Chapter 12

Question 1

Gregor Mendel

Answer 1

Austrian monk
mathematician (1860s)
studied pea plants
“factors”
F1 and F2 generations

Question 2

Factors

Answer 2

genes
homologous chromosomes

Question 3

Locus

Answer 3

location of gene

Question 4

Allele

Answer 4

alternate form of gene
character (color) and trait (pur vs white)

Question 5

True-breeding

Answer 5

bred trait for generations (multiple generations of purple and white)
used for hybridization
parental generation

Question 6

F1

Answer 6

First filial generation
offspring of hybridization

Question 7

F2

Answer 7

Second filial generation
offspring of hybrids
different traits often reappear

Question 8

Mendel’s model of inheritance

Answer 8

Alternative forms of genes exist (alleles represented by letters)
Organisms inherit 2 alleles (one from each parent)
Dominant and recessive alleles

Question 9

Dominant alleles

Answer 9

represented by capital letter
if present masks recessive
not “better” or “stronger”

Question 10

Recessive alleles

Answer 10

will be masked by dominant
unless both alleles are recessive
may be carried into generation

Question 11

Gametogenesis

Answer 11

Separation of alleles

Question 12

Zygosity

Answer 12

degree of allelic similarity of Homo chromos
homo or hetero zygous

Question 13

Homozygous

Answer 13

both alleles the same
dominant or recessive
AA, aa

Question 14

Heterozygous

Answer 14

both alleles different
Aa (carrier)

Question 15

Phenotype

Answer 15

visible appearance

Question 16

Genotype

Answer 16

Actual alleles for trait

Question 17

Monohybrid cross

Answer 17

one trait inheritance
follow sperm and egg
all combinations
complete dominance
punnett squares

Question 18

Test cross

Answer 18

when you don’t know if PP or Pp
b/c both purple phenotype
perform test cross with pp

Question 19

Dihybrid cross

Answer 19

two trait inheritance follow sperm and egg
independent assortment
all combination of gametes

Question 20

Probability of events

Answer 20

ranges from 0 ->1
independent events

Question 21

multiplication rule

Answer 21

event 1 and event 2
ex: P sperm and p egg
1/2 x 1/2 = 1/4

Question 22

Addition rule

Answer 22

event 1 or event 2
ex: P sperm; p egg
OR p sperm; P egg
1/4 +1/4 = 1/2

Question 23

Law of segregation

Answer 23

mendel had not knowledge of chromosomes
1 trait must be masked and carried into F2
each plant has 2 factors
1 factor dominates other
factors separate during gametogenesis.

Question 24

Law of independent assortment

Answer 24

mendel had no knowledge of meiosis
distinct traits do not affect each other
dependent and independent assortment

Question 25

Dependent assortment

Answer 25

both traits dominant or recessive
prediction -> 3:1

Question 26

Independent assortment

Answer 26

all gamete combinations tracked
prediction -> 9:3:3:1
during metaphase, 2nd source of genetic variation
color does not affect smoothness

Question 27

Pedigree analysis

Answer 27

chart of family history
emphasis on one trait
squares (M) circles (F)
shaded (affected)
infer genotypes from previous generations and current offspring

Question 28

Autosomal dominant

Answer 28

genotypes of “WW” or “Ww”
rarer (no widows peak;ww)

Question 29

Autosomal recessive

Answer 29

more common (cannot taste PTC)
must inherit “tt”

Question 30

Autosomal recessive disorders

Answer 30

Tay-sachs disease: lack certain enzyme build up in lysosome
Cystic Fibrosis: affects Cl- channels creates thick mucus
Albinism
Sickle cell disease: sickle cell trait ; heterozygote; malaria resistance

Question 31

Autosomal dominant

Answer 31

Osteogenesis imperfecta: weakened/brittle bones, collagen synthesis
Huntington disease: neurological disorder, degeneration of brain cells

Question 32

Incomplete dominance

Answer 32

Intermediate phenotype
3 phenotypes possible
ex: red + white = pink

Question 33

Codominance

Answer 33

Heterozygote
alleles equally expressed
AB blood type

Question 34

Multiple allels

Answer 34

several allelic forms exist, you can only have 2

Question 35

Epistatic interactions

Answer 35

interaction between gene factors, one gene overrides another