BIOL 2500 - Topic 3 (part 1)

Genetics

The study of inheritance

To understand biology, we often try to understand individual _________ properties

Biological

Individual biological properties we try to understand

1.) Characters

2.) Gene discovery

Characters

Aka traits, which are attributes of individual members of a species that is inherited and can be measured/defined

Character example

1.) Eye colour

2.) Blood type

Gene discovery

The process of determining which genes are responsible for any given trait

Method of gene discovery

Studying single-gene inheritance patterns

Single-gene inheritance patterns

1.) Refers to patterns where a single gene corresponds to a single trait/character.

2.) It analyzes heritable variants and compares it with the wild type

Wildtype

The most common form of the trait in nature

Mutant variants

Heritable variants that differ from the wild type, usually arising from mutations

Are wild types and mutants the same thing as dominant and recessive

No, they are not the same thing, because the wild type can be a recessive gene, while the mutant variant is the dominant gene.

Phenotypes

The physical alternative forms of a trait, including the wild type and all heritable variants

General steps of analyzing a trait

1.) Gather mutants

2.) Cross (mate) the mutant individuals to wildtype individuals

3.) Deduce the functions of genes at the molecular level and see how gene interactions contribute to the trait

Why cross mutant and wildtype individuals

To see if their offspring show the phenotypic ratios expected for single gene inheritance, which can potentially tell us if it is dominant or recessive

Different ways of studying genetics

1.) Genetic dissection

2.) Forward genetics

3.) Reverse genetics

Genetic dissection

1.) Produce mutants via irradiation (i.e. mutagens)

2.) Cross mutants with wild type to see if the offspring produce predictable phenotypic ratios

3.) Do this for a bunch of mutants for the trait in question

Forward genetics

Start with the phenotypic mutants and then look at the DNA sequence for differences, to see where the mutation is

Reverse genetics

1.) Start looking at DNA for candidate genes

2.) Then induce genetic changes (i.e. mutations) to see how it affects the phenotype