Module 6
1. Module 6
1.7. Page 5
Module 6—Mendelian Genetics: The Transmission of Traits to the Next Generation
Lesson Summary
During this lesson you were to focus on the following questions:
- What is the basic language of genetics?
- How does the work of Mendel explain the basics of classical genetics?
By reading, and watching the videos, you have seen and heard the language of genetics being used. With your creation of a study dictionary or flash card set, you should now have begun to put that language into practice. Keep reviewing your flash card set, and add the new words that will be presented in each upcoming lesson.
Mendel used careful scientific methods to analyze the inheritance of traits in garden peas. He made clear observations, conducted many experimental trials, and worked in a controlled environment. It is thanks to his work that we were able to begin to understand just how genes are responsible for our characteristics.
Lesson Glossary
Consult the glossary in the textbook for other definitions that you may need to complete your work.
contrasting characteristic: a trait that has two alleles that are expressed in a different way (e.g., the trait for height in pea plants can have the contrasting characteristics of tall or short)
dominant: if two alleles are present, the allele that is expressed is the dominant one (e.g., if an individual has both tall and short alleles, but is tall, then tall is dominant over short)
F1 generation: offspring of the P1 generation; F stands for filial generation—meaning brothers and sisters
F2 generation: offspring produced as a result of individuals of the F1 generation mating with other individuals of the F1 generation
factor: the term used by Gregor Mendel to explain inheritance of a trait; today we use the term gene
filial: the offspring of a cross
genotype: what the genes say; two symbols that indicate which alleles the individual has for a particular trait (e.g., Tt)
heterozygous: a genotype where the alleles are different (e.g.,Tt)
homozygous (true breeding): a genotype where both alleles are the same (e.g. ,TT is homozygous dominant, tt is homozygous recessive)
hybrid: the offspring of two parents with different inheritable traits; often termed heterozygous
inheritable trait: a characteristic that is determined by genes, not the environment; a trait that is capable of being passed from parent to offspring
law of segregation: the two genes that an organism has for each trait are separated during meiosis so that only one gene can enter a gamete; explains why body cells are diploid, but gametes are haploid
monohybrid: an organism that is heterozygous for one trait (e.g., Tt)
P1 generation: the first set of parents; parents of the F1 generation
phenotype: the observable characteristic of the organism (e.g., tall height or short height; is determined by genotype) (e.g., the Tt genotype results in a tall phenotype)
pure: an individual with both alleles for a trait being dominant, or recessive
recessive: if two alleles are present, the allele that is hidden is recessive
selective breeding: choosing stock because of its physical, behavioural, or functional characteristics
trait: a characteristic
true breeding: organisms that produce offspring that express the same trait generation after generation; organisms are homozygous for a trait