disorders caused by dominant alleles
huntingtons, achondroplasia
if a trait is sex linked, it is
controlled by genes on the x-chromosome
patterns of complex heredity
incomplete dominance, codominance, multiple alleles, epistasis, environmental influence, polygenic traits, dosage compensation
barr bodies
the randomly inactivated x in dosage compensation in female mammals
relationship between genotype, phenotype, and the environment
genotype codes for specific traits, phenotype is the outward expression of the code, environment determines the version of the outward expression you see
epistasis
when the regulatory gene hides the effect of another gene
in incomplete dominance what does not exist
a dominant allele
in codominance what is expressed
two dominant alleles at the same time
multiple alleles
traits controlled by more than two alleles
what do the letters in blood type mean
the type of antigen on the blood cell
what blood type is the universal receiver
type AB
what blood type is the universal donor
type O
rhesus factor
additional proteins on blood cells
what are the genotypes of chinchillas
C (black), c^ch (chinchilla), c^h (himalayan), c (albino)
dosage compensation
the x inactivation in every cell that controls the dosage of expressed traits
polygenic traits
a trait influenced or controlled by several genes
what are telomeres made of
repeating DNA sequences
what do telomeres do
protect DNA from shortening during meiosis and mitosis
when does nondisjunction normally occur
meiosis
what does nondisjunction cause
more or less chromosomes in a sex cell
does nondisjunction happen to all cells
no just sex cells
when do trisomy’s and monosomies occur
when a gamete formed from nondisjunction is fertilized
why is there a higher risk of down syndrome as the mother ages
telomeres get shorter and shorter
what fetal testings are there
amniocentesis, chronic villus sampling, fetal blood sampling, ultrasound
when is fetal testing used
when couples suspect that they are carriers of a genetic disorder during pregnancy
