Genetics II Flashcards Preview

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Flashcards in Genetics II Deck (61)
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1
Q

Regarding the tri nucleotide repeat associated with Huntington’s disease, it is a…

A

CAG repeat that occurs in the Exon

2
Q

CAG repeat occurring in the Exon

A

Huntington’s disease

3
Q

What complex in the ETC (respiratory chain of the mitochondria) does NOT contain Mitochondrial DNA?

A

Complex 2

4
Q

If a couple both expresses Achondroplasia, what is the chance their offspring will have the lethal form of the gene?

A

25%

*Both are Heterozygous

5
Q

Amelogenesia imperfecta with mutation p.Trp153.

What does this indicate?

A

Stop Codon was Created

6
Q

c200+IG>A

What kind of mutation is this?

A

Splicing mutation

7
Q

If a woman is a carrier for sickle cell and her husband is not, what has happened if her son expresses the trait?

A

Maternal MII error

*MII will essentially double the error

8
Q

The repeating CCG expansion of the 5’ UTR found in Fragile X Syndrome have over _____ repeats in affected individuals.

When over this number, _______ causes promoter modification and the cessation of RNA production

A

200

Methylation

9
Q

Autosomal Dominant disorders rarely have what mechanism of disease?

What are 3 mechanisms seen in Autosomal dominant diseases?

A

Loss of Function

Dominant negative, Gain of Function, Haploinsufficiency

10
Q

Type 1 Osteogenesis imperfecta W/O Dentinogenesis is due to what molecular mechanism?

A

Haploinsufficiency

11
Q

Type 1 Osteogenesis imperfecta WITH Dentinogenesis is due to what molecular mechanism?

A

Dominant Negative

12
Q

Cystic Fibrosis has different mutations in the same gene giving the same clinical phenotype - what is this called?

A

Allelic heterogenicity

13
Q

Different mutations in different genes resulting in the same clinical phenotype is called…

A

Locus heterogenicity

14
Q

CGG repeat in the non-coding 5’UTR:

A

Fragile X

15
Q

CAG repeat in the 1st exon:

A

Huntington Disease

16
Q

GAA repeat in the intron:

A

Freidreich Ataxia

17
Q

CTG repeat in the non-coding 3’UTR:

A

Myotonic Dystrophy

18
Q

Fragile X:

A

CGG repeat in the non-coding 5’UTR

19
Q

Huntington Disease:

A

CAG repeat in the 1st Exon

20
Q

Freidreich Ataxia:

A

GAA repeat in the Intron

21
Q

Myotonic Dystrophy:

A

CTG repeat in the non-coding 3’UTR

22
Q

What is the inheritance pattern for Achondroplasia?

A

Autosomal Dominant

*Fibroblast Growth Factor Receptror 3

23
Q

_____% of individuals affected with Achondroplasia are de novo mutations on the _______ chromosome

A

80

paternal

24
Q

The majority of individuals affected with Achondroplasia have a ______ to ______ substitution at codon 380.

A

Glycine

Arginine

25
Q

99% of Achondroplasia is a ___ to ____ transition (purine for purine

1% of Achondroplasia is a ___ to ____ transversion (purine to pyrimidine)

A

G to A

G to C

26
Q

T/F
Mutations causing Achondroplasia can cause an alteration of restriction sites leading to shorter DNA fragments

T/F
Mutations causing Achondroplasia can lead to “gain of function” - new or enhanced function of the gene

A

True

True

27
Q

How is Achondroplasia diagnosed?

A

PCR

28
Q

Huntington’s disease is what type?

A

Autosomal Dominant

29
Q

The age of onset changing in a disease indicates what?

A

Anticipation

30
Q

Differential inheritance from mother or father indicates what?

A

Imprinting

31
Q

T/F

Huntington’s exhibits both Anticipation and Imprinting:

A

True

32
Q

If No band is visible in Fragile X testing, the male is either ______ or ______.

A

Premutation

Full mutation carrier

33
Q

If someone has inherited a mutant allele but isn’t expressing the phenotype, this may be an example of…

A

Penetrance (or non-penetrance)

***light switch

34
Q

If someone has inherited a mutant allele and may express the trait to variable degrees (different severity), this is an example of…

A

Variable Expressivity

35
Q

The increased severity and/or decreased age of onset of disease with successive generations is…

A

Anticipation

36
Q

What reflects an increased number of repeats passed from generation to generation?

A

Anticipation

37
Q

What is the differential modification and expression of alleles of genes depending on the Sex of the parent of origin?

(it matters who gives you what)

A

Imprinting

38
Q

Prader-Willi and Angleman are best examples of what?

A

Imprinting

39
Q

How many human genes have been discovered that show Imprinting expression?

A

31

40
Q

Inheritance of 2 copies of a gene/chromosome from one parent is called what?

This has implications for what kind of disorders?

A

Uniparental Disomy

Recessive and Imprinted disorders

41
Q

Fragile X testing, 60-200 copies is…

A

Premutation

42
Q

Fragile X testing, over 230 copies is…

A

Full mutation carrier

43
Q

A PCR test for Fragile X will only detect up to 100 copies, if someone has the mutation, what test will confirm?

A

Southern Blot

44
Q

What type of genetics has a high mutation rate, limited proofreading/repair, and lack of protective histones?

A

Mitochondrial

45
Q

Define MItochondrial Heteroplasmy:

A

Both wildtype and mutant mito DNA

46
Q

What is the Threshold Effect of Mitochondrial DNA?

A

Certain min. number of mutant proteins must be present before Expression occurs

47
Q

T/F

Mitotic Segregation occurs in Mitochondrial genetics

A

True

48
Q

p.Gly17Arg

A

AA substitution

Missense

***point mutation

49
Q

p.Gly17*

A

Stop Codon

Nonsense

  • = stop
50
Q

p.Leu6Hisfs*3

A

Frameshift mutation

either deletion or duplication has occurred, now there’s a Stop codon

51
Q

De Novo mutation on Mom’s allele:

A

NOT Achondroplasia

52
Q

Achondroplasia detected by:

A

PCR restriction detection

53
Q

Achondroplasia AA consequence:

A

AA lethal

54
Q

c.101-2A>T

A

Splicing

55
Q

T/F

Penetrance is binary

A

True

Either are or aren’t penetrant

56
Q

T/F

Variable expressivity is a function of penetrance

A

True

57
Q

What needs to occur for Uniparental Disomy to take effect?

A

Must kick out other paren’t chromosome

*otherwise trisomy

58
Q

Mitochondrial Heteroplasmy =

A

wildtype and mutant DNA

59
Q

T/F
Mitochondrial DNA has bigger mutation rate because no histones, no proofreading, and is at a site of radical oxidative formation

A

True

60
Q

Beginning with a single DNA strand, how many cycles of PCR = 1 million copies

A

20

61
Q

If a woman has 2 populations of mitochondrial DNA, one of which contains a mutation, this is an example of…

A

Heteroplasmy

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