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Foundations 1 > 8/8/17 > Flashcards

8/8/17 Flashcards

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1
Q

Osteogenesis Imperfecta

A

Type I: fractures of arm and leg bones, heal normally, have half of normal procollagen amount so Loss of Function mutation, blue sclera

Type II: bunch of bone fractures at birth, die soon, mutant collagen

Dominant negative LOF mutation

Substitute Gly in collagen

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2
Q

Achondroplasia

A

Autosomal dominant, fibroblast growth factor 3 (FGFR3)

Mutation so stabilize FGFR3 dimers, constitutively activate a negative regulator, increase with dad age

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3
Q

Anticipation

A

Occurrence of genetic disease at an earlier age of onset and with increasing severity in successive generations

Triplet repeats tend to expand, intron is FA

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4
Q

Huntington’s Disease

A

Autosomal dominant, high penetrance

Personality changes, motor probs, memory loss

Caused by polyglutamine mutation

Initial: impaired muscles, forgetful, personality change

Middle: involuntary and voluntary uncontrolled, slur speech, depress and crazy

End: immobile, mind is nonfunctional

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5
Q

Duchenne Muscular Dystrophy

A

1/3 are point mutations and insertions

Haldane Hypothesis

X-linked disorder

Myofibe degeneration and regeneration with adipose and connective tissue, calf pseudohypertrophy

Cardiomyopathy, retarded, die early

Dystrophin protects striated muscle membranes from damage by linking actin to ECM, is absent in DMD

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6
Q

Haldane Hypothesis

A

1/3 of mutant alleles are lost each gen in X-linked, if disease frequency is constant then 1/3 must be new mutations

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7
Q

Becker muscular dystrophy

A

Mutations in dystrophin gene but milder and onset

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8
Q

Spinal muscular atrophy

A

Autosomal recessive, LOF of SMN1

Muscle atrophy, SMN1 has a deletion that prevents it from making 90% of SMN transcript so SMN2 (with a single base change from SMN1) makes a small amount

Severity depends on SMN2 copy number

Type 1: Werdnig-Hoffman disease, floppy muscles and breathing probs, die before 2

Type 2: sit but not stand, die as a kid

Type 3/4: milder, adult survival

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9
Q

SMA treatments

A

Spinraza: exon skipping to include exon 7, intrathecal

Avexis: gene therapy, intravenous

Better motor milestones than SMA Type 1

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10
Q

Allelic heterogeneity

Locus heterogeneity

Clinical heterogeneity

A

Multiple Diff mutations in same allele

Mutations in more than one gene

Diseases have diff phenotype but caused by same phenotype

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11
Q

Mitochondrial diseases

A

Affect high aerobic tissues like eyes, nervous system, cardiac, and muscles

Leber hereditary optic neuropathy, MERRF, and MELAS

Affected males don’t transmit to kids

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12
Q

Satellite DNA

A

Alpha-satellite: kinetochores of all chromosomes

Beta-satellites: variable regions of 1,9,Y, and acrocentrics

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13
Q

SNP

A

A change in DNA that occurs in at least 1% of the population

Responsible for most variation in gene expression

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14
Q

UV Radiation Effect

A

Thymine dimers that need nucleotide excision repair

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15
Q

Alkylation and cross linking agents

A

Cytoxan and tobacco

Add methyl to G and may cross link DNA strands

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16
Q

Demaminatin of C

A

Converts to U so one strand binds with A instead of G

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17
Q

ROS

A

Makes 8-oxoguanine

Now pairs with A or C

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18
Q

Fragile X Syndrome

A

Retarded, big ears and jaw, big balls

Triplet repeat mutation, RNA binding protein (FMRP) for translation regulation and synaptic plasticity plasticity

5’CGG repeat gets enlarged during maternal meiosis which causes miRNAs to methylated the 5’CpG island, only occurs after a certain CGG repeat size threshold

Example of anticipation

GOF: trigger miRNA release
LOF: transcription shuts down for the neuroplastic gene

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19
Q

Red-green color blindness

A

Red and green located on X chromosome

Unequal crossing over

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20
Q

Hemoglobin Lenore

A

Fusion of beta globin genes due to unequal crossing over

Delta beta fusion

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21
Q

Dominant Negative Mutation (LOF)

A

Heterozygous alleles

Mutant polypeptide loses own function AND interferes with function of the normal allele

More than 50% reduction in function

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22
Q

RET GOF mutation

A

Transmembrane receptor with tyrosine kinase domains that activate MAPK pathway for transcription

Can cause Multiple Endocrine Neolasia 2, a thyroid cancer

Missense mutations that that cause excess reaction to ligand, constitutively active receptors, overproduction of neuroendocrine cells

Changes to Cys a big thing

GOF mutation

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23
Q

Friedrich Ataxia

A

GAA repeats in intron

GOF: heterochromatin formation
LOF: transcription shit down

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24
Q

Myotonic dystrophy

A

CTG in 3’ UTR

GOF: attract RNA binding proteins from extra RNA, abnormal splicing of other gene transcripts like insulin receptor and muscle chloride channel

LOF: other transcripts

Open, triangular shaped mouth in baby
Weird face

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25
Base excision repair
Fix most common DNA damage, purine loss and 8-oxoguanine MUTYH involved in 8-oxoguanine repair LOF muatins lead to colorectal cancer
26
Xeroderma pigmentosum
Nucleotide excision repair prob Skin and eyes sensitive to UV, get skin cancer Autosomal recessive
27
Complementation
Single allele mutations in two diff loci don't produce disease
28
Mismatch repair
Replication errors like mismatch nucleotides, microsatellites MLH1/PMS2 and MSH2/MSH6 recognize mismatch and recruit other repair machinery like EXO1
29
Lynch Syndrome Hereditary nonpolyposis colorectal cancer
Defective base mismatch repair leads to cancers like colorectal and ovarian Mutations in 4 mismatch repair genes plus EPCAM, which prevents transcription of MSH2
30
DsDNA damage signal and repair syndromes
Maintenance of structure and integrity of DNA (helicase): Bloom syndrome Signal the repair process: ataxia telangiectasia Locate damage and trigger repair: Fanconi anemia Repair of DNA: BRCA 1 and 2 End-joining of dsDNA: Nijmegen breakage syndrome
31
Bloom syndrome
Maintenance: suppression of recombination DNA RecQ helicase Predisposed to most cancers, excess sister chromatid exchanges that can lead to unbalanced exchanges Short stature
32
Ataxia telangiectasia
Signals BRCA of chromatin changes like by ionizing radiation Difficulty with movements and chromosomal instability, cancer
33
Franconia anemia
LOF recessive Sensitive to DNA damage like cross links Short stature,skin hyperpigmentation, malformed kidneY and limb, bone marrow failure Locate and trigger
34
Nijmegen breakage syndrome
Super rare Short, progressive small head, immunodeficiency, and increased non-Hodgkin lymphoma End joining of dsDNA
35
HereditRy breast/ovarian cancer syndrome
Single LOF mutation, autosomal dominant phenotype (only non biallelic LOF recessive) Higher breast and ovarian cancer plus prostrate in dudes
36
SsDNA break repair
PARP1: poly[ADP-ribose]polymerase 1 PARP1 inhibitor for chemo for BRCA mutation: eliminating one DNA repair pathway leads to genome instability like cancer, eliminating both repair pathways leads to cell death
37
Nuclear transport
Prospective protein has a positive nuclear localization signal that binds to nuclear import receptor, nuclear import receptor moves down cytosolic fibrils and releases protein
38
Mitochondrial transport
Precursor protein with positive N terminal signal sequence binds to the import receptor protein, protein unfolded to be threaded through intermembrsne space and past protein translocator in inn
39
Ribosome location
Proteins destined to be translated on ER-bound ribosomes have ER import sequence, located on N terminus Signal recognition particle binds to ER signal sequence and then binds to SRP receptor on ER Stay in cytosol if have no ER import signal sequence
40
ER embedded proteins
Protein threaded through protein translocator until hit hydrophobic stop transfer sequence, spit out, signal peptidase cleaves N terminal signal sequence
41
Swyer Syndrome XY gonadal dysgenesis
Mutation in SRY Normal guy karyotype but external female genitalia without ovaries SRY is a TR that initiates sex determination in embryogenesis Can be from mutations in nuclear localization signal of SRY
42
Alpha thalassemia
Deletions of 1-4 alpha globin genes 3 deleted copies gets kinda serious, Hemoglobin H disease 4 deleted is Hemoglobin Bart's with 4 gamma subunits, neonatal death
43
Beta Thalassemia
Many different types of mutations cause this Thalassemia major is Cooley's anemia, with enlarged organs and bones deformed
44
Heinz body hemolytic anemias
Point mutation in Beta subunit Denature Hb molecule Coagulation in the erythrocyte
45
Better to have increased or decreased oxygen affinity?
Decreased since increased is more severe
46
Sickle Cell anemia
Single point mutation (Hb S) changes Glu to Val (BGlu6 to Val) Hydrophobic patch makes sticky in T state and polymerize
47
Hemoglobin C
Glu6Lys West Africa Milder anemia due to reduction in RBC lifespan
48
Not bad Hb variants
Hb E and Hb I Involve point mutations that have AA with opposite charge Both variants arose independently
49
Hb glycosylation
Not enzymatic, proportional to glucose conc. Used for HbA1c levels Little effect on function
50
Levinthal's Paradox
10 possible conformations for each AA Proteins can't fold randomly because it would take ridiculously long, so a predetermined path must exist
51
Foldon
Units that fold in a single cooperative step Secondary structure elements
52
Anfinsen Conclusions
Info for folding is in primary structure Folding is thermodynamically controlled, no need for energy
53
Consequences of Excluded Volume Effect
Increase: effective conc., asosociation rate constants of large molecules, Rate of aggregation Decrease apparent solubility
54
Proteins at risk for aggregating
Names can't chains synthesized from polysomes: growing chains close together not fold but aggregate Nuclear proteins: crowded and charged macromolecules Mutant proteins: Unfolded proteins under environmental stress like heat
55
Foldases
Catalyze rate-limiting step in folding
56
Peptidyl-prolyl CIA trans isomerase PPI
Accelerates folding cuz catalyze CIA and trans isomer conversions of Pro peptide bonds
57
Protein disulfide isomerase
Catalyze disulfide interchange reactions, which is rate limiting in ER lumen Localized to ER
58
Anfinsen Cage
Sequester polypeptide to prevent aggregation and provides appropriate folding environment Found in chaperonin
59
Systemic amyloidosis
Extra cellular deposition and accumulation of insoluble protein Amyloid have beta sheet structures that cross link Transthyretin binds and transports thyroid hormone and vitamin A through the body
60
Alpha-1-antitrypsin deficiency AATD
Alpha-1-antitrypsin is stuck in liver and can't go to lungs, helps protect lungs from neutrophil elastase Caused by incomplete folding or aggregation
61
Alzheimer's disease
Beta amyloid plaques Example of localized amyloidosis Secretase cuts APP (a large precursor protein) to form beta amyloid Abnormal postranslational modifications of precursor proteins
62
Molecular chaperones
Decrease rate of aggregation Can work in tandem Some require ATP Prevent inappropriate interactions among proteins
63
Prions
Infectious agents composed of misfiled proteins Spongiform encephalopathy

Foundations 1 (19 decks)

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