Mapping and Linkage

Question 1

what was the big discovery with the immunoglobulin experiment

Answer 1

found that the patient did not have IgA, IgM or IgG

Question 2

describe autosomal dominant inheritance pedigree

Answer 2

• vertical pattern pedigree
• equally affects males and females
• only need 1 infected parent to receive
• 50% chance of receiving from infected parent

Question 3

describe autosomal recessive inheritance pedigree

Answer 3

• horizontal pattern
• equally affects males and females
• both parents must be at least carriers
• offspring of 2 carriers = 25% affect, 25% not affected, 50% carriers
• 2/3 of offspring of clinically normal offspring are carriers
• the rarer the trait, the more likely there was consanguineous (in breeding)

Question 4

describe the pedigree for Y chromosome inheritance

Answer 4

• only males affected
• only male to male infection
  ex: DAZ locus that causes azoospermia

Question 5

describe the pedigree for mitochondria inheritance

Answer 5

• only maternal transmission
• can affect males and females
• mitochondria comes from the mother
  ex: Leber’s disease

Question 6

describe the pedigree for a X-linked inheritance

Answer 6

-no male to male transmission
-all daughters of affected males are heterozygous
-unaffected fathers cannot pass onto children
-whether deemed “dominant” or “recessive” depends on the examination
-

Question 7

what stage does crossing over occur

Answer 7

Meiosis I

Question 8

what kind of markers can be used to make a gene map

Answer 8

1. phenotypes
2. a physical different/genetic alteration (electrophoretic)
3. SNPs
4. unique DNA differences

Question 9

what is an LOD score

Answer 9

the likely hood that two markers are linked at a particular distance
>3 = linkage for mendalian train
>2 = linkage for multigene trait

Question 10

what can you quantify in quantitative inheritance

Answer 10

• phenotypes can be measured in units
• traits are continuous
• genotypes have large variance
• environmental influences are strong
• difference between genotypes usually less than the variance of the trait within a genotype
• usually have multiple loci each contributing a small percentage of trait

Question 11

what is cytogenetic analysis

Answer 11

FISH- looking for binding of DNA-marker probe directly to chromosome
-look for association of probe with chromosomal aberrations