Lecture 4 Flashcards
What is the definition of a gene?
A piece of DNA that is transcribed to make RNA
What are the laws of inheritance?
- Segregation 2. Recombination
What is the definition of segregation?
The segregation of alleles at the same locus into different gametes during gamete formation
What is the definition of recombination?
The production of combinatorial, genetic variation
What are 2 ways to produce recombination?
- Independent assortment of chromosomes
- Crossing over
What is the definition of independent assortment of chromosomes?
Describes how alleles of 2 different genes get sorted into gametes independently of each other; combinations of different chromosomes
What is the definition of crossing over?
The exchange of genes between homologous chromosomes, resulting in a mixture of parental characteristics in offspring; combinations of different genes on the same chromosome
What is an advantage of recombination?
New gene combinations are created, increasing genetic diversity
What is a disadvantage of recombination?
Co-adapted gene combinations are broken up
What is the definition of a mutation?
An error in the replication of nucleotide sequences; any other alteration of the genome that is not manifested as recombination
Are mutations random?
While mutations are NOT truly random (laws govern mutational changes), they are UNDIRECTED with respect to a particular goal/organism need/environmental favors
What is the definition of a transition?
A mutational change from a purine to a purine, or a pyridimine to a pyridimine
What is the definition of a transversion?
A mutational change from a purine to a pyrimidine, or a pyridimine to a purine
Which mutational change in bases occurs more frequently?
Transitions occur more frequently than transversions, because transversions involve different chemical types
How do mutation rates differ?
- Between organisms
- Between genes of the same organism
What is the ultimate source of ALL variation important to evolution?
Mutations
What are the 4 evolutionary forces?
- Mutation (changes allele frequencies in a population)
- Selection
- Genetic drift
- Migration
What is the definition of a synonymous mutation?
Substitutions which do not cause a change in the amino acid (i.e. silent mutations)
What is the definition of a non-synonymous mutation?
Substitutions which cause the amino acid to change
What are the different types of gene mutations?
- Nucleotide substitutions
- Insertions/deletions
What are the different types of chromosome and karyotype alterations?
- Inversions/duplications/translocations
- Chromosome fusion/fission
- Polyploidization
What is the definition of a karyotype?
The chromosome complement of an individual
What is the definition of an inversion?
A 180 degree reversal of the orientation of a part of a chromosome relative to some standard chromosome
What is the definition of gene duplication?
The production of 1+ copies of a gene as a result of unequal crossing over
What can duplicated genes evolve into?
- Pseudogenes (degraded, nonfunctional genes)
- Unaltered, repeat-copy
- Genes with new function
What is the definition of chromosomal translocation?
The shuffling of chromosomal fragments between nonhomologous sites
What is the definition of chromosomal fusion?
The fusion of 2 chromosomes to form 1
What is the definition of chromosomal fission?
The splitting of 1 chromosome into 2 smaller chromosomes
What is the definition of polyploidy?
The having of more than 2 sets of chromosomes (e.g. tetraploidy)
What are the different types of external sources of genetic variation?
- Hybridization/introgression
- Lateral gene transfer
What is the definition of hybridization?
The process of producing a hybrid by mating 2 parents form different varieties/species in which descendant phenotypes can be novel
What is the definition of horizontal (lateral) gene transfer?
The movement of genetic material between distantly related organisms other than by (“vertical”) transmission of DNA from parents to offspring (i.e. reproduction)
What is FST - analysis (fixation index) used for?
Scaled 0-1, where 0 means genetically identical and 1 means genertically dissimilar
What is the definition of introgression?
The transfer of genetic information from 1 species to another as a result of hybridization and repeated backcrossing
