Mendelian Inheritance and Chromosomes

A process where characteristics are inherited independently from each other, not blending together. This principle explains why offspring don't look like an average of their parents.

A physical unit of inheritance that carries a specific genetic instruction from parents to offspring. Genes determine traits like eye color or hair texture.

A specific version of a gene that influences a certain trait. For example, there's a gene for eye color, and its alleles can be brown, blue, or green.

When an organism carries two copies of the same allele for a trait. For example, a plant with two alleles for round seeds would be homozygous for round seeds.

When an organism carries two different alleles for a trait. For example, a plant with one allele for round seeds and one for wrinkled seeds would be heterozygous for seed shape.

The genetic makeup of an organism, represented by the specific combination of alleles it carries. For example, the genotype for a plant with round seeds could be RR or Rr.

The observable characteristics of an organism resulting from its genotype. For example, the phenotype for a plant with round seeds would be having round seeds, regardless of the specific genotype.

A trait that is influenced by only one gene. Such traits often show distinct categories, like having either blue or brown eyes.

Units of DNA that code for a specific amino acid. Three consecutive bases make up a codon.

Changes in the sequence of DNA bases.

A type of mutation where the change in the codon sequence is neither beneficial nor harmful.

The process where the frequency of alleles in a population changes over generations.

The ultimate source of new genetic variation.

A type of gene that regulates other genes, affecting their expression.

A type of regulatory gene responsible for body plan development.

The idea that one gene codes for one specific protein.

A type of farming using iron tools to clear land, where crops are grown until the soil is depleted, and the field is then abandoned.

A mutation in the gene responsible for hemoglobin production, resulting in abnormal red blood cells, especially found in people of West African descent.

A genetic condition where individuals carry the sickle cell trait (AS) and are less likely to be hospitalized with severe malaria. This provides a survival advantage in areas where malaria is prevalent.

The single-celled parasite responsible for causing malaria, transmitted through the bite of infected mosquitos.

A genetic pattern where both alleles of a gene are expressed in a heterozygote, resulting in a phenotype that combines both alleles.

A type of natural selection where individuals with extreme phenotypes are more likely to survive and reproduce, leading to a divergence of the population towards these extremes.

A trait controlled by multiple genes.

Evolutionary changes that occur over long periods, resulting in large-scale transformations such as extinction and speciation.

The study of how gene frequencies change within a population over time.

A hypothesis proposing that evolution occurs primarily through the gradual accumulation of small genetic changes within populations.

A principle stating that allele frequencies remain constant in a population from generation to generation, under specific conditions.

A group of organisms that can interbreed and produce fertile offspring.

The process where two species with a distant common ancestor evolve similar traits due to similar environmental pressures.

The process where two species with a shared ancestor evolve in similar ways due to experiencing similar environmental conditions.

The mixing of genes between two distinct species, often resulting in hybrid offspring.

A measure of an organism's reproductive success, determined by the number of offspring that survive to reach reproductive age.

A change in the genetic makeup of a population over time, resulting from random fluctuations in allele frequencies.

The process where a new population is established from a small number of individuals from a larger population, potentially leading to a different allele frequency distribution.

A drastic reduction in population size due to a catastrophic event, leading to a loss of genetic diversity and potentially altering the allele frequencies.

The genetic variation present in a population is determined by the effective population size, which comprises the individuals that are actually contributing to the next generation.

The process of gene flow between populations, which can prevent genetic divergence and maintain genetic similarity.

A concept that refers to how well an organism is adapted to its specific environment. It is closely related to fitness, but focuses on the characteristics of the organism rather than its reproductive success.

A change in the genetic makeup of a population over time due to differential survival and reproduction of individuals with certain traits.

A type of natural selection where the average trait value of a population shifts towards one extreme. This occurs when one phenotype is consistently favored over others.

The medium ground finch population on the Galapagos Islands changed dramatically during a severe drought. Larger beaked birds were better able to eat the remaining seeds, leading to an increase in average beak size in the next generation. The change in phenotype was due to a change in the environment.

A type of natural selection where individuals with intermediate traits have the highest probability of survival. This can lead to the maintenance of genetic diversity within a population.

Sickle cell anemia is a genetic disorder where red blood cells have an abnormal shape. Although individuals with two copies of the sickle cell allele (SS) experience severe health problems, individuals with one copy of the sickle cell allele (AS) have increased resistance to malaria. This leads to a balanced polymorphism, where both the S and A alleles are maintained in the population.

Organisms with advantageous traits are more likely to survive and reproduce, passing on those traits to their offspring. This leads to a gradual shift in the population towards those advantageous traits.

The genetic variation within a population is critical for its ability to adapt to changing environments. Gene flow can increase genetic diversity within a population.

The process where genetic information is exchanged between populations. This exchange can lead to a decrease in genetic differences between populations.

A population that has not been exposed to a particular virus or pathogen. This population might be more susceptible to disease.

The ability of a virus to cause disease. A virus that is less virulent is less likely to cause severe illness.