Genetics - Chromosomes and Cell Division Flashcards
How is a chromosome recognised?
Banding pattern with specific stains, length and position of centromere. Slide 8
What are the parts of the chromosome?
Telomere - the end
Short arm (p) - above the centromere
Centromere
Long arm (q) - below the centromere. Slide 8
What are telomeres for?
Protection and replication. Slide 8
What are acrocentric chromosomes?
Where the short arm doesn’t really matter as it may be really small so it codes for satellite ribosomal genes e.g. tRNAs. Slide 9
What are the two types of chromosome rearrangement?
Balanced and unbalanced. Slide 11
What is the difference between balanced and unbalanced?
In balanced all the chromosomal material is present, in unbalanced there is either extra or missing chromosomal material. Slide 11
Why must you understand conventional cytogenetics?
It is essential to interpret modern genetic analysis using molecular techniques. Slide 12
What does aneuploidy mean?
Whole extra or missing chromosome. Slide 13
What does translocation mean?
Rearrangement of chromosomes. Slide 13
What does insertion and deletion mean?
Missing or duplicated genetic material. Slide 13
What causes down syndrome?
3 chromosomes 21. Slide 14
What is Robertsonian Translocation?
When two acrocentric chromosomes are stuck end to end (small p arms). Slide 17
Why is X chromosome aneuploidy better tolerated than down syndrome?
Due to X inactivation. Slide 22
What is reciprocal translocation?
When two chromosome parts swap so it is balanced. However there is a reproductive risk. Slide 24
What can unbalanced reproductive products result in?
Miscarriage or dysmorphic delayed child. Slide 31
How does FISH work?
Allows one specific genetic area to be targeted. Slide 34
What are two molecular techniques to see cytogenetics?
Array Comparative Genomic Hybridisation (aCGH) and Quantitative PCR. Slide 38
What does microarray CGH do?
Detects any missing/duplicated piece of chromosome but many changes seen are neutral DNA polymorphisms. Slide 39
What is mosaicism?
When different cells have a different genetic constitution. You acquire mutations are cells develop. Slide 44+46
What does the aCGH not capable of?
Doesn’t detect balanced rearrangements. Slide 54
