Week 10 Flashcards
Define Genome
The full set of gens and noncoding regions
What are the four different components of a genome:
- Integrated Series
- Regulatory sequences
- Noncoding DNA
- Structural elements
What are the three use of molecular evolution?
- Study of mechanism and evolution of macromolecules
- Study of relationship between structures of genes and proteins
- Using molecular variations to reconstruct the evolutionary history
What are the three different types of change that can occur in a gene:
- Substitution
- Deletion
- Insertion
What are the 5 different types of substitution
1) Single Substitution
2) Multiple substitution
3) Parallel substitution
4) Coincident substitution
5) Back sostitution (reversion)
Describe multiple substitution:
More thant one change occured at a position between ancestral and at least one observed sequence
Describe coincident substitution:
At a given position, different substitutions occur between the ancestral and each observed sequence
Describe parallel substitution:
The same substitutions occured independently from ancestral and each observed sequence
Describe back substitution:
after a change at a given position, a second sobstitution change the gene back to its ancestral state
What are the two different types of substitution based on the sequence they produce?
- Synonimous substitution
- Nonsynonimous substitution
Substitution rate are higher at which kind of nucleotide?
A nucleotide position that don’t alter the aminoacid expression (Synonimous substitution)
Describe synonimous substitution:
Subsitutions that doesn’t change the sequence of encoded aminoacid.
Describe nonsynonimous substitution:
Substitutions that change the sequence of encoded aminoacids.
Describe the neutral theory of molecular evolution:
It states that the majority of mutations are neutral and accumulate through genetic drift.
Illustrate the three types of mutations and aminoacid replacement:
- Neutral
- Deleterious (Undergo puryfing selection)
- Beneficial (Undergo positive selection)
Describe what happen if an aminoacid replacement is neutral:
The rate of synonimous and nonsynonimous will be very similar (and thei ratio will be 1)
Describe what happens if an aminoacid replacement is under positive selection:
The rate of nonsynonimous substitutions will exceed the rate of synonimous substitution (the rate will be >1)
Describe what happen if an aminoacid replacement is under puryfing selection:
The rate of nonsynonimous substitutions will be lower than the rate for synonimous substitutions (the rate will be <1)
What are pseudogenes?
Duplicate copies of gene that are no longer functional
What’s transition?
A change between two purines or two pyrimidines
What’s transversion?
A change between purines and pyrimidines
Why do many nucleotide substitution have no effects on the protein encoded by a gene?
Because most amino acids are specified by more than one codon
What’s paralogs?
Genes found in the same or different species related through a gene duplication.
When do we use paralogs?
We use them when we’re interested in a change in function of the gene resulted from gene duplication.
What are orthologs?
Genes found in different species and that can be trace to a speciation event
When do we use orthologs?
When we want to reconstruct the evolutionary history of the species that contain the gene
