MUTATION Flashcards
defined as a heritable alteration or change in the genetic material
MUTATION
drive evolution but can also be pathogenic
MUTATION
Sequence variants with no obvious effect upon phenotype
POLYMORPHISM
may cause adult-onset disease, such as cancer, but cannot be transmitted to offspring.
SOMATIC MUTATION
can be transmitted to future generations unless it affects fertility or survival into adulthood
GAMETE
It is estimated that each individual carries up to _____________ alleles that in the homozygous state would have very
serious effects.
SIX LETHAL
what are the types of mutation
SUBSTITUTION
DELETION
INSERTION
replacement of a single nucleotide by another
SUBSTITUTION
the most common type of mutation
SUBSTITUTION
If the substitution involves replacement by the same type of nucleotide
TRANSITION
Substitution of a pyrimidine by a purine or vice versa
TRANSVERSION
involves the loss of one or more nucleotides
DELETION
the addition of one or more nucleotides into a gene
INSERTION
If a mutation does not alter the polypeptide product of the gene
SYNONYMOUS
are observed to occur less frequently than synonymous mutations
NON SYNONYMOUS
If a mutation leads to an alteration in the encoded polypeptide
NON SYNONYMOUS
single base-pair substitution can result in coding for a different amino acid and the
synthesis of an altered protein
MISSENSE
If the mutation codes for an amino acid that is
chemically dissimilar, the structure of the protein will be altered and can lead to a gross
reduction, or even a complete loss, of biological activity
NON CONSERVATIVE SUBSTITUTION
result in the replacement of a different amino acid that is chemically similar, and may have no functional effect, it retains its normal biological activity
CONSERVATIVE SUBSTITUTION
substitution that leads to the generation of one of the stop codons will result in
premature termination of translation of a peptide chain
NONSENSE
substitution that leads to the generation of one of the stop codons will result in
premature termination of translation of a peptide chain
NONSENSE MEDIATED DECAY
If a mutation involves the insertion or deletion of nucleotides that are not a multiple of three, it will disrupt the reading frame and constitute
FRAMESHIFT
DNA are less likely to have a phenotypic effect
MUTATION IN NONCODING DNA
Mutations of the highly conserved splice donor (GT) and splice acceptor (AG) sites.
aberrant splicing
which resemble the sequence of an authentic splice site, may be activated when the conserved splice sites are mutated.
Cryptic splice sites
reduced activity or of decreased stability of the gene product
HYPOMORPH
complete loss of the gene product.
AMORPH
Loss-of-function mutations in the heterozygous state in which half normal levels of the gene product result in phenotypic effects
HAPLOINSUFFICIENCY
esult in either increased levels of gene expression or the development of a new
function(s) of the gene product
Gain-of-Function Mutations
Mutations that alter the timing or tissue specificity of the expression of a gene can also be considered
Gain-of-Function Mutations
are dominantly inherited and the rare instances of gain-of-function mutations occurring in the homozygous state are often associated with a much more severe phenotype
Gain-of-Function Mutations
example of prenatally lethal disorder
HOMOZYGOUS ACHONDROPLASIA OR WAARDENBURG SYNDROME TYPE1
is one in which a mutant gene in the heterozygous state results in the loss of protein activity or function
DOMINANT-NEGATIVE MUTATION
are particularly common in proteins that are dimers or multimers, for instance structural proteins such as the collagens
DOMINANT-NEGATIVE MUTATION
are particularly common in proteins that are dimers or multimers, for instance structural proteins such as the collagens, mutations in which can lead to ______________
OSTEOGENESIS IMPERFACTA
Developments in molecular genetics increasingly allow identification of the mutational basis of the specific features that occur in a person with a particular inherited disease
PHENOTYPE
This has resulted in attempts to correlate the presence of a particular mutation
GENOTYPE
with the specific features
seen in a person with an inherited disorder, this being referred to as
GENOTYPE-PHENOTYPE CORRELAION
Naturally occurring mutations are referred to as
SPONTANEOUS MUTATIONS
Environmental agents that cause mutations are known as
MUTAGENS
Includes electromagnetic waves of very short wavelength (x-rays and γ
rays) and high-energy particles (α particles, β particles, and neutrons).
RADIATION
the measurement of radiation.
DOSIMETRY
include cosmic rays, external radiation from radioactive materials in certain rocks, and internal radiation from radioactive materials in tissues.
Natural sources of radiation
diagnostic and therapeutic radiology, occupational exposure and
fallout from nuclear explosions.
Artificial sources of radiation
may be more important than radiation in producing genetic damage.
chemical mutagens
Mutations in at least eight of the genes encoding these proteins can cause
xeroderma pigmentosum
characterized by extreme sensitivity to ultraviolet light and a high frequency of
skin cancer.
xeroderma pigmentosum
