Variation chromosome structure & number Flashcards
Allelic Variation
Variation in specific genes
A reference point is used to determine what is __________ & ____________
Normal & abnormal (Ex. A normal person has 23 sets of pair of chromosomes so 46 chromosomes in total)
To classify & identify chromosomes scientist look at what?
- Centromere
- Size
- Banding patterns that are revealed when chromsomes are stained
Metacentric
The centromere is near the middle
Submetacentric
The centromere is slightly off the center
Aerocentric
The centromere is significantly off the center but not at the end
Telocentric
The centromere is at one end
Karyotype
Photo of organized chromosomes
Since chromosomes aren’t directly connected at the center one will be a _______ arm noticed by the letter p & a _______ noticed by the letter q
Long arm, short arm
In a karyotype the longest chromsomes have the ________ numbers & the smallest chromosomes have the ________ numbers
Lowest (like 1,2,3), largest (like 20, 21)
What are the types of mutations to affect/ rearrange genetic material in eukaryotic chromosomes?
- Deletions
- Duplications
- Inversions
- Translocation
Deletion
A segment of chromosomal material is missing (deleted) (deficiency- describes the missing (deleted) region)
Duplication
Section of a chromosome is repeated (duplicated) more than once in the chromsome
Inversion
Involves a change in the direction of the genetic material along a single chromosome
Translocation
Occurs when one segement of a chromosome becomes attatched to a different chromosome or to a different part of the same chromosome
Simple Translocation
When a single piece of chromsome is attatched to another chromosome
Reciprocal Translocation
Two different chromsomes exchange peices which alters both of them
____________ &___________ changes the total amount of genetic material in a chromosome
Deletion & duplication
_____________ & __________ are chromosomal rearrangments
Inversion & translocation
Loss of genetic material due to a deletion tends to be ____________ to an organism
Detrimental
____________ happens when a chromsome breaks in one or more places & the resulting fragments are lost
Deletion
Interstital deletion
When two fragments reconnect
____________ has a detrimental phenotype effect where larger deletions tend to be more harmful since more genetic materiall is missing (ex. Cri-du- chat sydrome)
Deletion
___________ tend to be less harmful than deletions because it results in extra genetic material
Duplications
Reptetive sequences
Segments of DNA that have idnetical or similar sequences
Nonallelic homologous recombinations
Crossover that has occural at repetitive sequences (homologous sites) but the sites are not the same version (allele) of the same gene (results may be on pair of the chromosome ebing duplicated 7 the other deleted)
__________ will affect the phenotype if its a large amount that was duplicated (Ex. CHarot -marie-tooth disease)
Duplication
____________ provides additional material for gene evolution sometimes leading to the formation of gene families
Duplication
Homologous genes
Two or more genes are dervived froma single ancestral gene
Paralogs genes
Homologous genes with a single species
Copy number variation (CNV)
Common among memebers of the same species
Inversion often occurs without ____________ consequences
Phenotype
A chromosome with an __________ contains a sgement that has been flipped so that it runs in the opposite direction (Inversion si classified based on the location of the centromere)
Inversion
If the centromere is within the inverted region of the chromosomes then that region is called what?
Pericentric inversion
If the cetromere is found outside the inverted region then that inverted region is called what?
Paracentric inversion
______________ may produce abnormal chromosomes due to crossing over
Inversion heterozygotes
Dicentric chromosomes
Dicentric bridge
Region connecting the centromere in dicentric chromosomes
Acentric fragment
Piece of chromosomes without any chromosomes
Balanced translocation
The total amount of genetric material us unchanged
___________ & ___________ ususally dont have phenotypic consequences
Inversion & translocation (&balances translocation)
Unbalanced translocation
Portions of genetic material are duplicated and/or deleted (results in phenotypic consequences) (ex. Robertsonian translocation)
Individuals with ________________ may produce abnormal gametes (offspring) due to the pairing & segregation of chromosomes
Individuals with _____________ can produce offsprings with unbalanced translocation
Balanced translocation
Euploid
Have a chromosomes number that is an exact multiple of a chromosome (Ex. A fruit fly has 8 chromosomes (2 sets of 4)) (8 divided by 4 = 2 exact sets)
Aneuploid
Alteration in the number of particular chromosomes so the total number of chromsomes is not an exact multiple of a set (Ex. A fruit fly with 9 chromosomes has 3 copies of chromosomes)
_______________ is an abnormal condition that has negative effect on the phenotype
Aneuploidy
______________ causes an imbalanced in gene expression that is often determined to the phenotype of the individual
Aneuploidy
_____________ in human causes detrimental phenotypes
Aneuploidy
Nondisjunction
Chromosomes dont segregate properly
Meiotic nondisjunction
Can produce cells that have too many or two few chromosomes
Mitotic nondisjunction
A patch of tissue in an organism is formed that has an attered chromosomes number
Meiotic nondisjunction can produce _________ or ______________
Aneuploidy or polyploidy
Mitotic nondisjunction or chromosomes loss can produce a patch of tissue with an altered ________________
Chromosome number
Changes in euploidy occur how ?
By:
- Autopolyploidy
- Alloploidy
- Allopolyploidy
Autopolyploid
Individual with one or more extra set of chromosomes
Alloploidy
An allploid has one set of chromosomes from two different species that are called allodiploid
Allopolyploid
Contains two or more sets of chromosomes from two or more species
