Dynamic mutations #12

Question 1

repetitive DNA accounts for what percentage of the genome?

Answer 1

51%

Question 2

how much of our genome consists of satellite sequences?

Answer 2

3%

Question 3

what are the 3 categories of satellite DNA? What are they divided by?

Answer 3

~satellite
~mini-satellite
~micro-satellite
By the dimension of their tandem repeats

Question 4

Where are satellites found? How many tandem repeats are in an alpha satellite?

Answer 4

171 bp repeats, they are found near DNA centromeric position

Question 5

Where are mini-satellites found?

Answer 5

near DNA with tandem repeats of 6-64 bp, they are highly polymorphic in the pop., the typical # of repeats are 7-80

Question 6

where are micro-satellites found

Answer 6

in DNA with tandem repeats of 2-5 bp, they are highly polymorphic in the pop., the typical #of repeats is 5-40

Question 7

microsatellites are also known as

Answer 7

short tandem repeats, there is a microsatellite every 1000nt

Question 8

with each passing of a generation the size of the microsatellite will

Answer 8

increase, as the mutation rate is higher here than other parts of our genome

Question 9

unequal crossing over

Answer 9

due to the formation of a hairpin in the microsatellite region of one chromosome, and subsequent crossing over of this region, we are left wit unequal crossing over

Question 10

the polymerase slippage phenomenon

Answer 10

can cause an increase or decrease in length of the repeat

Question 11

note

Answer 11

unlike mendelian disorders mutations are not stably transmitted between generations

Question 12

This is called genetic anticipation

Answer 12

is a type of inheritance characterized by:
~ a decreasing age of onset
~ an increasing severity of individuals
~ could also have increasing penetrance

Question 13

what diseases can be characterized by genetic anticipation

Answer 13

~myotonic dystrophy
~huntingtons disease
~spinal and bulbar muscular atrophy
~ kinds of ataxias
~fragile X syndrome

Question 14

mutations in anticipation diseases were due to?

Answer 14

continuous expansion of CnG (CAG)

Question 15

who is more stable short/long alleles?

medium alleles are called?

Answer 15

~short alleles

~ pre mutated

Question 16

trinucleotide expansion disorders have 3 classes

Answer 16

~CLASS A: expansion affecting intergenic, untranslated/intronic regions
~CLASS B: expansion affecting exons and leading to a poly-glutamine trait
~CLASS C: expansion affecting exons and leading to a poly-alanine trait

Question 17

fragile X syndrome has

Answer 17

an expansion in the 5’ untranslated region

Question 18

huntingtons disease has a

Answer 18

expansion in the coding sequences

Question 19

myotonic dystrophy I has

Answer 19

an expansion in the 3’ UTR, on DMPK gene ch19

Question 20

fragile X syndrome

Answer 20

FMR1 on chXq27.3 (is an RNA binding protein - can repress translation, increase stability of RNA, help RNA transportation out of nucleus)
mild to moderate mental retardation
martin bell syndrome
more in males

Question 21

autosomal dominant disease

Answer 21

~HTT gene on ch4p

~polymorphic repeat in exon 1

Question 22

Huntingtons disease

Answer 22

is an inherited progressive neurodegenerative disease

Question 23

MBNL 1

Answer 23

regulates alternative splicing