Who was Gregor Mendel and why is he important to genetics?

Gregor Mendel was a 19th-century Austrian monk who discovered the mathematical laws of inheritance by breeding pea plants — his work, ignored for 35 years, became the foundation of modern genetics Gregor Mendel was the scientist who discovered the double helix structure of DNA in 1953 Gregor Mendel was a physician who identified the first genetic disease by studying blood types Gregor Mendel was an evolutionary biologist who worked alongside Charles Darwin

What is Mendel's Law of Segregation?

Each organism has two copies of each gene (one from each parent), and these copies separate during the formation of sex cells — each gamete receives only one copy Genes from the same parent always stay together and are inherited as a unit The two copies of a gene blend together in offspring to produce intermediate traits Only one parent's genes are passed to offspring — the dominant parent's genes take over

What is Mendel's Law of Independent Assortment?

Genes for different traits assort independently during gamete formation — the inheritance of one gene does not influence the inheritance of another gene located on a different chromosome Genes are always inherited together as complete sets from one parent The inheritance of one gene always determines the inheritance of all other genes Independent assortment means genes can spontaneously change between generations

What is the difference between dominant and recessive alleles?

A dominant allele is expressed whenever present (even one copy is enough); a recessive allele is only expressed when two copies are present — a dominant allele 'masks' a recessive one Dominant alleles are more common in a population; recessive alleles are rare Recessive alleles are expressed in males; dominant alleles are expressed in females Dominant alleles code for stronger traits; recessive alleles code for weaker traits

What is co-dominance and incomplete dominance?

Co-dominance: both alleles are fully expressed simultaneously (e.g. AB blood type shows both A and B markers). Incomplete dominance: the two alleles blend to produce an intermediate phenotype (e.g. red + white flowers produce pink) Co-dominance and incomplete dominance both mean that neither allele is expressed Incomplete dominance means one allele is stronger but not fully dominant — it partially suppresses the other Co-dominance only occurs in blood type; all other traits follow simple dominance

What is a Punnett square and how is it used?

A Punnett square is a grid that predicts the probability of each genotype and phenotype in offspring by systematically combining the gametes each parent can produce A Punnett square is a device that actually determines which genes offspring will inherit A Punnett square is a diagram that shows which parent's traits are dominant A Punnett square can only be used for traits controlled by a single gene with two alleles

What is polygenic inheritance?

Polygenic inheritance is when a single trait is controlled by multiple genes — this produces a continuous range of phenotypes (like a bell curve) rather than distinct categories Polygenic inheritance means one gene controls many different traits simultaneously Polygenic inheritance only occurs in plants, not in animals or humans Polygenic inheritance means a trait is inherited from both parents equally

What is sex-linked inheritance?

Sex-linked traits are encoded on sex chromosomes (usually the X chromosome) — because males have only one X chromosome, they express X-linked recessive traits more often than females Sex-linked traits are only inherited from the mother — fathers pass no traits through sex chromosomes Sex-linked traits only affect a person's biological sex characteristics, not other features Males and females are equally likely to express sex-linked recessive traits

Why can two brown-eyed parents have a blue-eyed child?

If both parents carry a recessive allele for blue eyes (they are heterozygous), each parent can pass that allele to a child — if the child inherits the recessive allele from both parents, they will have blue eyes It is impossible for two brown-eyed parents to have a blue-eyed child Blue eyes can spontaneously appear due to a new mutation in each generation The child's eye color is determined by the grandparents' eye color, not the parents'

What is a genetic disorder?

A genetic disorder is a condition caused by a change (mutation) in one or more genes or chromosomes — it can be inherited from parents or arise as a new mutation Genetic disorders are always inherited from both parents — you cannot have a genetic disorder from a new mutation Genetic disorders only affect appearance, not internal organs or brain function Genetic disorders can be caught from other people, like infections