Bio 1080 Chapter 14

Front 1

monohybrid cross

Back 1

a cross to study only 2 variations of a single trait

Front 2

F1 generation

Back 2

1st filial generation: offspring produced by crossing 2 true-breeding strains (from the P generation)

Front 3

all F1 plants resembled only _______ parent

Back 3

one

Front 4

F2 generation

Back 4

2nd filial generation: offspring resulting from the self-fertilization of F1 plants- although the F1 generation only expressed the dominant trait, the recessive trait reappeared among some F2 individuals

Front 5

F1 generation were ___________ of the gene for the recessive trait

Back 5

carriers

Front 6

phenotypic dominant to recessive ratio for F2 plants

Back 6

3:1

Front 7

genetic ratio for F2 plants

Back 7

1 true breeding dominant: 2 not true breeding dominant: 1 true breeding recessive

Front 8

gene

Back 8

inforamtion for a trait passed from parent to offspring

Front 9

alleles

Back 9

alternate forms of a gene

Front 10

homozygous

Back 10

having two of the same allele

Front 11

heterozygous

Back 11

having 2 different alleles

Front 12

genotype

Back 12

total set of alleles of an individual- 1 copy obtained form each parent

Front 13

pheotype

Back 13

outward appearance of an individual

Front 14

principle of segregation

Back 14

two alleles for a gene are segregate during gamete formation and are rejoined at random, one from each parent, during fertilization- physical basis for allele segregation is the behavior of chromosomes during meiosis

Front 15

testcross

Back 15

a cross used to determine the genotype of an individual with dominant phenotype

Front 16

testcross procedure

Back 16

cross the individual with unknown genotype with a homozygous recessive- the phenotypic ratios among offspring are different, depending on the genotype of the unknown parent (dominant homozygous: all purple. heterozygous: 1/2 white 1/2 purple)

Front 17

dihybrid cross

Back 17

examination of 2 separate traits in a single cross

Front 18

dihybrid cross RrYy x RrYy ratio

Back 18

9 dominant for both

3 dominant for R only

3 dominant for Y only

1 recessive for both

Front 19

law of independent assortment

Back 19

in a dihybrid cross, the alleles of each gene assort independently- caused by the independent alignment of different homologous chromosome pairs during metaphase

Front 20

rule of addition (probability)

Back 20

"OR" -probability of 2 mutually exclusive events occurring simultaneously is the sum of their individual probabilities

Front 21

rule of multiplication (probability)

Back 21

"AND" -the probability of two independent events occurring simultaneously is the PRODUCT of their individual probabilities

Front 22

incomplete dominance

Back 22

heterozygote is intermediate in phenotype between the 2 homozygotes- ex. red flowers x white flowers = pink flowers

Front 23

codominance

Back 23

heterozygote shows some aspect of the phenotypes of both homozygotes- ex. type AB blood

Front 24

multiple alleles

Back 24

may be more than 2 alleles for a gene in a population (ABO bloodtype in humans, 3 alleles)

Front 25

I bloodtype gene alleles

Back 25

IA, IB, and i

Front 26

codominance of bloodtype

Back 26

IA and IB are dominant to i but codominant to each other

Front 27

pleiotropy

Back 27

refers to an allele which has more than one effect on the phenotype- pleiotropic effects are difficult to predict, b/c a gene that affects one trait often performs other, unknown funtions (ex cystic fibrosis, sickle cell anemia)

Front 28

polygenic inheritance

Back 28

occurs when multiple genes are involved in controlling the phenotype of a trait- the phenotype is an accumulation of contributions by multiple genes (human height, skin color)

Front 29

these traits show continuous variation and are referred to as quantitative traits

Back 29

polygenic inheritance (human height, skin color)

Front 30

environmental influence

Back 30

the expression of some genes can be influenced by the environment (coat color in himalayan rabbits and siamese cats)

Front 31

epistasis

Back 31

when a gene at one locus alters the phenotypic expression of a gene at a second locus (ex. labs: B for black and b for brown, another gene has C for color and c for no color)

Front 32

carriers (of recessive disorders)

Back 32

heterozygous individuals who carry the recessive allele but are phenotypically normal

Front 33

pedigree analysis

Back 33

a technique used to track inheritance patterns in families- dominant trait appears in every generation

Front 34

amniocentesis

Back 34

collects fetal cells from the amniotic fluid for examination (starting 14-16th week)

Front 35

chorionic villi sampling (CVS)

Back 35

collects cells from the placenta for examination (by 8-10th week)

Front 36

the principle of segregation

Back 36

the two alleles for a heritable character separate (segregate) during gamete formation and end up in different gametes