inheritance patters

Question 1

homogametic

Answer 1

XX, ZZ

Question 1

heterogametic

Answer 1

XY, ZW (determines gender)

Question 2

how many alleles does an animals have/gene

Answer 2

two

Question 3

what is an allele

Answer 3

a version of a gene

Question 4

why is an example of an ethical mate choice for a dominant mutation in manx

Answer 4

-in manx cats to breed mm X Mm because you will result in 50% Mn (show quality) and 50% mm (tails)
-same precent will be show quality in Mm X Mm except 1/4 will be MM and die, with 1/4 long tail

Question 5

breeding Oo X Oo ovaro in horses

Answer 5

-1 oo (solid)
-2 Oo (ovaro)
- OO (white, lethal, intestinal issues)

Question 6

what happens if you breed Pp X Pp Chinese crested dog

Answer 6

1/4 lethal 1/2 show quality 1/4 powder puff

Question 7

dominance higharchy

Answer 7

-discovering which of more then two genes are more dominant
-because sometimes have more then 2 alleles at a locus

Question 8

melanocytes

Answer 8

produce pigment for hair follicle

Question 9

what are the two melanin pigments

Answer 9

phaeomelanin and eumelanin

Question 10

phaeomelanin

Answer 10

-melanin pigment
-red, yellow, cream

Question 11

eumelanin

Answer 11

-melanin pigment
-black, brown, grey

Question 12

melanocortin receptor 1 gene MC1R ED

Answer 12

ED=eumelanin=black

Question 13

melanocortin receptor 1 gene MC1R e

Answer 13

e/e=phaeomelanin=red

Question 14

melanocortin receptor 1 gene MC1R E+

Answer 14

-“wild type”
-colour depends on other genes
-i.e. brown

Question 15

heterozygote phenotypes

Answer 15

-heterozygots are different from either homozygotes
-codominant (both phenotypes expressed together but observed separately)
-incomplete dominant (both phenotypes expresses as a blend appearance

Question 16

codominance in merle dogs

Answer 16

-MM= deaf, some microphthalmic (small eyes)
-Mm= merle, heterochromic irides, some black patches and some white
-mm= not merle

Question 17

SLC45A2 or MATP gene in horses (codominance)

Answer 17

-CC=chestnut
-Cc=palomino
-cc=cremello
-if horses are e/e at MC1R, so no black (eumelanin) will be present

Question 18

autosomal recessive generalizations

Answer 18

-most are enzyme deficiencies (inborn errors of metabolism)
-phenotype is generally consistent, exspecially within a family
-symptoms often severe
-consanguinity common (linebred)

Question 19

why are many diseases called autosomal recessive

Answer 19

-because neither parents looks affected
-however not always autosomal recessive because you cant see it (can have reduced penetrance or be “dimmed”)
-but recessive X recessive=100% recessive offspring
-but such breeding is often not possible

Question 20

symptoms for autosomal recessive (generlizations)

Answer 20

-often severe
-many such disorders are present at birth=congenital
-if untreated, they are often lethal

Question 21

autosomal recessive (generlizations) consanguinity

Answer 21

-offten disorders show up when linebred is lised

Question 22

implications of autosomal recessives

Answer 22

-cull the homozygote affected
-both parents are “obligate” carriers…cull?

Question 23

what are the statistics if you were to breed two autosomal recessive carriers

Answer 23

-1 AA: 2 Aa: 1aa
-1/3 of unaffected not carriers
-2/3 of unaffected are carriers
-because 2/3 unaffected are carriers its important to have access to a carrier direction kit

Question 24

carrier detection tests

Answer 24

-breeding test
-direct tests (biochemical, DNA test for mutation)
-indirect test (DNA linkage test)

Question 25

carrier detection breeder tests

Answer 25

-mate a sire of interest to either affected dams of heterozygous carrier dams and see if any affected offspring are born
-if so sire is a carrier

Question 26

spider syndrome in sheep

Answer 26

-mate with carriers
-Ss ewes (s/s do not survive to breeding age)
-16 off spring all ok=99% chance sire is S/S
-if S/s X S/s
-1/4 of lambs will have spider syndrome

Question 27

testing if a polled sire carries horns

Answer 27

-mate sire to horned cows (homozygous p/p)
-polled in cattle is dominant to horned
-7 offspring have no horns= 99% chance sire PP
-(1/2)^7=0.0078

Question 28

how many times do you have to breed test something matted to aa (recessive)

Answer 28

7x

Question 29

ho many times do you need to mate to Aa (carrier)

Answer 29

16x

Question 30

mechanisms of a direct biochemical test

Answer 30

-measures specific range (level) of enzymes or protein
-Beta-mannosidosis or deficency of beta mannosidase
-homozygous normal=100% active (BB)
-heterozygote=50% active (Bb)
-affected=0% active (bb)
-gene dosage=affect
-not all samples give definitive results

Question 31

mechanisms of direct test DNA test for the mutation

Answer 31

-most tests now based on PCR
-method to amplify small amounts of DNA
-samples: hair roots, buccal swab, blood, semen

Question 32

indirect tests: DNA linkage test

Answer 32

-used when the causative gene is not known
-location of gene, or biochemical pathway, etc. is known
-less accurate then direct test i.e. depends on distance of marker to gene

Question 33

DNA linkage test mechanism

Answer 33

-use a marker “linked” to the causative gene
-DNA variation within an intron or other noncoding segment
-markers do not affect any phenotype so have “accumulated” in animals
-which allele segrates with the allele of interest is pedigree specific
-therefore must sample the family ot test for carriers

Question 34

when does recombination occur

Answer 34

during meiosis between homologous chromosomes

Question 35

why would a carrier detection test be used for a dominant disorder

Answer 35

-if dominant dis order is late onset, so genotype is know prior to breeding