Genetic Variation Flashcards
What is an allele?
A variant form of a gene. Alleles can be dominant or recessive and are responsible for genetic variation.
What is a gene?
A segment of DNA that codes for a specific protein or function, determining individual traits.
What is a chromosome?
A structure made of DNA and protein that contains genes. Humans have 46 chromosomes in each somatic cell.
What is a genotype?
The genetic makeup of an organism, consisting of alleles inherited from both parents (e.g., Aa, BB).
What is a phenotype?
The physical expression of an organism’s genotype, including observable traits.
What does homozygous mean?
Having two identical alleles for a particular gene (e.g., AA or aa).
What does heterozygous mean?
Having two different alleles for a particular gene (e.g., Aa).
What is a dominant allele?
An allele that expresses its trait in the phenotype even when only one copy is present (e.g., A in Aa).
What is a recessive allele?
An allele that is masked by a dominant allele and only expressed in the phenotype when two copies are present (e.g., aa).
What is codominance?
A form of inheritance where both alleles are fully expressed in the phenotype of a heterozygote (e.g., AB blood type).
What is incomplete dominance?
A genetic situation where neither allele is dominant, resulting in a blending of traits in the heterozygote (e.g., red and white flowers produce pink).
What is a mutation?
A change in the DNA sequence, which can introduce new genetic variations.
What is genetic drift?
Random changes in allele frequencies in a population, often having a more significant effect in small populations.
What is gene flow?
The transfer of genetic material between different populations, increasing genetic variation within the population.
What is natural selection?
A process where organisms with favorable traits are more likely to survive and reproduce, leading to changes in allele frequencies over time.
What is sexual reproduction?
The process of creating offspring through the combination of male and female gametes, resulting in genetic variation.
What is crossing over?
The exchange of genetic material between homologous chromosomes during meiosis, creating new allele combinations.
What is independent assortment?
The random distribution of homologous chromosomes during meiosis, resulting in genetic variation.
What is fertilization?
The fusion of male and female gametes to form a zygote, combining alleles from both parents.
What are polygenic traits?
Traits controlled by two or more genes, often resulting in a continuous range of phenotypes (e.g., skin color, height).
What is genetic variation?
The diversity in gene frequencies within a population, essential for evolution and adaptation.
What is the bottleneck effect?
A sharp reduction in population size due to environmental events, reducing genetic variation.
What is the founder effect?
Reduced genetic variation that occurs when a small group of individuals establishes a new population.
What is meiosis?
A type of cell division that reduces the chromosome number by half, creating four genetically unique gametes.