Chromosomal Mutations Flashcards
(33 cards)
What are the major types of chromosomal rearrangements? (5)
DDITT
deletions duplications inversions translocation transpositions
DELETIONS
What are chromosomal deletions?
Chromosomal deletions involve deletion of more than one gene.
Drosophila geneticists refer to deletions as ______ and use the abbreviation ____.
Drosophila geneticists refer to deletions as deficiencies and use the abbreviation Df.
DELETIONS
What are causes of deletions?
- Incorrect repair of broken DNA
- incorrect reciprocal genetic exchange
- secondary consequences of chromosomal rearrangements
DELETIONS
Chromosomal deletions also can occur from faulty meiotic crossing over, if the reciprocal exchange is __________.
Chromosomal deletions also can occur from faulty meiotic crossing over, if the reciprocal exchange is NOT reciprocal.
DELETIONS
What are interstitial deletions?
Deletions that are in the interior.
DELETIONS
Deletions can be _____ or _____.
Deletions can be terminal or interstitial.
DELETIONS
All stable deletions are _______.
All stable deletions are interstitial with at least the telomere on the other side.
DELETIONS
T or F: Different organisms tolerate deletions (deficiencies) to the same extent.
Different organisms tolerate deletions (deficiencies) to different extents.
In general, the more sophisticated the body of the adult, the MORE tolerant is the species of deletions (and duplications).
DELETIONS
In general, the more sophisticated the body of the adult, the _____ tolerant is the species of deletions (and duplications).
In general, the more sophisticated the body of the adult, the MORE tolerant is the species of deletions (and duplications).
DELETIONS
Between higher animals (vertabrates) and lower animals and plants, which tolerates deletions well?
Lower animals and plants tolerate deletions better than higher animals.
DELETIONS
In general, the bigger the deletion, the more ______ the consequence.
In general, the bigger the deletion, the more serious the consequence.
DELETIONS
Under what circumstance would a deletion homozygote survive?
In rare cases, when the deleted sequence contains no essential genes, a deletion homozygote may survive.
DELETIONS
Most of the time, homozygosity for a deletion (Del/Del) is _____ in all eukaryotes.
Most of the time, homozygosity for a deletion (Del/Del) is LETHAL in all eukaryotes.
DELETIONS
Individuals who are heterozygous for chromosomal deletion are essentially _____ for deleted genes.
Individuals who are heterozygous for chromosomal deletion are essentially hemizygous for deleted genes.
DELETIONS
What are the consequences of hemizygosity for deletions?
Phenotype problems/consequences
DELETIONS
The only way a diploid organism can survive a deletion of essential genes is if _____
The only way a diploid organism can survive a deletion of essential genes is if it carries a non-deleted wild type version on the homologous chromosome
*still can’t be too large deletion in heterozygote Del/+ (otherwise, lethal)
DELETIONS
What is pseudo-dominance?
Pseudo-dominance is the unmasking of a recessive mutation
*Can be used to map genes that are v close together
DELETIONS
What are some examples of humans who are heterozygous for chromosomal deletions?
- Cri du chat syndrome (cat-like cry in infants) due to deletion in chrosome 5
- microencephaly (small head)
- moon-like face
- mental retardation
- DeGeorge’s syndrome - a genetic disease that accounts for 5% of congenital heart defects
DUPLICATIONS
Duplications are symbolized by ____.
Duplications are symbolized by Dp.
DUPLICATIONS
What is a chromosome duplication?
Chromosome duplications - an extra copy of a region of a chromosome is present.
DUPLICATIONS
How are duplications generated?
Same reasons as deletions:
- incorrect repair of double strand breaks in the DNA
- errors during meiosis for crossing over
- duplications created as a secondary consequence of chromosome rearrangements
Which is usually more damaging: deletions or duplications?
Deletions are more damaging that duplications, but duplications still have negative effects.
DUPLICATIONS
Small duplications do not have strong negative effects. There is then an extra, non-essential copy of the gene. If this extra copy does not have a negative effect on the organism, it often persists.
What is an example of a the evolutionary impact of gene duplication?
Vision proteins are a good example.
