chapter 25

Question 1

allele

Answer 1

different versions of genes for specific trait

Question 2

phenotype

Answer 2

group of characteristics that can be observed/tested for

Question 3

genotype

Answer 3

genetic makeup

Question 4

meiosis I

Answer 4

first division
distributes 2 members of each chromosome pair into separate cells

Question 5

meiosis II

Answer 5

second division
separates strands of duplicated chromosomes and distributes strands into individual gametes

Question 6

examples of sex-linked traits

Answer 6

hemophilia, certain types of baldness, red-green color blindness

Question 7

codominance

Answer 7

dominant alleles expressed together

Question 8

why are mitochondrial inheritance disorders only passed from mother to offspring?

Answer 8

almost all zygote cytoplasm comes from ovum
mitochondria of sperm are contained in midshaft, not head

Question 9

talipes

Answer 9

clubfoot
congenital (distortion during fetal growth)

Question 10

polydactyly

Answer 10

6 fingers
congenital and hereditary

Question 11

what does rubella (german measles) result in?

Answer 11

infection during first 3-4 months of pregnancy can cause 40% chance of cataracts, hearing loss, brain/heart defects

Question 12

myelomeningocele

Answer 12

spinal cord and meninges protrude through spina bifida
causes spinal cord to end and affects function below

Question 13

meningocele

Answer 13

meninges protrude through spina bifida

Question 14

what does folic acid do during pregnancy?

Answer 14

intake of folic acid (a vitamin B) reduces risk of all CNS fetal defects

Question 15

klinefelter syndrome

Answer 15

XXY
union of normal gamete with gamete containing extra X chromosome

Question 16

Turner syndrome

Answer 16

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

Question 17

Huntington disease

Answer 17

dominant
progressive degenerative disorder
no cure, does not present until age 40

Question 18

Marfan syndrome

Answer 18

dominant
connective tissue disorder
tall, thin, heart defects

Question 19

phenylketonuria

Answer 19

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

Question 20

cystic fibrosis

Answer 20

recessive - most common in white populations
causes thickened secretions of bronchi, intestines, pancreatic ducts
can be treated with enzymes and pulmonary exercises

Question 21

fragile X syndrome

Answer 21

recessive
most common cause of mental delay in males and fairly high in females
fragile site on X chromosome arm

Question 22

osteogenesis imperfecta

Answer 22

“brittle bone disease”
inherited
many fractures can occur before or during birth

Question 23

neurogibromatosis

Answer 23

inherited
causes multiple masses (often on stalks called pedunculated) to grow along nerves

Question 24

what are the 3 tests done during the first trimester

Answer 24

1. nuchal transparency test (looking for nucha)
2. pregnancy associated plasma protein A test
3. human chorionic gonadotropin test

Question 25

nucha

Answer 25

excess of fluid on back of fetal neck

Question 26

what are the 3 tests done during the second trimester

Answer 26

1. alpha-fetoprotein screening
2. estriol test (hormone from placenta)
3. inhibin test (hormone from placenta)

Question 27

what are the 2 ways to obtain fetal cells to test for genetic diseases

Answer 27

1. amniocentesis (14-16 weeks, <0.1% spontaneous abortion)
2. chorionic villus sampling (8-10 weeks, 1% spontaneous abortion)

Question 28

karyotype

Answer 28

produced by growing cells obtained from amniocentesis or CVS in medium arresting in metaphase
allows to look for genetic variations with certain stains

Question 29

genetic diseases that can be prevented/controlled with diet

Answer 29

1. maple syrup urine disease (high thiamine and low amino acids)
2. wilson disease (dietary and drug therapies to prevent copper accumulation)
3. phenylketonuria (special formula and low protein)