Genetics Definitions/Characteristics Flashcards
SNV
Single Nucleotide Variation–an individual’s genetic information has a point mutation in it
SNP
Single Nucleotide Polymorphism–a point mutation in a gene has been identified in a population
Types of Gene Variation
1) SNP/SNV
2) Insertions and deletions
3) Structural changes (inversions, translocations)
4) Copy number variations (gene duplication)
Types of Repetitive Element Variations
1) Tandem-adjacent
2) Interspersed repetitive elements
Types of Tandem-Adjacent variations and roles
1) Satellite (appear in telomeres, centromeres. 100+bp repeats)
2) Variable number repeats (micro/10-60), highly variable in population. Appears in forensics
3) Short tandem repeats (mini 2-10 bp), seem to be involved in gene expression
Types of interspersed elements
1) LINES
2) SINES
3) DNA transposons
4) Retroviral like transposons
Difference between a mutation and a polymorphism
Polymorphisms require about 1% of the population to be affected by a conditions. Mutations often affect the phenotype negatively.
Mechanisms of mutation
1) Loss of function (gene off)
2) Gain of function (gene can’t go off)
3) Acquisition of a property
4) Dominant negative (a negative damages normal gene product)
5) Ectopic function
Difference between a major and minor malformation
Major malformations have cosmetic, surgical, and medical effects.
Minor malformations may have cosmetic effects but are not indicative of an underlying condition.
Definition of a syndrome
A set of physical/mental manifestations that can be traced to one etiology
Definition of aneuploidy
A gain or loss of a chromosome
Causes of aneuploidy
1) Meiotic Nondisjunction (parental)
2) Mitotic Nondisjunction (mosaic)
Holoprosencephaly
Failure of the brain to bilobate
Balanced translocation
A reciprocal shift in genetic material from one location to another without a phenotypic effect
Robertsonian translocation
The fusion of two acrocentric chromosomes around a centromere
Locations where a centromere can be found
Metacentric–the middle of the chromosome
Submetacentric–near the middle of the chromosome
Acrocentric–near the end of the chromosome
Unbalanced translocation
An inherited shift in genetic material that induces a phenotypic effect in the offspring
Isochromosomes
Robertsonian translocations that occur with two copies of the same chromosome
Paracentric Inversion
Inversion of genetic information that happens on the same side of the centromere at the original copy
Pericentric inversion
Inversion of genetic information that happens on the opposite side of the centromere of the original copy
Types of Genetic Testing
- length of detectable DNA
- advantages/disadvantages
1) Karyotyping, can see up to 8000 MBP of DNA, measures largescale genomic changes, less specific for certain sequences
2) FISH can detect ranges of 100-300 kBP of DNA, measures deletions, duplications
3) CMA can detect ranges of 1-5 KBP of DNA or RNA, also can measure deletions and duplications, also can look at gene expressivity (if using RNA). Cannot look at rearrangements of DNA
Penetrance
The extent to which a dominant allele is expressed in a population
–If 100% penetrance, then condition considered completely penetrant
Mendel’s First Two Laws
1) Two members of a factor pair segregate independently
2) Factors for different traits segregate differently from one another (except linkage)
Characteristics of Autosomal Dominant Conditions
1) 1 mutant allele necessary to cause a change in a condition
2) Equally applies to both sexes
3) Affects multiple generations in a pedigree
4) The heterozygous person has a 50% recurrence risk
