Clear and orderly summary of Chapter 19 of the book "Genetics: Analysis and Principles, 6th Edition by Robert Brooker". Together with all my other summaries of Genetics I got an 8,5 for this course.
Genetics Summary Chapter 19 – Gene mutation and DNA repair
Mutation; permanent (heritable) change in genetic material essential for continuity
of life natural selection
19.1 Effects of mutation on gene structure and function
Gene mutation
Point mutation; change in single base pair. By substitution (vervangen) base for
another.
- Transition; change pyrimidine to another pyrimidine OR purine to another
purine
- Transversion; change purine to pyrimidine or pyrimidine to purine.
Additional/deletion
Gene mutation alter (wijzingen) the coding sequence (molecular effects of mutation)
Effects of point mutations
- Silent mutations; does not alter the amino acid sequence
- Missense mutations; does alter the amino acid sequence
o Neutral mutation; when missense mutation has no effect on protein
function.
- Nonsense mutations; does change from a normal codon to stop codon
Effects on addition/deletion mutations
- Frameshift mutations; does shift the reading frame of codons by deletion or
addition.
Mutation in non-coding regions; affect gene expression
Non-coding regions; promotor, regulatory elements, operator site, UTRs and splice
recognition sequence.
Up promotor mutations; mutation in promotor that increase rate of transcription
Down promotor mutations; mutation in promotor that inhibits the rate of transcription
Effects of mutation to wild-type genotype and phenotype
- Wild type genotype
Wild-type; prevalent (heersend) genotype in natural population
Mutant allele; allele that is created by altering a wild-type allele by mutation
Reversion; mutation that returns mutant allele back to wild-type allele
- Wild type phenotype
Deleterious mutation; decreases (minder worden) the change of survival and
reproduction. It is harmful with regard to its effect on phenotype
Lethal mutation; results in death.
Benefiial mutation; enhances the change of survival and reproduction
Conditional mutants; phenotype depends on environmental conditions. Phenotype is
affected only under a defined set of conditions.
Suppressor mutations
Second mutation affect the phenotypic expression of first mutation.
Suppressors (mutations); it suppresses the phenotypic effects of another mutation
, - Intragenic; suppressor is in the
same gene as the first
mutation that is suppressed
- Intergenic; suppressor is in a
different gene from the first
mutation that is suppressed.
o Redundant (overtollig)
factor; suppressor
alters the structure of
the second protein so it
can take over the
functional role of the
defective protein
o Common pathway;
suppressor alter the
function of second
protein
o Multimeric protein;
suppressor mutates a
subunit so it is active
o Transcriptional factor;
suppressor occur in
gene that encodes
transcription factor. It
activates another gene.
Change in chromosome structure
Breakpoint effect; region where two chromosomes break and rejoin with other
chromosome species. This has effect on gene function.
Position effect; the location of gene is changed from one chromosomal site to a
different one. This has effect on gene expression.
Explanations for this effect;
- Inversion
- Translocation gene becomes inactive.
Mutations can occur in Germ-Line or Somatic cells
Cells of animals two types;
- Germ-line; cells that give rise to the games (egss and
sperm).
Germ-line mutation, occur directly in sperm or egg
cell or in precursor cell that produces the gametes
- Somatic cells; all the cells exclude germ-line
Somatic mutation; occur in single embryonic cell.
Genetic mosaic; person that has somatic regions that differ
genotypically form each other.
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