Chapter 11 Flashcards
What did Gregor Mendel do and how was this significant to the scientific community
Gregor Mendel, an Austrian scientist, conducted groundbreaking experiments on pea plants in the mid-19th-century. He established the basic principles of hereditary, uncovering the laws of inheritance. His work laid the foundation for modern genetics and was crucial in understanding how traits are passed from one generation to the next
Describe the relationship between genotypic and phenotypic ratios
The genotypic ratio represents the proportion of different genetic combinations resulting from a genetic cross, while the phenotypic ratio describes the proportion of observable traits within the offspring. In Mendelian inheritance, these ratios often exhibit a direct correspondence, but factors such as multiple gene involvement, epistasis, and environmental influences can lead to variations between genotypic and phenotypic ratios.
What is the law of segregation?
The Law of segregation states that during the formation of gametes, the two alleles for a gene segregate or separate, so each gamete carries only one allele for each gene. This separation ensures that each offspring receives one allele from each parent during fertilization.
How would you work through a test cross of mendelian traits?
To conduct a test cross, an individual with an unknown genotype (but expressing the dominant phenotype) is crossed with a homozygous recessive individual. Analyzing the phenotypic ratios of the offspring helps determine the unknown genotype.
What ar alleles and how do they contribute to genetic diversity produced in meiosis?
Alleles are alternative forms of a gene, located at a specific position on a chromosome. They contribute to genetic diversity during meiosis by segregating and recombining, producing various combinations of alleles in gametes.
What is the difference between a genotype and a phenotype?
Genotype refers to the genetic makeup of an organism, including the combination of alleles it carries. Phenotype is the observable physical or biochemical expression of the genotype.
How would you work through a monohybrid cross? Dihybrid?
In a monohybrid cross, you examine the inheritance of a single trait. In a dihybrid cross, you study the inheritance of two traits simultaneously. Punnett squares can help predict the genotypic and phenotypic ratios of the offspring.
What is the multiplication rule and how could you apply it to monohybrid crosses?
The multiplication rule states that the probability of two independent events occurring together is the product of their individual probabilities. In monohybrid crosses, you multiply the probabilities of individual allele combinations to determine the probability off a specific genotype.
What is the addition rule and how could you apply it to monohybrid crosses?
The addition rule states that the probability of either of two mutually exclusive events occurring is the sum of their individual probabilities. In monohybrid crosses, you add the probabilities of different genotypes to determine the overall probability of a particular phenotype.
What is the difference between incomplete dominance and codominance?
Incomplete dominance occurs when heterozygotes display an intermediate phenotype between the two homozygotes. Codominance occurs when both alleles are expressed fully in the heterozygote, resulting in a distinct phenotype.
What is the relationship between dominance and phenotype?
Dominance determines the phenotypic expression of a particular allele. In a heterozygote, the dominant allele masks the expression of the recessive allele, leading to a specific phenotype.
How are phenotypes affected by genes with more than two allelic forms?
When genes have more than two allelic forms, multiple alleles can influence the phenotype. However, an individual still carries two alleles at a specific gene locus.
What is Pleiotropy
Occurs when a single gene influences multiple traits or has effects in different aspects of an organisms phenotype
How does epistasis affect phenotypes?
Epistasis occurs when the expression of one gene masks or modifies the expression of another gene. it can alter the expected phenotype ratios in a dihybrid cross
What is quantitative variation and how does this relate to polygenic inheritance?
involves traits that exhibit a range of phenotypes. Polygenic inheritance refers to the influence of multiple genes on a single trait, contributing to continuous variation in phenotypes.
