Test 4- Altered Mendelian Ratios, Chromosome Structure, & Linkage

Question 1

Multiple alleles

Answer 1

One wt and multiple mutants

• ABO Blood groups
• drosophila eye color

Question 2

Incomplete dominance

Answer 2

Intermediate phenotype

-horse coat

Question 3

Codominance

Answer 3

Exhibits phenotype of both parents
-blood groups
-cattle coloring
both alleles expressed

Question 4

Essential genes

Answer 4

Necessary for viability
Result in death
Dominant or recessive
2:1 phenotypic ratio

Question 5

Penetrance

Answer 5

Frequency that gene manifests its phenotype in pop

Question 6

Complete penetrance

Answer 6

Identical genotypes gives all expected phenotypes

Question 7

Incomplete penetrance

Answer 7

Identical known genotypes don’t all give expected phenotype

Question 8

Expressivity

Answer 8

Degree to which penetrant gene influences phenotype

Question 9

Constant expressivity

Answer 9

Identical genotypes yield expected phenotypes

Question 10

Variable expressivity

Answer 10

Identical genotypes yield range of phenotypes

Question 11

Environmental influences

Answer 11

Age of onset
Sex
Temperature
Chemicals

Question 12

Age of onset

Answer 12

Early v. Young

Dmd 2-5 years
Huntingtons 40+ years

Question 13

Sex

Answer 13

Sex limited traits

Sex influenced traits

Question 14

Sex limited traits

Answer 14

Autosomal genes affects trait in one sex

Milk production

Question 15

Sex influenced traits

Answer 15

Frequency of occurrence varies between genders

Male pattern baldness- Dom. in males; Rec. in females

Question 16

Temperature

Answer 16

Temp affects enzyme function
Himalayan rabbits
Gender of sea turtles

Question 17

Environmental chemicals

Answer 17

PKU- phe build up

Phenocopies-nonhereditary phenotype induced by environmental chems

Question 18

Modified Mendelian ratios

Answer 18

2+ genes affecting same phenotype

-chicken comb

Question 19

Epistasis

Answer 19

Masking or modification o one genes expression by another

Question 20

Epistatic gene

Answer 20

Masking gene

Question 21

Hypostatic gene

Answer 21

Masked gene

Question 22

Recessive epistasis

Answer 22

9:3:4
1 recessive gene overpowers 2nd gene regardless of its genotype
Lab fur

Question 23

Dominant epistasis

Answer 23

12:3:1
1 Dom gene overrules other gene regardless of genotype
Summer squash color

Question 24

duplicate gene epistasis

Answer 24

gene at one locus produces phenotype identical to gene at another locus

rec: 9:7 phenotypic
dom: 15:1 phenotypic

Question 25

maternal effect

Answer 25

phenotype due to maternal genotype important in developmental processes -snail shell coiling

Question 26

x2

Answer 26

d2/e | x2>chart value=>linked

Question 27

mapping distances

Answer 27

sco+dco/total*100%=mu

Question 28

interference

Answer 28

1-coefficient of coincidence

Question 29

coefficient of coincidence

Answer 29

obs dco/exp dco

Question 30

observed dco freq

Answer 30

dco/total

Question 31

expected dco freq

Answer 31

mu/100*mu/100

Question 32

chromosomal mutations

Answer 32

deletion duplication inversion translocation

Question 33

drosophila polytene chromosomes

Answer 33

chromatid bundles produced by endoreduplication homologous chromatids tightly paired joined at chromocenter

Question 34

deletions

Answer 34

loss of part of chromosome due to DNA break cant revert loss of centomere=acentric chromosome

Question 35

human deletions

Answer 35

cri-du-chat: deletion from p arm of chromo 5 prader-willi: deletion from q arm of chromo 15 1p36: deletion from p arm of chromo 1

Question 36

duplications

Answer 36

tandem reverse tandem terminal tandem -alpha/beta cluster for human hemoglobin

Question 37

paracentric inversions

Answer 37

excision and reintegration of chromosomal material in reverse orientation w/o affecting centromere

Question 38

pericentric inversion

Answer 38

material in reverse orientation w/ affecting centromere

Question 39

translocation

Answer 39

segment moved to new location - nonreciprocal intrachromosomal - nonreciprocal interchromosomal - reciprocal interchromosomal - -alternate, adjacent I & 2 segregation

Question 40

chromosomal mutations in humans

Answer 40

usually due to translocations -CML: 9&22-philadelphia chromosome -Burkitt's Lymphoma: 8&14 leads to tumors

Question 41

position effect

Answer 41

change in gene expression due to change in location inversions and translocations move to heterochromatic region can suppress gene (eyes of drosophila)

Question 42

fragile X syndrome

Answer 42

CGG repeats at q of X

Question 43

aneuploidy

Answer 43

variation from normal # of chromosome complement | typically not tolerated by animals, but exhibited by plants

Question 44

human aneuploidy

Answer 44

trisomy 21: downs syndrome Robertsonian translocation: long arm of chromo 21 translocates so offspring gets 3 copies trisomy 13: patau syndrome: sleft palate, polydactyly, mental impairment, cardiac anomalies, death by 3yo trisomy 18: edwards syndrome: 80% female, severe organ system malformations, clenched fists, death by 6mos