CMP 2 - Genetics and Disease 1 0.0 / 5 ? BiologyCMPUniversityNone Created by: OwenBeesleyCreated on: 02-03-18 12:23 Types of germline defects: Chromosomal, Mitochondrial, Monogenic, Polygenic 1 of 48 Types of somatic defects: Cancer, Mosaics, Chimeras 2 of 48 What are chromosomal defects? Changes in chromosome number and structure, mostly not inherited 3 of 48 How are chromosomal defects inherited? Cytogenetic analysis 4 of 48 What is Euploidy? Abnormal haploid number of chromosomes (multiple of 23) 5 of 48 What are two examples of euploidy? Triploidy - 3n, Tetraploidy - 4n 6 of 48 What is Aneuploidy? Abnormal chromosome number 7 of 48 What are two examples of aneuploidy? Trisomy - (2n+1), Monosomy - (2n-1) 8 of 48 What is the process of cytogenetic analysis? 1) Centrifuge blood, 2) Treat with hypotonic solution, 3) Fix, 4) Stain, 5) Examine under microscope 9 of 48 What is the function of the hypotonic solution? To lyse the cells 10 of 48 What cells are generally used for cytogenetic analysis? WBC - easily accessible. But you can use any dividing cell 11 of 48 How does banding work? Addition of trypsin results in varying chromatin densities with addition of protease - unique structure 12 of 48 What is a picture of a chromosome set called? Karyogram 13 of 48 What is the complete set of chromosomes of an individual called? Karyotype 14 of 48 What is the telomere? The ends of a chromosome 15 of 48 What is the centromere? The middle of a chromosome 16 of 48 What is the p arm? The short (petit) arm 17 of 48 What is the q arm? The long arm 18 of 48 What is FISH? Fluorescence In Situ Hybridisation 19 of 48 How can FISH be used? For identification of a specific DNA region 20 of 48 What can FISH detect? Reciprocal translocations, DNA movement etc 21 of 48 What are the two mechanisms in which triploidy can occur? Diandry - Paternal. Digyny - Maternal 22 of 48 How does diandry occur? Two sperm/Diploid sperm fertilises egg - two sets of paternal chromosomes 23 of 48 How does digyny occur? Diploid ovum/ovum + polar body. Two sets of maternal chromosomes 24 of 48 What are imprinted genes? Genes that differ expression depending on parental origin 25 of 48 Example of an imprinted gene? IGF2 - Paternal copy produces, Maternal copy doesn't 26 of 48 What is an example of Aneuploidy? Down's syndrome 27 of 48 Genetic makeup of Down's syndrome? 2n+1 - Extra copy of chromosome 21 28 of 48 How is Down's syndrome caused? Non-disjunction in female meiosis 29 of 48 How does this occur? Both copies of chromosome 21 go to same daughter cell 30 of 48 Why does the risk of conceriving a child with Down's syndrome increase with age? Eggs are present in birth, are in prophase for decades, and can get damaged when aging occurs 31 of 48 Symptoms of Down's syndrome: Increased risk of leukemia, intelectual disability, increased infection risk etc 32 of 48 What are the 3 live-born aneuploidies: Trisomy 21, 13, 18 33 of 48 What is trisomy 21 known as: Down's syndrome 34 of 48 What is trisomy 13 known as: Patau 35 of 48 What is trisomy 18 known as: Edwards 36 of 48 What trisomies are most likely to allow survival? Mosaic/partial trisomies - not all cells contain abnormalities 37 of 48 How can trisomy correction work? Insert XIST in chr 21, induces Barr body in extrac chr 21, reduces transcription 38 of 48 What does XIST stand for? X-inactivation gene 39 of 48 What is Turner syndrome? XO female - only viable human monosomy 40 of 48 What is Klinefelter syndrome? XXY male - intellectual defects etc 41 of 48 What are the two types of translocations? Robertsonian, Reciprocal 42 of 48 What is robertsonian translocation? When acrocentric chromosomes combine 43 of 48 What is reciprocal translocation? More common, chromosome materials swap between non-homologous chromosomes 44 of 48 What is a deletion? When parts of a chromosome are removed 45 of 48 Egs of deletions? 5p- Cri-du-Chat, 4p- Wolf-Hirschhorn syndrome 46 of 48 Other possible chromosomal abnormalities? Inversions, ring chromosomes 47 of 48 What does UPD stand for? Uniparental disomy 48 of 48
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