chapter 23 - characteristics of offspring

Question 1

symbols and colours in pedigrees

Answer 1

• S: male = square, female = circle

- C: represents genotype a or phenotypes of the individual

Question 2

what are the uses of pedigrees

Answer 2

• figuring out in,noon genotypes
• determining which parent a child inherited an allele from
• identify when a particular allele entered a family lineage

Question 3

how to identify an autosomal recessive trait

Answer 3

• often skips generations
• almost equal number of affected males and females
• trait often found when incestuous mating occurs
• both parents affected = all children affected (bb x bb)
• most children have unaffected parents (Bb x Bb)

Question 4

how to identify an autosomal dominant trait

Answer 4

• generally doesn’t skip generations

- equal number of males and females

Question 5

how to identify an x-linked recessive trait

Answer 5

• most affected individuals are male
• skips generations
• affected female = affected female and affected / carrier mother
• affected mother = affected son

Question 6

how to identify an x-linked dominant trait

Answer 6

• more affected males
• does not skip generations
• affected mothers = affected sons
• affected female = affected mother or father

Question 7

what is a pedigree

Answer 7

• represents lineage of a family, shows who had children with who and what the genotype a of the family members are
• show how individuals are related and how alleles are passed from one generation to the next

Question 8

examples of traits

Answer 8

• A,R: phenylketonuria (PKU), thalassaemia, cystic fibrosis, sickle cell disease
• A,D: huntingtons, achondroplasia
• X,R: haemophilia, colourblindness, duchene muscular dystrophy
• X,D: fragile X syndrome