Chapter 4

What is the locus of a gene?

the location of a specific gene or group of genes

​One goal of pedigree analysis is to determine: 

whether a gene has a dominant or recessive pattern of inheritance

When a dominant allele is paired with a recessive allele, which one will show in a persons phenotype?

the dominant gene

​There are ____ basic patterns of Mendelian inheritance.

5

​Y-linked traits are:

carried only by males and transmitted only to males

​If a pedigree of several generations shows only females affected by a particular trait, it cannot be a(n) ____ trait.

Y-linked

For this inheritance patter (autosomal recessive), what would happen if the offspring from the bottom right square (rr) has children with another affected individual (rr)?

Their offspring will have a 100% chance of being affected by the disorder.

​Almost all cases of cystic fibrosis, a(n) ____ genetic disorder, are the result of mating between two unaffected parents.

autosomal recessive

What happens to the recessive allele in heterozygotes of dominant disorders?

It gets masked by the allele for the dominant disorder.

​The chance of a child having albinism when both of his parents are heterozygous for the disorder is ____ percent.

25

​In autosomal dominant inheritance:

two affected individuals may have unaffected children

​One characteristic of an autosomal dominant trait is that:

every affected individual has at least one affected parent

If person III-2 has children with an unaffected individual, what are the chances of their child having this disorder? (Go back to the last slide if you need to!!)

50% skip

Camptodactyly causes:

bent, immobile little fingers

​The gene responsible for Marfan syndrome encodes a protein associated with:

connective tissue

What are the chances of 2 dwarfs having a normal sized child?

25%

Which parent's chromosome is responsible for gender?

father

If a man expresses an X-linked recessive trait:

his mother was heterozygous or homozygous for the trait

If the boy on the right eventually has a daughter, will she be colorblind?

it depends on the mother's allele

What is a distinct pedigree characteristic of an X-linked dominant disorder?

twice as many girls are affected 

If person 3 in generation III has a son with an UNaffected female, what are the chances of the son having the disorder? 

0% skip

___________ is a condition in which only one copy of a gene or DNA sequence is present in diploid cells.

hemizygous

​Approximately ____ Y-linked genes have been discovered.

60

If person 9 in generation IV has a daughter, what are the chances of her having the disorder?

0% skip

​Mitochondria are transmitted from mothers to:

all of their children through the cytoplasm of the egg

When person 5 of generation 3 has children, what are the chances he will pass it on to his children?

0% skip

Autosomal recessive disorders show __________ penetrance.

incomplete

​The phenotype of ____ does not develop until adulthood.

Huntington's disease

Common recessive alleles present in a family can result in a pedigree that looks like ____ inheritance.

autosomal dominant