Inheritence and Mandelian Genetics - Genetics 1 & 2 Flashcards
Genetic Diversity
Variation in genetic traits within a population.
Why is genetic diversity essential for evolution?
In order for traits to be selected for, genetic diversity is needed (different combinations of alleles).
Mutation
Change in bases of DNA sequence affecting genetic information - including functional and non-functional genes.
Karyotypic Changes
Alterations in chromosome structure or number.
Evolution
Process by which species adapt over time.
DNA Replication
Process of copying DNA before cell division.
Polymerases
Enzymes that synthesize DNA strands.
How is erorr rate reduced in the DNA sequence during replication
Proofreading and mismatch repair
Proofreading
Error-checking mechanism during DNA synthesis in proofreading domains of polymerases
Mismatch Repair
Correction of base-pairing errors in DNA.
Base-Excision Repair
Repair mechanism for oxidative DNA damage.
How else can mutations occur apart from random changes to neucleotides?
DNA Damage. Agents causing mutatations (mutagens) cause their accumulation
Why do we use harmful chemicals
They havn’t been discovered yet as a mutagen/carcinogen
Deleterious
Negative, causing harm
Why do organisms have fine-tined mutation rates
- Too many mutations would be deleterious
- Mutations generate genetic diversity on which evolution acts
Successful organisms have evolved to repair their DNA efficiently, leaving just enough genetic variability for evolution to continue.
Transition Mutation
E.g. C - T
Substitution of one purine for another purine.
Transversion Mutation
E.g T - G
Substitution of a purine for a pyrimidine.
3 types of substitution mutations
- Silent
- Nonsense
- Missence
Missense Mutation
Single base change alters amino acid in protein.
Silent mutation
No effect because of the degenerate nature of amino acids
Why are missence mutations sometimes managable
R groups of the different amino acid being coded for can have the same charge/polarity (properties) so the 3D structure it folds to is similar enough to carry out its function.
Frameshift Mutation
Insertion or deletion alters reading frame of DNA. Every subsequent codon is changed and is are each/most amino acids coded for in the final protein. Protein is unable to bind so unexpressed