Lecture 15: What is genetics Flashcards
Mutant
An offspring of a normal member of the species but that is genetically different. The genetic difference is heritable
Strains/Variants
Organisms isolated from nature that are the same species but that have different properties
Genotype
Sequences of an organisms DNA. If 2 organisms have the same genotype, they’re genetically identical
Phenotype
Observable properties of an organism
Mutation
Any heritable change in DNA sequence. Damage or changes to DNA that are repaired or that are restore to original sequence are not mutations. Neither are reversible sequence changes, such as reversible DNA inversions
Allele
Different forms of the same gene, which share a high degree of sequence similarity as well as a common chromosomal location. If one form of a gene has a mutation and another has wild-type sequence, they are different alleles of the same gene
Homologs/Copies/Duplications
Similar genes in different chromosomal locations
Classical Genetic Approach
-Isolate individual organisms that are mutants, that contain alterations in the function you are studying
-Find out where the DNA mutations are in the chromosome
-Determine how many genes are involved in the function you are studying
-A gene is only known to exist because a mutation in it caused an observable change
Advantages of classical genetics
Mutants with an altered function can be isolated and characterized without requiring any prior knowledge of what molecules contribute to the function you are studying
Reverse Genetics
Clone a gene and then study and mutate it in order to investigate its function
Disadvantages of classical genetics
It may be difficult to figure out which mutations are most important. It may not be obvious why certain genes are involved in a phenotype
Molecular genetic techniques
DNA can be isolated and characterized. It can be manipulated to directly study the relationship between gene, macromolecule, and phenotype
Reverse genetics
Gene can be investigated without any direct knowledge of its function
Catabolic mutants
A mutant that can no longer use a particular substance for growth that can be used for wild-type
Auxotrophs
Mutants that have mutations in genes whose products are required to make an essential growth substance
Prototrophs
The original strain or a starin that can make the essential substance
Reversion
Process in which the mutation is restored to the original wild-type sequence
Suppression
The process of alleviating the effect of the original mutation in a second site
