Non-Mendelian Genetics: Non-Mendelian Genetics and Heredity

Question 1

Codominance

Answer 1

two dominant alleles are expressed at the same time

Question 2

Incomplete Dominance

Answer 2

no allele is completely dominant. BLENDING of phenotypes occurs to make a 3rd phenotype.

–> Only assume heterozygous genotype represents blending if told so. Otherwise, always assume the heterozygous genotype shows for the same dominant phenotype as homozygous dominant.

Question 3

Sex-linked Traits

Answer 3

traits found on a sex chromosome (X or Y), usually refers to X traits (because only males have Y)

Question 4

Sex-linked Traits

Relationships between Parents and Children

Answer 4

• Fathers cannot pass sex-linked traits to their sons because males receive their X-chromosome from their mothers.
• Mothers can pass sex-linked alleles to both sons and daughters.

Question 5

Sex-Linked Traits

Relationships between X and Y Chromosomes

Answer 5

• Most X-linked genes have no homologous loci on the Y chromosome.
• Most genes on the Y chromosome not only have no X counterparts, but they encode traits found only in males
• The X chromosome is larger than the Y chromosome, therefore there are more traits present on the X chromosome.

Question 6

Pedigrees

Answer 6

tracks a specific trait within family history, squares represent males, circles represent females, unshaded (white) are unaffected, and shaded (black) are affected.

Question 7

Autosomal Recessive Pedigrees

Answer 7

recognized because the trait skips a generation but is still equally shown in both genders.

Question 8

Sex-linked Recessive Pedigrees

Answer 8

recognized by the trait skipping a generation and recognition that the trait is much more common in males. Specifically with this pattern, any affected female must have an affected father.

Question 9

Pedigrees

Complicated Information about Pedigrees

Answer 9

• If the trait is identified as autosomal dominant, all unaffected individuals must be homozygous recessive
• All affected individuals must have at least one dominant allele
• People who marry into the families can either be identified as homozygous recessive or known with only one dominant trait (the other trait is unknown).

Question 10

Carriers

Answer 10

FEMALES who has inherited a recessive allele of a gene that is linked to a genetic condition. However, she doesn’t show traits or symptoms of the condition because her second allele for that gene is normal.