Untitled Quiz

Study Notes

Recognize genetic terms related to mode of inheritance
Compare and contrast autosomal, sex-linked, dominant, and recessive inheritance
Practice predicting probabilities of genotypes and phenotypes based on parental genotypes and inheritance patterns.
Describe examples of Mendelian inheritance

Segregation: The separation of allele pairs (different traits of the same gene) during meiosis, allowing for their specific transfer to separate gametes.
Pedigree: A family history diagram illustrating family members, their relationships to the proband, and their relation to a particular hereditary condition.

1- Law of Segregation: Alleles segregate from each other during meiosis (gamete formation), with only one allele present in each gamete. Which allele is passed on is random.
2- Law of Dominance: Dominant alleles mask recessive alleles. A cross between homozygous dominant and homozygous recessive will show the dominant phenotype, but the genotype will be heterozygous.
3- Law of Independent Assortment: During metaphase I of meiosis, chromosomes randomly distribute at the equator, resulting in daughter cells with different combinations of maternal and paternal chromosomes.

F1 generation: The first generation resulting from a cross between two organisms (e.g., homozygous dominant and homozygous recessive).
F2 generation: The second generation resulting from a cross between two F1 organisms (e.g., heterozygous).

Used to predict the outcome of simple genetic crosses.
Determine relative proportions of genotypes and phenotypes of offspring.
Includes one-factor crosses and two-factor crosses (e.g., crosses involving traits like plant height and seed color).

Standardized symbols for various family relationships and traits (e.g., male, female, affected, unaffected, marriage, children, deceased, etc.)

One mutated copy of a gene is sufficient to cause the condition.
Phenotype appears in every generation.
Males and females are equally affected; male-to-male transmission is possible.
Each affected individual usually has one affected parent.
Affected individual has a 50% chance of having an affected child.
Can arise from a new mutation.
Demonstrates characteristics such as no skipping of generations, no sexual predilection, or normal offspring not transmitting the disease, and usually affects structural proteins.
Examples of conditions include Achondroplasia, Marfan syndrome, and Osteogenesis imperfecta.
Concepts of penetrance and expressivity are discussed.

Two mutated copies of a gene are necessary for the condition (homozygous).
Males and females are equally affected.
Both parents are unaffected carriers.
With each pregnancy, carrier couples have a 25% risk of an affected child, 50% risk of a carrier, and 25% of a normal child..
Examples include cystic fibrosis, sickle cell anemia, Tay-Sachs disease, and B thalassemia.

Both males and females express the disease if the mutation is present
Affected males cannot pass the condition to their sons but do pass it to all their daughters.
Affected females have a 50% chance of an affected child.
Examples include Vitamin D-resistant rickets and Fragile X syndrome.

Clinical phenotype is expressed in males and usually not in females.
One mutant copy of a gene on the X chromosome is enough to manifest the condition in males.
No male-to-male transmission, but sons of affected males will not be affected.
Unaffected males don't transmit.
The daughters of an affected male always carry one copy of the mutated gene.
Carrier females have a 50% chance of having an affected son and a 50% chance of having a carrier daughter
Examples are Haemophilia A, Haemophilia B, and Duchenne muscular dystrophy.