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.
What does diploid mean?
A cell or organism with two sets of chromosomes (one from each parent), typical of somatic cells.
What does haploid mean?
A cell or organism with one set of chromosomes, typical of gametes (sperm and egg cells).
What is a zygote?
The cell formed by the fusion of two gametes during fertilization, containing a full set of chromosomes.
What is a gene pool?
The complete set of genetic information within all individuals in a population.
What is selection pressure?
External factors that affect an organism’s survival, influencing natural selection (e.g., predators, climate).
What is speciation?
The process through which new species arise due to genetic isolation and evolutionary processes.
What is genetic recombination?
The process of forming new combinations of alleles during meiosis, including crossing over and independent assortment.
What is phenotypic variation?
Differences in physical appearance or function among individuals in a population, often due to genetic and environmental factors.
What is somatic mutation?
A mutation occurring in a somatic (non-reproductive) cell that affects only the individual and is not passed to offspring.
What is germline mutation?
A mutation in a reproductive cell that can be inherited by offspring, potentially affecting future generations.
What is a point mutation?
A mutation affecting a single nucleotide in the DNA sequence, which may be silent, missense, or nonsense.
What is a silent mutation?
A point mutation that does not change the amino acid sequence of a protein and therefore has no effect on its function.
What is a missense mutation?
A mutation that changes one amino acid in a protein sequence, potentially altering the protein’s function.
What is a nonsense mutation?
A mutation that converts a codon for an amino acid into a stop codon, resulting in a shortened, often nonfunctional protein.
What is a frameshift mutation?
A mutation caused by insertions or deletions of nucleotides that alter the reading frame, leading to a completely different amino acid sequence.
What is genetic linkage?
The tendency for genes located close to each other on the same chromosome to be inherited together.
What is pleiotropy?
A genetic scenario where one gene influences multiple, seemingly unrelated phenotypic traits.
What is epistasis?
An interaction between genes where the effect of one gene is modified or masked by another gene.
What is a sex-linked trait?
A trait associated with a gene that is located on a sex chromosome, often leading to different expression in males and females.
What is an autosomal trait?
A trait associated with a gene located on an autosome (non-sex chromosome), typically affecting males and females equally.
What is genetic equilibrium?
A state where allele frequencies in a population remain constant over generations in the absence of evolutionary forces.
What is the Hardy-Weinberg principle?
A principle stating that allele and genotype frequencies in a population remain constant if no evolutionary influences are acting.
What is adaptation?
A heritable trait that enhances an organism’s ability to survive and reproduce in its environment.
What is fitness?
The reproductive success of an organism in passing its genes to the next generation, relative to others in the population.
What are homologous chromosomes?
A pair of chromosomes, one from each parent, that contain the same genes but may have different alleles.
What are recombinant chromosomes?
Chromosomes that have undergone crossing over, resulting in a mix of alleles from both parental chromosomes.
What is evolution?
The change in allele frequencies in a population over time, often leading to adaptation and speciation.
What is artificial selection?
The intentional breeding of organisms to enhance or suppress specific traits.
What is genetic isolation?
A state where two populations cannot interbreed, often leading to speciation due to a lack of gene flow.
What is a monohybrid cross?
A genetic cross focusing on the inheritance of a single trait controlled by two alleles.
What is a dihybrid cross?
A genetic cross involving two traits, where each trait is controlled by two alleles, following Mendel’s law of independent assortment.
What is a locus?
The specific physical location of a gene or allele on a chromosome.
What is a carrier?
An individual who has one copy of a recessive allele that can be passed to offspring but does not express the trait.
What is genetic engineering?
The manipulation of an organism’s genome using biotechnology, often to add or modify traits.
What is biotechnology?
The use of living organisms or their components to develop products, often used in genetics for research and applications.
allele frequency
the proportion of a specific allele amoung all allele copies in an population. Changes in the allele frequency over time can indicate evolutionary changes within the population
