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FMS > Introduction to Genetics and Clinical Genetics > Flashcards

Introduction to Genetics and Clinical Genetics Flashcards

1
Q

Summarize the process of translation with all important enzymes.

A

1) RNA Pol binds to DNA.
2) Pol melts duplex DNA near transcription start.
3) Pol catalyzes phosphodiester link on 2 initial nucleotides and then advances down template strand 3’ to 5’ while synthesizing RNA 5’ to 3’
4) At transcription stop site polymerase releases DNA and RNA.

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2
Q

TFIID

A

Binds TATA box. Forms Pre-initiation complex.

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3
Q

TBP

A

TATA binding protein. Portion of TFIID that actually binds the TATA Box

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4
Q

TFIIB

A

Binds to PIC complex after TFIID

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5
Q

Core Promoter recognition sites and proteins.

A

TBP= TATA
TAF1 & TAF2= Inr
TAF6 & TAF9= DPE

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6
Q

Regulatory Promoter Sites

A 
Regulatory= promoter
Sites= GC, CCAAT
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7
Q

How does the mediator complex play a role in activation and repression?

A 
Activation= Coactivators and UAS activate mediator which activates TFIID and CFD
Repression= repressors inactivate mediator, UAS and activators. Mediator then inactivates TFIID and TBP
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8
Q

CTD

A

Carboxy Terminal Domain of RNA Pol. Plays 2 roles. Phosphorylation allows binding of RNA Pol to Core Promoter. Phosphorylation also allows the 7-MeG cap to use as a dock before capping RNA

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9
Q

Polyadenylation

A

The process of adding a PolyA tail via Pol(A) polymerase

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10
Q

PABPN1

A

Coats PolyA Tail. Stops synthesis at A x 200-300. trinucleotide repeat on this gene= oculopharyngeal muscular distrophy

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11
Q

5’ splice site is

A

G-GU

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12
Q

3’ splice site is

A

AG-G

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13
Q

mRNA splicing mechanism

A

two nucleophilic substitution reactions. catalyzed by the spliceosome= 300 proteins and several snRNPs

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14
Q

Lupus

A

Autoimmune disease. inflammatory symptoms due to autoimmune activity against snRNPs

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15
Q

zip code binding protein

A

attaches mRNPs to mRNA and motor proteins to move RNA to different regions of the cell for synthesis

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16
Q

modified scanning hypothesis

A

40s attaches. scans down 5’ to 3’ looking for AUG in proper context. ACCAUGG. when found 60s is recruited and complex begins translation

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17
Q

PABPI

A

Protein on Poly A tail which Regulates translation on 5’ end

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18
Q

tRNA role in translation

A

stacking. aminoacyl joins peptidyl +AA is stacked then converted to peptidyl

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19
Q

How do many antibiotics work?

A

inhibiting translation

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20
Q

Nonsense Mediated Decay

A

activates in RNA with premature stop codons. UTF2 binds UTF3 to form functional EJC. Complex bridges to ribosome and activates decay

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21
Q

Nonstop Decay

A

detects mRNA with no stop codon. Ribosome stalls on PolyA tail. PABPC1 flies off. either ski7 + degrades from 5 end or decapped and degrades 3-5

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22
Q

No Go Decay

A

degrades mRNA with no start codon. Dom34-Hbs1 binds to stalled ribosome and activates endonucleolytic cleavage and decay.

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23
Q

OPMD

A

Dysphagia, Dysphonia, Facial weakness, proximal limb weakness, 100% penetrant, autosomal dominant, trinucleotide repeat

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24
Q

Chromosome disorders

A

abnormalities in number or structure of chromosomes. not very common

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25
Q

single gene disorders

A

alterations in coding sequence produce effects on function of protein. Usually mendelian based

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26
Q

Mitochondrial disorders

A

separate genome. can be disrupted in the same way as nuclear DNA but only maternally inherited. passed in cytoplasm of ovum.

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27
Q

Multifactorial disorders

A

combination of genes + environment

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28
Q

Polygenic

A

many genes play a role

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29
Q

teratogenic

A

environment primarily

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30
Q

Mosaicism

A

more than one genotype

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31
Q

Imprinting

A

parent of origin different in expression

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32
Q

uniparental disomy

A

both chromosomes from 1 parent

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33
Q

unstable triplet repeats

A

develop by expansion of normally present trinucleoside repeats

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34
Q

Inheritance Patterns tools work for which kind of disorders

A

single gene disorders.

e.g. pedigrees ect,

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35
Q

karyotype

A

detects alterations in chromosome # and very large mutations

36
Q

FISH

A

synthesized DNA is labelled and denatured then paired to control and patient chromosomes.

37
Q

Comparitive Genomic Hybridization

A

patient DNA and control DNA dyed and put in wells. cannot detect small deletions or duplication

38
Q

What do we use for small mutations?

A

sequencing. individual gene, exome, or whole genome.

39
Q

What are replication errors and how do we fix them?

A

base mismatches and base insertion. we fix it with mismatch repair which repairs individual base pairs.

40
Q

Explain damage from cell environment and how it is repaired.

A

acid and heat of metabolism. also O2 radicals. removes purines.
Uses BER

41
Q

How does UV light damage cells and how does the cell fix it?

A

sunlight= creates DNA base adducts (cyclobutane dimers, 6-4 photoproduct). Direct repair via photolyase. NER.

42
Q

Explain Ionizing Radiation and how do we fix it

A

xrays= single/ double strand bond breaks. Double strand breaks are repaired through homologous repair and end rejoining

43
Q

Chemical exposure how does it happen and how do we repair it.

A

smoking, fossil fuel, foods. They create polycyclic aromatic hydrocarbons (PAH). heterocyclic amines.

44
Q

What is interstrand crosslink repair?

A

It is a mechanism for repairing damage to one DNA strand. In G1 this takes the form of unhooking, translesion synth and then NER.
In S phase there is no need to unhook so it goes straight to NER or homology driven repair.

45
Q

xeroderma pigmentosum

A

defect in NER. 1000x increased risk of skin cancer. mutation in one of 8 XP genes used in NER complex.

46
Q

Ataxia telangiectasia

A

mutations in ATM gene which is required for homologous recombination. ataxia in infancy. telegiectasia in childhood. bulbar conjunctivae
immunodeficiency.
may progress to malignant

47
Q

Werner syndrome

A

premature aging, mutation in WRN gene which unwinds DNA for HR and replication. They get old person diseases.

48
Q

Bloom syndrome

A

mutation in BLM gene which codes for helicases like WRN. Also important in decatenation.
Skin sensitivity, narrow face, short, immunodeficiency, retardation, cancer risk.

49
Q

BRCA1/ BRCA2 dependent inherited breast cancer

A

involved in homologous recombination repair, also ovarian and fallopian tumors.

50
Q

Dominant Disorders

A

Marfans, Achondroplasia, NF1

51
Q

Recessive Disorders

A

CF, PKU, most inherited metabolic diseases

52
Q

What are some confounders to identifying causes in genetic disorders.

A

expressivity
consanguinity
de novo mutations
mosaicism

53
Q

germline mosaicism

A

presence of more than one genetically distinct cell line

54
Q

penetrance

A

% of people who carry a pathogenic variant who express the trait

55
Q

Variable expressivity

A

traits vary between individuals who carry the gene mutation

56
Q

Retinoblastoma mutation

A

Autosomal Dominant. 10% have no symptoms. retinal tumor. reduced penetrance. 2 hit hypothesis (Knudsens)

57
Q

NF1

A

neurofibromatosis 1. cafe au lait macules. axillary/inguinal freckling. neurofibromas. lisch nodules (iris). bony lesions and tibial bowing. penetrance 100%, expressively variable, de novo in 50%

58
Q

Marfans

A

Michael Phelps disease. FBN1 gene (fibrillin). Major criteria: dialated aortic root and ectopia lentis. Other: skeletal changes, dural ectasia. 25% de novo. some mosaicism.

59
Q

Achondroplasia

A

most common form of short limbed dwarfism. complete penetrance. fibroblast growth factor receptor gene (negative regulator)= activation mutation= lower bone growth. fathers germline.

60
Q

traits of autosomal recessive diseases

A

complete penetrance, heterozygous= 50% function, usually enough
early onset of symptoms

61
Q

Sickle cell

A

Point mutation on HbS. HbS heterozygosity does seem to protect against malaria

62
Q

CF

A

most common AR in Caucasians. sweat chloride test. infants= meconium ileus
infancy= fail 2 thrive, pneumonia
adults= azospermia, bronchiectasis.

63
Q

PKU

A

inability to to process PHE. microcephaly, severe MR, epilepsy, variable expressivity, can pass maternally through placenta.

64
Q

topoisomerase

A

slides down DNA unwinding superhelical turns

65
Q

irinotecan

A

topoisomerase inhibitors are used in cancer chemotherapy

66
Q

Pol A/primase

A

initiates DNA replication

67
Q

DNA Polymerase gamma/ episilon

A

elongation

68
Q

How does DNA Pol stay on DNA

A

beta clamp.
clamp= PCNA
brace= RFC

69
Q

How does P53 affect DNA Pol

A

P53 to P21 to PCNA inactivation. inactivates DNA Pol

70
Q

What controls the start of DNA replication

A

Origin of Replication Complex (ORC) binds to MCM helicase. inactivation happens when ORC binds to Cdc6

71
Q

telomerase

A

enzyme that has RNA component. fills in 3’ overhangs on okazaki fragments. telomerase higher in dividing cells

72
Q

How does DNA repair replication errors?

A 
proofreading= 1/10^7
mismatch= 1/10^10
73
Q

Lynch Syndrome

A

Heriditary Non-polyposis Colon cancer. inherited mutations in mismathc repair. MSH2 or 6. May be found by examining microsatellite instability. few polyps. very rare after 40 yrs.

74
Q

What is Trans Lesion Synthesis

A

DNA damage that can be tolerated and bypassed during replication. replisome switches DNA Pol to one that “guesses” what base to insert. Cancer cells love it.

75
Q

spontaneous abortions are caused by

A

60% defects, 40% normal. our of the 60 nearly half are trisomy.

76
Q

Trisomy 21

A

Downs. 1/800 Live births. mainly nonfamilial. simian creases (not called that but i cant remember otherwise), upslant palpebral fissures, heart disease, otitis media, hypothyroidism. mostly nondisjunction. can also occur from robertsonian translocation

77
Q

How does maternal age affect risk of abnormality

A 
1/1215= Age 15
1/5= Age 50
78
Q

Trisomy 18

A

Edwards. short sternum. digit abnormalities. round head. posterior rotation of ears. low hairline. high nasal bridge. semi-lethal= 10% survival rate past year 1.

79
Q

Trisomy 13

A

Patau. Holoprosencephaly. heart defects (VSD). cleft lip/ palate. microcephaly. rocker bottom feet.

80
Q

5p

A

Cri-du-chat. Cat like cry due to hypotonia and laryngeal abnormalities. growth restriction. microcephaly. moderate to sever intellectual deficit .

81
Q

22q11.1 deletion

A

May manifest as Digeorge or Velocardialfacial. facial dysmorphology, slow growth, cleft palate. may have heart problems like tetralogy of fallot or aortic arch interrupt

82
Q

Turner syndrome

A

in females. loss of second x. short stature. may have edema or webbing (webneck).

83
Q

Klinefelter

A

XXY. can also include multiple x variants although this leads to mental deficits. normally found after Azospermia.

84
Q

xxx,xyy

A

not syndromes typically. can have normal chromosomes

85
Q

Williams (contiguous gene deletion syndrome)

A

puffy eyes, blue eyes, cocktail personality, aortic stenosis, hypercalcemia

86
Q

WAGR

A

aniridia, wilms tumor, late onset kidney dysfunction, undescended testes

87
Q

46, XY, female

46,XX, male

A

-SRY mutations where the SRY gene usually found on the Y gene may abnormally crossover and create variants.

FMS (3 decks)

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