23 & 24 - Inheritance

Question 1

Autosomal recessive

Answer 1

• Equal in male and female
• Tend to skip generations
• Likely to appear among offspring of related parents
• Affected offspring born to unaffected parents
• CF

Question 2

Autosomal dominant

Answer 2

• appear equally in sexes, both can transmit
• unaffected dont transmit
• affected have affected parent
• does not skip generations
• huntingtons

Question 3

X linked recessive

Answer 3

• Affected male doesn’t pass to sons, pass to daughter who is unaffected but passes to sons who are
• frequent in males
• never passed from father to son
• skips generations
• Haemophilia

Question 4

X linked dominant

Answer 4

• Do not skip generations
• Affected males pass to all daughters, no sons
• Affected heterozygous females pass to half sons half daughters
• Rickets

Question 5

Y linked

Answer 5

• only appears in males
• All male offspring of an affected male are affected

Question 6

Mitochondrial inheritance

Answer 6

ovum contributed mitochondria therefore all children affected. males do not pass on disease

Question 7

Gene

Answer 7

An inherited region of DNA that helps determine a characteristic

Question 8

Allele

Answer 8

One of two or more alternative forms for a gene

Question 9

Locus

Answer 9

Specific place on a chromosome occupied by an allele

Question 10

Pleiotropy

Answer 10

Genes having multiple phenotypic effects. (e.g. CF or sickle cell anemia)

Question 11

mosaicism

Answer 11

occurs when an organism has 2 or more genetically different sets of cells in their body. Can be for chromosomal or single gene disorders and can effect somatic or germline tissues.

Question 12

Mendel’s first law

Answer 12

• Segregation of alleles.
• Cells contain 2 alleles of each gene which seperate during meiosis
• Gametes carry one copy of each gene (random)

Question 13

Mendel’s second law

Answer 13

• Law of independent Assortment
• Gene pairs on different chromosome pairs assort independently at meiosis (random)

Question 14

Linked genes

Answer 14

Genes located close together on same chromosome. Do not assort independently

Question 15

Epistatic

Answer 15

A gene that affects, prevents, or masks the expression of a gene at another locus

Question 16

codominance

Answer 16

Two equally dominant alleles expressed concurrently. Has both alleles independently expressed in the heterozygote

Question 17

consanguinity

Answer 17

mating between two closely related parents

Question 18

Heteroplasmy

Answer 18

the presence of more than one type of mitochondrial DNA genome within a cell.

Question 19

Homoplasmy

Answer 19

Identical copies of mitochondrial DNA within a cell

Question 20

Complete dominance

Answer 20

where the heterozygote allele that is regarded as dominant completely masks the effect of the allele that is recessive

Question 21

Incomplete dominance

Answer 21

both alleles of a gene at a locus are partially expressed, resulting in an intermediate or different phenotype

Question 22

Epigenetics

Answer 22

Heritable markers that do not involve changes to the underlying DNA sequence.

Question 23

Penetrance

Answer 23

The extent to which a particular gene is expressed in the phenotypes of individuals carrying it. Measured by the proportion of carriers showing the characteristic phenotype.