Effective Team Communication Quiz

Study Notes

Mendelian genetics analyzes the inheritance of physical traits from parents to offspring.
It is also called Transmission Genetics.
Gregor Mendel was a monk, mathematician, and gardener who conducted controlled breeding experiments.
Mendel's pea plants were a good model organism for controlled breeding.
Key characteristics of Pisum sativum (the pea plants) that made them suitable for Mendel's experiments were short generation time, multiple offspring per mating, easily scored characteristics, and easily controlled matings (both cross-breeding and self-breeding possible).

Traits are often impacted by a single gene.
Each gene often has two variable forms (alleles).
Monohybrid crosses produce a 3:1 phenotypic ratio and a 1:2:1 genotypic ratio. This demonstrates the law of dominance and segregation.
Dihybrid crosses produce a 9:3:3:1 phenotypic ratio and a 1:2:4:2:1:2:1:2:1 genotypic ratio. This supports the Law of Independent Assortment.

1A: Tall (TT) x dwarf (tt) = F1 generation all tall (Tt). Conclusion: Tall (T) is dominant to dwarf (t).
1B: Tall (Tt) x Tall (Tt) = F2 generation 75% tall and 25% dwarf. Conclusion: Organisms possess a pair of genetic factors, only one member of each pair enters each gamete, and the paired nature is restored in the offspring. This is the principle of segregation.
2: Tall, red (RRTT) x dwarf, white (rrtt) = F1 all tall, red (RrTt); F1 x F1 = F2 generation 9-tall red, 3-tall white, 3-dwarf red, and 1-dwarf white. Conclusion: Each pair of genetic factors assorts into gametes independently. This is the principle of independent assortment.

Anaphase I of meiosis is the source of segregation, allowing haploid cells (gametes) to be formed without centromere breakage.
Random alignment of homologous chromosomes in metaphase I of meiosis leads to very diverse gametes and is the source of independent assortment.

Monohybrid Cross: A mating experiment that follows the inheritance pattern of one trait.
Dihybrid Cross: A mating experiment that follows the inheritance pattern of two traits simultaneously
Self-Cross: A genetic cross between genetically identical organisms for a particular trait of interest.
Genotype: The pair of genetic factors—or alleles—an organism has for a particular trait (e.g., TT, Tt, or tt).
Phenotype: The observable physical trait of an organism.
Allele: One of the possible variants of a trait's expression (e.g., tall [T] and dwarf [t]).
Dominant: The allele of a gene that is observed in hybrid organisms (e.g., Tall in Tt).
Recessive: The allele of a gene that is not observed in hybrid organisms (e.g., dwarf in Tt).
Homozygous: Describes a genotype in which the two alleles are identical (e.g., TT or tt).
Heterozygous: Describes a genotype in which the two alleles are different (e.g., Tt).

Incomplete dominance: Neither allele is truly dominant; heterozygotes exhibit an intermediate phenotype.
Codominance: Both alleles are dominant; heterozygotes exhibit both alleles simultaneously (e.g., blood type AB).
Multiple alleles: More than two variants/alleles exist in a population (e.g., blood type).
Polygenic inheritance: Many characteristics are controlled by the combined influence of several genes (e.g., human skin color).
Pleiotropy: One gene can affect multiple phenotypes (e.g., sickle-cell anemia impacting multiple biological processes).
Sex-linked traits: Traits determined by genes located on the sex chromosomes (e.g., color blindness, hemophilia).
Epistasis: One genotype can block the expression of a genotype of a second gene resulting in altered phenotypic ratios.
Complementation: Determining whether different mutations in a gene product produce the same phenotype, revealing whether they are on the same gene or different genes.

Hemoglobin is the protein that transports oxygen in red blood cells.
HbS and HbS alleles are codominant.
The genotypes: HbA/HbA (normal); HbS/HbS (severe anemia); HbA/HbS (have sickle-cell trait).

Pedigree analysis: Charts that track the inheritance of a trait across generations.
Sex determination: How genetic and environmental factors affect determining sex. Various mechanisms include, but are not limited to, autosomal and chromosomal sex determination, as well as environmental sex determination, and sex determination via multiple alleles and ploidy.
Dosage compensation: System that balances gene expression between the sexes despite different numbers of sex chromosomes.
Different types of inheritance demonstrate that how you apply the concept of dominance depends on the level of observation (e.g., organismal vs. cellular/molecular level).