Patterns Of Inheritance Flashcards
What is Mendelian inheritance?
A: Mendelian inheritance refers to the patterns of inheritance first described by Gregor Mendel, including autosomal dominant, autosomal recessive, and sex-linked inheritance.
What is a pedigree?
A: A pedigree is a diagram that represents family relationships and is used to track the inheritance of genetic traits.
What is an autosomal dominant disorder?
A: An autosomal dominant disorder is caused by a mutation in a single copy of a gene on an autosome, meaning only one affected parent is needed for inheritance.
How does autosomal recessive inheritance differ from dominant inheritance?
A: Autosomal recessive disorders require two copies of a mutated gene (one from each parent) for the disease to manifest, whereas autosomal dominant disorders require only one copy.
What is X-inactivation (Lyonization)?
A: X-inactivation is the process by which one of the two X chromosomes in females is randomly inactivated to balance gene expression with males.
Autosomal dominant disorders often appear in
every generation.
Autosomal recessive disorders are more likely to appear in
offspring of consanguineous (related) parents.
X-linked recessive disorders primarily affect
males.
Huntington’s disease is an example of
age-dependent penetrance.
The Hardy-Weinberg principle predicts genotype frequencies in a
population.
X-linked dominant disorders only affect males.
False – They can affect both males and females, but females may have milder symptoms due to X-inactivation.
Carriers of autosomal recessive diseases usually show symptoms.
False – Carriers typically do not show symptoms but can pass the mutated allele to their offspring.
Autosomal dominant disorders always have 100% penetrance.
False – Some disorders show reduced or age-dependent penetrance.
Inbreeding increases the likelihood of recessive genetic disorders.
True – Inbreeding increases homozygosity, raising the chances of inheriting recessive conditions.
In an autosomal dominant disorder, an affected individual has a __________% chance of passing the mutation to each offspring.
A: 50%
The most common mutation in cystic fibrosis is the deletion of __________ at position 508 in the CFTR gene.
A: Phenylalanine
A pedigree showing affected males in every generation but few affected females suggests __________ inheritance.
A: X-linked recessive
A genetic condition that worsens over successive generations due to increasing repeat expansions is called __________.
A: Anticipation
Which of the following is a characteristic of autosomal recessive inheritance?
A) Appears in every generation
B) Affected individuals often have unaffected parents
C) Affects males only
D) More common in females than males
A: B) Affected individuals often have unaffected parents.
What genetic principle explains why two carriers of a recessive disorder have a 25% chance of having an affected child?
A) Mendelian segregation
B) Linkage disequilibrium
C) Genetic drift
D) X-inactivation
A: A) Mendelian segregation.
Which disorder is caused by a triplet repeat expansion?
A) Cystic fibrosis
B) Sickle cell anemia
C) Huntington’s disease
D) Hemophilia
A: C) Huntington’s disease.
What is the probability of two heterozygous carriers of an autosomal recessive disease having an affected child?
A) 10%
B) 25%
C) 50%
D) 75%
A: B) 25%.
A child is born with a genetic disorder, but neither parent has the condition. What is the most likely inheritance pattern?
A: Autosomal recessive.
A male has an X-linked disorder but none of his sons are affected. What explains this pattern?
A: X-linked traits are inherited from the mother, and males pass their Y chromosome to sons.
