mandelian inheritance

Question 1

monogenic inheritance

Answer 1

phenotype regulated by a single gene

Question 2

polygenic inheritance

Answer 2

phenotype regulated by many genes

Question 3

principle of segregation

Answer 3

during the formation of gametes, genes segregate randomly so that each gamete receives one or the other with equal likelihood

Question 4

principle of uniformity

Answer 4

when 2 genes responsible for a single phenotype, one gene is dominant and the other recessive

Question 5

testcross

Answer 5

determines if the dominant phenotype is homozygous or heterozygous

1. cross dominant individual with a homozygous recessive
   a. if all offspring are dominant they are homozygous dominant
   b. if half are dominant and half are recessive they are heterozygous

Question 6

principle of independent assortment

Answer 6

each pair of alleles segregates independently of other alleles during gamete formation

Question 7

why did Mendel succeed

Answer 7

• simple traites
• careful quantitative records
• designed hypotheses and tested them

Question 8

factors of autosomal recessive inheritance

Answer 8

• equal distribution of sexes
• tends to skip generations
• often appears as a result of parental consanguinity
  e. g. CF, albinism

Question 9

consanguinity

Answer 9

consanguinity increases frequency of genetic disease and mortality. the closer the degree of consanguinity, the greater the increase

Question 10

factors of autosomal dominant inheritance

Answer 10

• usually has at least one affected parent
• equal distribution of sexes
• transmitted by either sex
  e. g. huntington

Question 11

oculocutaneous albinism

Answer 11

mutant variant a cannot produce tyrosinase enzyme, normal a can produce tyrosine enzyme and synthesise tyrosine, thus melanin is produced. whilst a single copy of the enzyme is needed, heterozygous individuals are phenotypically normal, recessive homozygous individuals have albinism

Question 12

factors of x-linked recessive

Answer 12

• males usually affected
• no male to male transmission
• transmitted through female carriers
  e. g. haemophilia

Question 13

factors of x-linked dominant

Answer 13

• females more often affected
• no male to male transmission
• carrier female has a 50% chance to give to either sex offspring
• affects every generation
• females less affected due to x-inactivation
  e. g. protoporphyria

Question 14

x-inactivation

Answer 14

one x chromosome in each cell is randomly inactivated in females
this ensures females will produce x-linked gene products in similar quantities to males –> dosage compensation

Question 15

y-linked inheritance

Answer 15

hairy earlobes