What is Mendel’s contribution to genetics?
Mendel’s experiments with peas explain how genes are passed from one generation to another, including family characteristics and inherited illnesses.
What is a genotype?
The genotype an organism’s unique combination of alleles or the genetic makeup of an organism, inherited from its parents.
What is a phenotype?
The phenotype refers to the observable characteristics or traits in an individual based on the expression of their genes.
What does homozygous mean?
Homozygous means having the same alleles.
What does heterozygous mean?
Heterozygous means having different alleles.
What is the difference between dominant and recessive alleles?
Dominant alleles are always expressed.
Recessive alleles will be masked by dominant alleles and are only expressed when an individual has two copies of the alleles.
How are dominant and recessive alleles represented?
Dominant alleles are written as capital letters (e.g., AA), while recessive alleles are written as lower case letters (e.g., aa).
What is a Punnett square?
A Punnett square is a table that shows all possible outcomes for a genetic cross between two individuals with known genotypes.
What is sex linkage in genetics?
Sex linkage refers to traits determined by genes located on the sex chromosomes (X and Y in humans).
How does sex linkage affect inheritance in males and females?
Inheritance and expression of sex-linked traits differ between males and females due to their different combinations of sex chromosomes.
As these characteristics are controlled by genes on the X chromosome, they are more likely to occur in Males as there is no corresponding allele on the Y chromosome.
What are some examples of sex-linked traits?
Examples include colour blindness, haemophilia, muscular dystrophy, and eye colour in Drosophila.
What are autosomal dominant traits?
Autosomal dominant traits pass from one parent to their child.
Only require one copy of the dominant allele to express the trait.
Eg.Huntington’s disease, Marfan syndrome
What are autosomal recessive traits?
Autosomal recessive traits pass from both parents to their child.
These require two copies of the recessive allele to express the trait.
Eg. cystic fibrosis, sickle cell anemia.
What is incomplete dominance?
Incomplete dominance occurs when neither of the two alleles is completely dominant, resulting in a phenotype that is a combination of both.
What are the indicators of whether a trait is dominant or recessive?
Dominant traits: Affected individuals have at least one affected parent. Recessive traits: Unaffected parents can have affected offspring.
