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

Genetics > Test 4- Altered Mendelian Ratios, Chromosome Structure, & Linkage > Flashcards

Flashcards in Test 4- Altered Mendelian Ratios, Chromosome Structure, & Linkage Deck (44):
1

Multiple alleles

One wt and multiple mutants
-ABO Blood groups
-drosophila eye color

2

Incomplete dominance

Intermediate phenotype
-horse coat

3

Codominance

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

4

Essential genes

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

5

Penetrance

Frequency that gene manifests its phenotype in pop

6

Complete penetrance

Identical genotypes gives all expected phenotypes

7

Incomplete penetrance

Identical known genotypes don't all give expected phenotype

8

Expressivity

Degree to which penetrant gene influences phenotype

9

Constant expressivity

Identical genotypes yield expected phenotypes

10

Variable expressivity

Identical genotypes yield range of phenotypes

11

Environmental influences

Age of onset
Sex
Temperature
Chemicals

12

Age of onset

Early v. Young

Dmd 2-5 years
Huntingtons 40+ years

13

Sex

Sex limited traits
Sex influenced traits

14

Sex limited traits

Autosomal genes affects trait in one sex
Milk production

15

Sex influenced traits

Frequency of occurrence varies between genders
Male pattern baldness- Dom. in males; Rec. in females

16

Temperature

Temp affects enzyme function
Himalayan rabbits
Gender of sea turtles

17

Environmental chemicals

PKU- phe build up
Phenocopies-nonhereditary phenotype induced by environmental chems

18

Modified Mendelian ratios

2+ genes affecting same phenotype
-chicken comb

19

Epistasis

Masking or modification o one genes expression by another

20

Epistatic gene

Masking gene

21

Hypostatic gene

Masked gene

22

Recessive epistasis

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

23

Dominant epistasis

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

24

duplicate gene epistasis

gene at one locus produces phenotype identical to gene at another locus
rec: 9:7 phenotypic
dom: 15:1 phenotypic

25

maternal effect

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

26

x2

d2/e
x2>chart value=>linked

27

mapping distances

sco+dco/total*100%=mu

28

interference

1-coefficient of coincidence

29

coefficient of coincidence

obs dco/exp dco

30

observed dco freq

dco/total

31

expected dco freq

mu/100*mu/100

32

chromosomal mutations

deletion
duplication
inversion
translocation

33

drosophila polytene chromosomes

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

34

deletions

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

35

human deletions

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

36

duplications

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

37

paracentric inversions

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

38

pericentric inversion

material in reverse orientation w/ affecting centromere

39

translocation

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

40

chromosomal mutations in humans

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

41

position effect

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

42

fragile X syndrome

CGG repeats at q of X

43

aneuploidy

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

44

human aneuploidy

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