Flashcards
Large Scale Chromosomal Aberrations
Flashcards do conjunto (15)
- 1What are the 3 types of chromosome mutations?Relocation
Loss of genetic material
Gain of genetic material - 2On chromosomes, which is the short arm and which is the long arm?Short - p arm
Long - q arm - 3What is aneupolidy?When the chromosome number differs from normal euploid (2n) cells by part of a chromosome set
- 4What are 3 types of aneuploidy?Monosomic (2n - 1)
Trisomic (2n + 1)
Nullosomic; lacking a single chromosome pair (2n - 2) - 5What are the 4 aneuploids of sex chromosomes? Give 2 examples of conditions that arise from aneuploidy.XXY - Klinefelter sydrome
XYY
XXX
XO - Turner syndrome - 6How does aneuploidy occur? Give detail of the process.Nondisjunction (when homologous chromosomes or sister chromatids fail to separate during nuclear division --> abnormal chromosomal distrib.)
- At first division:
Spindle fibres from a single pole attach to centromeres of both homologour chromosomes of a pair.
Frequent if no crossing over occurs
- At second division:
Spindle fibres from a single pole attach to centromeres of both sister chromatids
Sister chromatids move to same pole
Can be lethal to embryo - 7Give 3 examples of autosomal trisomy and where they occurDown syndrome - 3 copies of chromosome 21 (increased incidence as maternal age increases)
Patau syndrome (trisomy 13)
Edwards syndrome (trisomy 18) - 8What are the 4 types of structural variation of the chromosome?1. Deletions
2. Duplications
3. Inversions
- Pericentric inversion: on one side of centromere
- Paracentric inversion - regions change places
4. Translocations
- Reciprocal - swap
- Nonreciprocal - 9WHY does structural variation of the chromosome occur?- Errors (e.g. deletions) occur when rejoining broken chromosome segments
- Improper crossing over (NAHR - non-allelic homologous recombination) - 10Give an example for each type of structural variation: deletions and duplicationsDeletion:
- Cri-du-chat/5p syndrome (part of short arm of chromosome 5. 1 in 50,000 births)
Duplication:
- Cat eye syndrome (rearrangements of chromosome 22)
- Rearrangement included inverted duplication spanning p to q11.2 - 11HOW do structural chromosome variations occur?- Spontaneous in gonads of parents with otherwise normal chromosomes
- Recombination in a parent w/ heterozygous reciprocal - 12How do robertsonian translocations in Down's syndrome occur? What is the frequency of this?- Breakage in chromosome causes fusing b/w chromosomes 14 and 21
- Trivalent formation in meiotic pairing
- 2 normal copies of chromosome 21, 1 of chrom. 14, 1 21-14 fusion
- 3% of Down's syndrome cases - 13What is the definition of a karyotype?The number and appearance of the chromosomes
- 14What are 2 types of variation in the human karyotype?Variation in chromosome number
Variation in chromosome structure - 15What is the cause of age-related nondisjunction?- Human meiocytes are arrested at diplotene (P1) before birth
- Chiasmata hold sister chroms. (bivalents) together and must remain intact until meiosis resumes during menstrual cycle
- As time passes, chance of bivalent breakdown increases
- Most nondisjunction occurs at Anaphase 1
Informações
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- Year 1 BIO154 - Genetics I FlashCards sobre Large Scale Chromosomal Aberrations, criado por Sophie Byrne em 17-04-2018.
- Criado por
- Sophie Byrne · abr 2018
- Atualizado
- 18 abr 2018
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