chapter 25 Flashcards
allele
different versions of genes for specific trait
phenotype
group of characteristics that can be observed/tested for
genotype
genetic makeup
meiosis I
first division
distributes 2 members of each chromosome pair into separate cells
meiosis II
second division
separates strands of duplicated chromosomes and distributes strands into individual gametes
examples of sex-linked traits
hemophilia, certain types of baldness, red-green color blindness
codominance
dominant alleles expressed together
why are mitochondrial inheritance disorders only passed from mother to offspring?
almost all zygote cytoplasm comes from ovum
mitochondria of sperm are contained in midshaft, not head
talipes
clubfoot
congenital (distortion during fetal growth)
polydactyly
6 fingers
congenital and hereditary
what does rubella (german measles) result in?
infection during first 3-4 months of pregnancy can cause 40% chance of cataracts, hearing loss, brain/heart defects
myelomeningocele
spinal cord and meninges protrude through spina bifida
causes spinal cord to end and affects function below
meningocele
meninges protrude through spina bifida
what does folic acid do during pregnancy?
intake of folic acid (a vitamin B) reduces risk of all CNS fetal defects
klinefelter syndrome
XXY
union of normal gamete with gamete containing extra X chromosome
Turner syndrome
XO
union of X gamete with gamete lacking sex chromosome
generally results in miscarriage, but girls can be born with web-like neck/cardiovascular issues
Huntington disease
dominant
progressive degenerative disorder
no cure, does not present until age 40
Marfan syndrome
dominant
connective tissue disorder
tall, thin, heart defects
phenylketonuria
recessive
lack of enzyme preventing metabolism of common amino acid phenylalanine
if untreated, causes severe mental issues before 2 years old
can be treated with special formula and low protein diet
cystic fibrosis
recessive - most common in white populations
causes thickened secretions of bronchi, intestines, pancreatic ducts
can be treated with enzymes and pulmonary exercises
fragile X syndrome
recessive
most common cause of mental delay in males and fairly high in females
fragile site on X chromosome arm
osteogenesis imperfecta
“brittle bone disease”
inherited
many fractures can occur before or during birth
neurogibromatosis
inherited
causes multiple masses (often on stalks called pedunculated) to grow along nerves
what are the 3 tests done during the first trimester
- nuchal transparency test (looking for nucha)
- pregnancy associated plasma protein A test
- human chorionic gonadotropin test
nucha
excess of fluid on back of fetal neck
what are the 3 tests done during the second trimester
- alpha-fetoprotein screening
- estriol test (hormone from placenta)
- inhibin test (hormone from placenta)
what are the 2 ways to obtain fetal cells to test for genetic diseases
- amniocentesis (14-16 weeks, <0.1% spontaneous abortion)
- chorionic villus sampling (8-10 weeks, 1% spontaneous abortion)
karyotype
produced by growing cells obtained from amniocentesis or CVS in medium arresting in metaphase
allows to look for genetic variations with certain stains
genetic diseases that can be prevented/controlled with diet
- maple syrup urine disease (high thiamine and low amino acids)
- wilson disease (dietary and drug therapies to prevent copper accumulation)
- phenylketonuria (special formula and low protein)
