Chromosomes and Chromosomal Abnormalities Flashcards

Question

FISH

Answer 1

hybridization using a probe with a complimentary sequence to chromosome you care about easier to do after baby is born

Answer 2

each spot represents a unique part of the genome normal reference- green fetal- red isolate DNA from each sample label DNA with fluorescent tags Mix samples and hybridize to the microarray Rinse away unbound material; scan with a laser microscope ~comparing relative quantities ~this lets you scan the entire genome at once and look for changes in copy number

Answer 3

> 7-10 million bp Detects copy number variation and positioning

Answer 4

Edwards syndrome clench fist rocker bottom left foot low set, malformed ears mental retardation and cardiac malformations only 5% survive birth, only 10% of those live past 2 years

Answer 5

Patau Syndrome Bilateral cleft lip Polydactyl midline defects heart, nervous system, growth malformations

Answer 6

Downs Syndrome 1 in 800 Hypotonia- low muscle tone Short stature open mouth with large tongue Leukemia risk/ AD early onset

Answer 7

46, XY, t(14;21), +21 46, XY, -14, t(14;21) -as long as you have 2 copies of each you can by asymptomatic but at risk of passing it to child

Answer 8

Robertsonian Trisomy 21

Answer 9

Males only have 1 X chromosome and females have 2....body tried to make it so that the double X acts like a single X --> leads to x inactivation in mammals

Answer 10

Doesn't matter how many X always shutting it down so if female has 3 X, 2 are shut down if make has 2 X, 1 is shut down

Answer 11

some genes that are still expressed in an inactivated X chromosome (mainly a part of the p section of the chromosome) clincal phenotype is generally milder

Answer 12

Turner Syndrome ``` Diagnosis at birth or puberty Webbed neck Short stature lymph edema amenhorrea- absence of period infertility normal intelligence ```

Answer 13

Klinefelter Syndrome 2nd X goes thru X-inactivation but still some phenotype is expressed Infertility Hypogonadism Gynecomastia- male breasts Behavioral difficulties: learning, social, IQ

Answer 14

pArA: an inversion that is away from centromere *Inversions usually do not cause any abnormalities in carriers as long as the rearrangement is balanced with no extra or missing DNA

Answer 15

perI- inversion includes chromosome

Answer 16

Paracentric: Unbalanced offspring and genome instability ^chromosome has 2 centromeres and if spindle tries attaching at 2 spots, can rip the chromosome Pericentric: Unbalanced offspring

Answer 17

Individual probe sets labelled in 24 different colors for each unique chromosome Makes it easier to determine origin of any extra DNA Especially useful to look for translocations..normal abnormalities would be obvious in normal G-banded karyotype only use if expect substantial changes in # and structure

Answer 18

2 parts are swapped--> balanced translocation (# is still the same) vast number are not going to create a fusion protein --> worry is at meiosis how will they be passed on

Answer 19

ie of reciprocal translocation the t(9;22) gene acts like a kinase at the wrong times and places --> causes leukemia 46,XX, t(9;22)(q34;q11)

Answer 20

1) normally choice of Xi is random | 2) choice may become non-random if one of the X chromosomes is severely defected in some way

Answer 21

1) try to preserve the activity of one X equivalent | 2) (if possible) preserve autosomal sequences

Answer 22

isochromosome- either 2 p arms or 2 q arms on the same chromosome thru deletion --> crossing over --> ring

Answer 23

45, XO = 46, XX, i(Xq)

Answer 24

Cri du chat cry that sounds like a cat mental retardation microcephaly- abnormal head

Answer 25

Stains show compaction *there are different bands/stains per stage (ie: prophase has a lot)

Answer 26

Imaging chromosomal banding pattern

Answer 27

gene poor | heterochromatin

Answer 28

gene rich- 50+ genes per band | euchromatin

Answer 29

1) Size 2) Centromere position 3) Banding pattern

Answer 30

1) Problems in early growth and development 2) Stillbirth and neonatal death 3) Infertility 4) Family History 5) Neoplasia 6) Pregnancy for mother of advanced maternal age

Answer 31

``` Blood (somatic cells) Cheek Cells (somatic cells) ``` Amniocentesis or CVS (prenatal screening)

Answer 32

Grow cells and stain DNA | Few days in between taking sample and getting diagnostic

Answer 33

Polyploid cells and organisms are those containing more than two paired (homologous) sets of chromosomes

Answer 34

presence of an abnormal number of chromosomes in a cell, for example when having 45 or 47 chromosomes when 46 is expected in a human cell.

Answer 35

the number of sets of chromosomes in a cell, or in the cells of an organism.

Answer 36

Euploidy is the state of a cell or organism having the same number of each homologous chromosome

Answer 37

trisomy and monosomy

Answer 38

associated more with oocytes than spermatocytes | can be traces back to meiosis

Answer 39

rate of nondisjunction pretty steady up until 34-35 with rise increase after that

Answer 40

practice guideline on prenatal aneuploidy screening and maternal age maternal age independent- b/c improved low risk/noninvasive screening methods

Answer 41

Recommended for trisomy 13, 18, 21 can be offered for sex chromosome aneuploidy and possibly clinically relevant deletions ``` complications: maternal weight maternal aneuploidy organ transplant gestational stage ```

Answer 42

13, 18, 21, X, Y

Answer 43

Meiosis 1 in mother

Answer 44

post-zygotic mitosis

Answer 45

triploid- 3N trisomy- 2N + 1

Answer 46

Results in number of normal cells and few trisomic and monosomic cells The monosomic cells have a hard time surviving so die out The trisomic (aneuploid) cells only 25% of total cell volume and thus less severe Phenotype also depends on which cells have the trisomy

Answer 47