Chapter 2 - Genes

Question 1

Autosomal dominant

Answer 1

rare. Affected offspring produced by an affected heterozygous parent and normal parent

Question 2

Autosomal dominant - characteristics

Answer 2

■ Affected persons have an affected parent
■ Affected persons mating with normal persons have affected and unaffected offspring in equal proportions
■ Males and females are equally affected

Question 3

● Autosomal recessive - characteristics

Answer 3

■ Siblings only
■ Males/female equally affected
■ Reoccurrence risk is 1 in 4 for every birth
■ Both parents of affected child carry the recessive allele
■ Parents may be blood relatives

Question 4

AUtosomal recesive

Answer 4

abnormal allele is recessive. For the trait to be expressed, person must be homozygous or abnormal allele

Question 5

x-linked dominant

Answer 5

some genetic conditions are caused by mutations in genes located on the sex chromosomes, and this mode of inheritance is termed sex linked. Rare and affected male transmits gene to all of his daughters and none to son

Question 6

X-linked recessive

Answer 6

: predominantly males. Affected males transmit to daughters. Sons or female carriers have 50% chance of being affected.

Question 7

Recurrence risk

Answer 7

the probability that an individual will develop a genetic disease. An example is when1 parent is affected by an autosomal dominate disease and is heterozygote and the other parent is unaffected the child’s risk is 50/50 but each birth is an independent event.

Question 8

Penetrance

Answer 8

perccentage of individuals with a specific genotype who also express the expected phenotype. Incomplete penetrance means that individuals who have the disease-causing genotype may not exhibit the disease phenotype at all, even though the genotype and the associated disease may be transimitted to the next generation. example is Retinoblastoma most common maglignant eye tumor affecting children, typically exhibits incomplete penet rance of the disease causing genotype.

Question 9

Expressivity

Answer 9

perccentage of individuals with a specific genotype who also express the expected phenotype. Incomplete penetrance means that individuals who have the disease-causing genotype may not exhibit the disease phenotype at all, even though the genotype and the associated disease may be transimitted to the next generation. example is Retinoblastoma most common maglignant eye tumor affecting children, typically exhibits incomplete penet rance of the disease causing genotype.

Question 10

sex limited traits

Answer 10

Those traits which are found exclusively in males or females. This is due to anatomic differences. An example of this would be inherited uterine defects. Only females experience this trait. Testicular defects which are inherited would only be experienced by males.

Question 11

sex-influence traiteds

Answer 11

These are traits which are more common in either males or females, but can occur in both. For example, breast cancer is usually found in females, but males can, although rare, be affected by this disease as well.

Question 12

Peidgree

Answer 12

A disease pedigree documents family relationships and shows which family members are at risk for inheriting a disease.

Question 13

Pedigree complications

Answer 13

such as incomplete penetance, delayed onset, varried expression, and sex-influenced traits makes it difficult to determine the mode of inheritance.

Question 14

Gene mapping

Answer 14

This is the process of finding the location of certain human genes, and has increased our understanding of how certain diseases work and help with the diagnosis of these diseases.

Question 15

polymorphic

Answer 15

traits resulting from several genes acting together.

Question 16

Mulltifactorial inheritance:

Answer 16

When the environmental factors influence the expression of
the trait. Many multifactorial and polygenic traits tend to follow a normal distribution in
populations (normal bell-shaped curve).