lecture 4

Question 1

in FISH what size must the probe be?

Answer 1

smaller than the deletion

Question 2

why must the probe be smaller than the deletion

Answer 2

to discriminate between wild type and mutant allele

Question 3

what happens if the probe is bigger than the deletion?

Answer 3

it will hybridize with the mutant allele and not be able to discriminate between them

Question 4

what is special about metaphase FISH?

Answer 4

can see all the chromosomes

Question 5

mutation that cause DiGeorge Syndrome?

Answer 5

22q11 deletion

Question 6

symptoms of which disease?
CATCH 22
cardiac defects
abnormial facies 
thymic hypoplasia 
cleft palate 
hypocalcemiaf from parathyroid aplasia 
chromosome 22 deletion

Answer 6

DiGeorge Syndrome

Question 7

whats the advantage of MLPA over FISH

Answer 7

**review

Question 8

what is array comparative genome hybridization (array-CGH)?

Answer 8

compare cells from normal cells (control) to cells from a patient
label both samples with diferent fluorochromes and hybridize to a plate

Question 9

how is the result displayed in CGH?

Answer 9

plot ratio of green to red, each black spot represent a locus.

Question 10

what is the problem with CGH?

Answer 10

only detect numerical not unbalanced abnormalities.

cant detect inversions for example

Question 11

in a CGH graph what does it mean when the spots go down or up?

Answer 11

down: deletion
up: addition

Question 12

general rule for an autosomal dominant disease?

Answer 12

will die out in the family, the individuals are selected against usually

Question 13

sanger (dideoxy) DNA sequency?

Answer 13

based on DNA synthesis, durint the synthesis trigger random termiation at specific bases.
these random termiations are caused by dideoxy NT.

Question 14

what happens when dideoxy is incorporated into the synthesis? why?

Answer 14

stops transcription. because it doesnt have a 3’ OH

Question 15

Dye-terminator sequence?

Answer 15

label the dideoxy nucleotide, so instead of having to use gel electrophoresis to separate the fragments

Question 16

advantage of dye-terminator sequencing?

Answer 16

can use higher voltage to separate the fragments,
its faster
it doent use radioactive labels

Question 17

how are fragments separated in dye sequencing ?

Answer 17

separated by size using capillary electrophoresis

Question 18

how are results interpreted in dye terminator sequencing?

Answer 18

the detector plots the fluorescent signal in a sequence chromatogram

Question 19

R200Q mutation

Answer 19

Arginine at position 200 is replaced by glutamine

Question 20

R200Q mutation

Answer 20

Arginine at position 200 is replaced by Q

Question 21

notation to express introns and exons?

Answer 21

Intron: lower case
exon: upper case

Question 22

what type of mutation causes Beta-thalassaemia?

Answer 22

NULL mutations in the Beta-globin gene

Question 23

what cant the next generation sequencing be used for?

Answer 23

organism without a reference genome. (de novo sequence) like a new species of bacteria that is causing a disease

Question 24

what are the advantages of using next generation sequencing?

Answer 24

• orders of magnitude faster and less expensive

- useful for whole genome re-sequencing

Question 25

disadvantages of next generation sequencing?

Answer 25

• not targeted, cant sequence a single gene
• short read lengths not useful for de novo sequencing
• higher error rate, sequencing depth is necessary