Variation chromosome structure & number 4 Flashcards
What are the types of chromosome mutations?
- Deletion
- Duplication
- Inversions
- Translocation
Deletion
Segment of chromosomal material is missing (deficiency is the term used to describe a missing region of a chromosome)
Duplication
Section of a chromosome is repeated more than once within the chromosome
Inversion
Involves a change in the direction of the genetic material along a single chromosome
Translocation
Occurs when one segment of a chromosome becomes attached to a different chromosome or to a different part of the same chromosome
Simple Translocation
Occurs when a single piece of chromosome is attached to another chromosome (1-way transfer)
Reciprocal translocation
Two different chromosomes exchange pieces, thereby altering both of them (2-way transfer)
________ & _________ are changes in the total amount of genetic material in a single chromosome
Duplication & deletions
_________ & ________ are chromosomal rearrangements
Inversions & translocation
Deletion you _______ genetic material & duplication you ______ genetic material
Lose, gain
Loss of genetic material due to deletion tends to be ________ to an individual phenotype
Harmful
A chromosomal _______ occurs when a chromosome breaks in one or more places & a fragment of the chromosome is lost & degraded
Deletion
_________ can also occur when recombination takes place at the wrong spot between two homologous chromosomes where the product is one chromosome has deletion & other has duplication
Deletion
The phenotype consequences of deletions depends on the __________ and whether or not essential genes were lost (which would be most harmful)
Size deleted
__________ syndrome is a result of deletion in the short arm in chromosome 5
Cri-du-chat syndrome
Terminal deletion
When an end piece is deleted
Interstitials(internal) deletion
Occurs when 2 places in between is lost
__________ can created a new gene
Interstitial deletion
_________ tends to have less harmful phenotype consequences than deletions
Duplication
_________ results in extra genetic material
Duplication
Repetitive sequences
Sequences that occur multiple times
Nonallelic homologous recombination
When a crossover occurs at homologous sites (repetitive sequences) but the site is not alleles of the same gene
____________ results in one chromatid having an internal duplication & the other chromatid has a deletion
Nonallelic homologous recombination
Gene duplication
Occurs when a gene increase in number like when there two C genes on a chromosome
The phenotype consequences of duplication depends on the _________ duplicated whereas its likely to have an effect on the phenotype if large amounts are duplicated & has bad recombination
Amount
____________ disease is a result of duplication in the short arm of chromosome 17
Chariot- marie tooth disease
_____________ usually don’t result in phenotype consequence
Inversion
A chromosome with an _______ contains a segment that has been flipped so it runs in the opposite direction
Inversion
Inversion are classified by the location of the _________
Centromere
Pericentric inversion
If the centromere is within the inverted region of the chromosome
Paracentric inversion
If the centromere is found outside the inverted region
When a chromosome goes through ________ the total amount of genetic material is the same (why it doesn’t have phenotype consequences)
Inversion
Position Effect
Is a change in phenotype that occurs when the position of a gene changes from one location to another (cause by inversion)
The position effect results in a change of ___________
Gene expression
Translocation
Involves exchange between different chromosomes
__________ is when a piece from one chromosome is attached to another chromosome
Translocation
Translocation also involves ______________ where DNA breaks & a bad repair is resulted (has bad crossing over & non homologous)
Two break (2 - way transfer)
Reciprocal translocation
When two nonhomologous chromosomes cross over
________ & _______ change the number of chromosomes
Aneuploidy & Euploidy
Aneuploidy
Change the number of specific chromosomes
Euploidy
Change in the number of complete sets of chromosomes
If an euploid variation occurred it will end in ______
“ploid” (ex. triploid, tetraploid)
If an aneuploidy variation occurred then it will end in _______
“somy” (ex. trisomy (2n+1), monosomy (2n-1))
____________ causes an imbalance in gene expression which can have harmful consequences on the phenotype
Aneuploidy
What are the most common trisomies?
Trisomy in chromosome 13, 18, 21
Aneuploidy & euploidy occurs during _______ by congenital where 50% of miscarriage occur & low survival rate at birth
Meiosis ( 1 or 2)
Aneuploidy of _______ is less serve due to X-inactivation the extra X-chromosome is turned off
Sex chromosome
______________ in chromosome are influenced by the age of the parents(mostly the female) where the older the parents (mostly the mom) is more likely to produce children with abnormalities in chromosome number (ex. down syndrome)
Human abnormalities
Down syndrome is due to _________
Trisomy 21 (3 chromosomes in chromosome number 21)
Down syndrome has 15x chance of ________
Leukemia
_________/________ in older women trying to have kids may be benetifical because the body may not be ready or maybe be risky for the mother & child
Aneuploidy/ Miscarriage
Down syndrome is cause by ____________ in chromosome 21 during meiosis 1
Nondisjunction
What is another explanation of down syndrome?
That the female egg are the rest in prophase of meiosis 1 for a long time & the extra time may be contributing to an increased frequency in nondisjunction
Diploid animals are ______ & if the number of chromosomes is greater than 2n than its polyploid & can be lethal (exception are female bees (diploid 2n) & male bees (monoploid 1n)
2n
There is 8n cells in the liver because why?
They have detoxification proteins
Nondisjunction
Chromosomes don’t segregate properly
Meiotic nondisjunction
Can produce cells that have too many or too few chromosomes
Nondisjunction happens in meiosis at ___________
Anaphase 1 or 2
Nondisjunction in meiosis 1 yields _____ bad haploid cells & nondisjunction in meiosis 2 yields _____ bad haploid cells (Aneuploidy)
4, 2
Complete nondisjunction
When all of the chromosomes undergo nondisjunction & move to one of the daughter cell where the results is a diploid cell & a cell without any chromosomes (euploidy)
