Chapter 14: Mendel

Question 1

character

Answer 1

heritable feature that varies among individuals

Question 2

trait

Answer 2

variant for a character

Question 3

true breeding

Answer 3

offspring have the same phenotype

Question 4

hybridization

Answer 4

crossing of two true-breeding varieties

Question 5

P generation

Answer 5

true breeding parent generation

Question 6

F1 generation

Answer 6

hybrid offspring of P generation

Question 7

F2 generation

Answer 7

offspring of F1 hybrids

Question 8

Mendel’s Model

Answer 8

1. alleles cause variation in characters
2. two copies of a gene, one from each parent, are inherited for each character
3. dominant allele determines phenotype over recessive allele
4. law of segregation

Question 9

allele

Answer 9

alternative versions of a gene

Question 10

law of segregation

Answer 10

two alleles segregate during gamete formation so each gamete has only one of two alleles

Question 11

homozygous

Answer 11

identical alleles for a gene

Question 12

heterozygous

Answer 12

two different alleles for a gene

Question 13

phenotype

Answer 13

appearance

Question 14

genotype

Answer 14

genetic makeup

Question 15

testcross

Answer 15

cross of homozygous organism with organism of unknown genotype

Question 16

monohybrids

Answer 16

heterozygous for one character

Question 17

dihybrid

Answer 17

heterozygous for two character

Question 18

law of independent assortment

Answer 18

each pair of alleles segregates independently of each other pair of alleles during gamete formation

Question 19

independent events

Answer 19

unaffected by other events

Question 20

multiplication rule

Answer 20

calculate the probability that 2+ more independent events will occur together by multiplying individual probabilities

Question 21

mutually exclusive events

Answer 21

events that cannot occur together

Question 22

addition rule

Answer 22

probability that any one of 2+ mutually events will occur is calculated by adding individual probabilities

Question 23

complete dominance

Answer 23

dominant allele completely masks recessive allele

Question 24

incomplete dominance

Answer 24

neither allele is completely dominant

Question 25

codominance

Answer 25

each allele affects phenotype in separate, distinguishable ways

Question 26

Tay-Sachs disease

Answer 26

inherited disorder where brain cells cannot metabolize certain lipids, causing seizures, blindness, death.

Question 27

pleiotropy

Answer 27

one gene has multiple phenotypic effects

Question 28

epistasis

Answer 28

phenotypic expression of a gene at one locus alters that of a gene at a second locus

Question 29

quantitative characters

Answer 29

vary in population in gradations along a continuum

Question 30

polygenic inheritance

Answer 30

2+ genes affect one character

Question 31

norm of reaction

Answer 31

phenotypic range for a genotype

Question 32

multifactorial

Answer 32

many factors, environmental + genetic, affect phenotype

Question 33

pedigree

Answer 33

family tree describing traits of parents + children across generations

Question 34

carriers

Answer 34

heterozygotes that have recessive gene but are phenotypically normal

Question 35

cystic fibrosis

Answer 35

genetic disease with defective chloride transport channels in plasma membranes. causes thicker mucus. recessive

Question 36

sickle-cell disease

Answer 36

substitution of valine for glutamic acid in hemoglobin causing blood cells to have sickle shape. recessive

Question 37

huntington’s disease

Answer 37

dominant genetic disorder. degenerative disease of nervous system that only appears at 35-45 years old.

Question 38

amniocentesis

Answer 38

physician inserts needle and extracts 10 mL amniotic fluid in 14th-16th week of pregnancy.

Question 39

chorionic villus sampling

Answer 39

physician inserts narrow tube through cervix into uterus and suctions out sample of tissue from placenta

Question 40

phenylketonuria (PKU)

Answer 40

cannot properly digest amino acid phenylalanine, which accumulates to toxic levels in the blood -> retard