Week 10

Question 1

Autosomal dominant Pattern

Answer 1

• A pattern of inheritance in which an affected individual has one copy of a
  mutant gene and one normal gene on a pair of autosomal chromosomes.
• Examples of autosomal dominant diseases include Huntington disease

Question 1

Autosomal Linkage

Answer 1

• An Autosomal chromosome is any chromosome except for the sex chromosomes.
  (Humans have 44 homologous autosomal chromosomes, or autosomes.)
• Autosomal linkage refers to inheritance of the genes on a given autosomal
  chromosome.
• Genes that are located on the same chromosome are
  called linked genes. Alleles for these genes tend to
  segregate together during meiosis, unless they are
  separated by crossing-over.
• Crossing-over occurs when two homologous
  chromosomes exchange genetic material during meiosis
• The closer together two genes are on a chromosome,
  the less likely their alleles will be separated by crossingover.
• Linkage explains why certain characteristics are
  frequently inherited together. For example, genes for
  hair color and eye color are linked, so certain hair and
  eye colors tend to be inherited together, such as blonde
  hair with blue eyes and brown hair with brown eyes

Question 2

Autosomal recessive pattern

Answer 2

• Autosomal recessive diseases require that the individual have two copies of
  the mutant gene
• The parents of an individual with an autosomal recessive condition each
  carry one copy of the mutated gene, but they typically do not show signs
  and symptoms of the condition. Autosomal recessive disorders are typically
  not seen in every generation of an affected family.
• E.g. Cystic fibrosis, sickle cell disease

Question 3

Epistasis

Answer 3

• In epistasis, the interaction between genes is antagonistic, such that
  one gene masks or interferes with the expression of another.
• The alleles that are being masked or silenced are said to be hypostatic
  to the epistatic alleles that are doing the masking.
• Often the biochemical basis of epistasis is a gene pathway in which the
  expression of one gene is dependent on the function of a gene that
  precedes or follows it in the pathway.