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Unit 3: LGS > Week 2 > Flashcards

Week 2 Flashcards

1
Q

Genotype

A

genetic make-up of an organism

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2
Q

Phenotype

A

physical presentation

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3
Q

Do all cells have the same genotype

A

Yes but they express diff. genes so they make diff set of functional proteins which make the cell function

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4
Q

Locus

A

location of specific genes on chromosomes

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5
Q

Alleles

A

two copies of the same gene located on two homologous chromosomes

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6
Q

Mutation

A

-sudden changes in the seq. of the DNA which can occur due to environmental influences or internal processes - change in the DNA sequence then that’ll affect mRNA which will affect proteins which could lead to lack of function of the protein

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7
Q

Mutation in exon

A

leads to abnormal protein which leads to a diseased state

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8
Q

Spliceosome

A

small nuclear RNA and small nuclear proteins that make up a complex that take out non-coding sequence and keep in coding sequence to make mature mRNA

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9
Q

Mutation to spliceosome

A

change in sequence of mature mRNA; introns might be left in the sequence which could lead to instability of mRNA

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10
Q

Mutation in poly A tail or 5’ cap

A

lead to instability of mRNA which won’t affect protein struct. But will result in less protein being produced

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11
Q

Mutation of regulatory sequences

A

-silencors, promotors; -affect transcritpion rate; -would lead to either inc. or dec. amounts of protein but wouldn’t change protein struct.

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12
Q

Loss of protein function

A

-protein will lose some part of functioning -ex: tumor suppressor gene: no longer able to stop cell cycle

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13
Q

Gain of protein function

A

-protein will gain function -ex: pro-oncogene: will cause it to become oncogene and increase cell cycle replication -ex: achondroplasia; Hb Kempsey - can’t release oxygen anymore

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14
Q

Novel property function

A

-provides the protein with novel property -ex: sickle cell: shape of protein is changed by mutation due to misfolding -change in dosage of gene; increased chromosome number; klinefelters, turners

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15
Q

Achondroplasia and endochondral ossification -type of mutation

A

-Gain of function in FGFR3 (fibroblast growth factor receptor 3) -This is a tyrosine kinase receptor that binds several growth factors that has a casade of events leading to transcription of a gene -Gain of function causes it to stay turned on w/o anything binding to it: constitutive activation -Dec. proliferation of chondrocytes and causes increased hypertrophy

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16
Q

allelic heterogeneity

A

-Different mutations in the same gene on different alleles causing same phenotype -beta thalacemia: different mutations occurring in one area which leads to beta thalacemia, can vary in severity depending on mutations in that area

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17
Q

locus heterogeneity

A
  • Different mutations on different genes causing same phenotype -ex: hypercholesterolemia: LDLr mutation and APOB (protein present on LDL that helps to bind to LDLR) mutation will both make elevated cholesterol level
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18
Q

clinical/phenotypic heterogeneity

A

-different mutations in same gene causing multiple phenotypes -beta thalassemia and sickle cell both affect the same gene on the same locus and result in diff phenotypes

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19
Q

alpha thalassemia -categorize what kind of mutation

A

-could be allelic heterogeneity (mult. Mutations in one alpha genes) or locus heterogeneity (two mutations located on both copies)

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20
Q

cystic fibrosis

A

-mutation of CFTR gene which produces CFTR protein which is a transport protein for chloride ion channel - expressed more in epithelial cells in digestive tract, bronchioles, sweat glands, tear producing gland - ex: of allelic heterogeinty b/c it’s mult. mutations in CFTR gene at single locus which leads to same phenotype expression

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21
Q

Domains of CFTR protein

A

-5 domains -#1-2 domains- transmembrane ion channels -NBD1: nucleotide binding domain; ATP binding spot -R domain: regulatory domain; regulates activity of whole protein -mutations in any of domains causes disease

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22
Q

Classes of mutations in cystic fibrosis (6)

A

1: absent transmembrane MSD1 protein; splice mutation of intron 4 donor site, 2: block in protein maturation; most common type, NBD1 doesnt fold properly so it does not function 3: defective gating; problem w/ closing of channel, NBD1 affected 4: defective conduction due to alteration of Cl channel; transmembrane MSD1 protein affected 5: reduced expression of CFTR gene; reduced amount of transcription, can be due to multiple causes 6: instability at the cell surface; Protein forms okay but when it gets into cell membrane then it is defective

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23
Q

Structure of adult hemoglobin

A
  • Has 4 subunits (2 alpha, 2 beta) - Forms globular protein, ex of Quaternary structured protein - A-H: alpha helices that make up beta globin chain - 2 a.a in hemoglobin, Histidine is linked to iron (ferris) which binds to oxygen; Phenylalanine helps porfirin rings to fit into pocket of globin
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24
Q

If there is mutation in histidine of hemoglobin

A

-will not bind to iron properly, less ability to carry oxygen

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25
Q

If there is mutation in phenylalanine of hemoglobin

A

-will not bind to heme properly

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26
Q

What are globins types in hemoglobin -chromosome -number of genes -total number of copies

A
  • 2 alpha; chromosome 16; 2 genes on each chromosome; 4 copies in total -2 beta; chromosome 11; one gene on each chromosome; 2 copies in total
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27
Q

zeta genes

A

-chromosome 16 -embryonic forms of alpha globin

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28
Q

epsilon gene

A

-chromosome 11 -embryonic form of beta globin

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29
Q

Hb A: -structure -expression

A

-2 alpha, 2 beta - At birth; Predominates after 6 mos of age

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30
Q

Hb A2 -structure -expression

A

-2 alpha, 2 delta -normally present in adult life but in very low amounts; high in B thalassemia

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31
Q

Hb F -structure -expression

A

-alpha 2, gamma 2 -fetal -Higher affinity for oxygen and can bind to maternal oxygen much more easily because there is decrease of 2, 3 BPG (bisphopshate glycerate) in fetal RBC, and 2,3 BPG cannot bind to fetal Hgb as easily as it does to adult Hgb

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32
Q

Hb M

A
  • Methomyoglobin - Reduced oxygen binding Modified variant of adult Hb (have ferric instead of ferris); His replaced by tyrosine
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33
Q

Thalacemia

A

-Imbalance of globin chain synthesis -deletion or extra copies due to unequal crossing over during homologous pairing

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34
Q

Genotypes and Phenotypes of alpha thalassemia -name -causes -how many copies -genotype

A

-Normal: contains all 4 copies; aa/aa -Silent carrier: contains 3 copies-only missing one; aa/a- -alpha thalassemia trait (mild anemia/ microcytosis): contains 2 copies;aa/– OR a-/a- -Hb H disease (moderately severe hemolytic anemia): contains 1 copy; a-/– -Hydrops fetalis: does not have any copies of gene; –/–

35
Q

Hb H disease (a-/–)

A

-lack of alpha chains forces beta chains to bind to each other; tetramer of beta chains -has high affinity but will not unload oxygen

36
Q

Mutations that cause beta thalacemia

A

-Splice site mutations: leads to B0 -Promoter mutations: mutation in TATA box leads to dec. in expression leading to B+ -Mutations in the 5’ cap: makes mRNAs unstable so there’s reduction in protein produced so leads to B+ -Nonsense mutations: mutations that changes a particular codon to a STOP codon which leads to B0 -Frame shift mutations: deletion or insertion of nucleotide which will lead to incorporation of STOP codon which leads to B0

37
Q

Classification of beta thalassemia

A

-minor; B/BO, silent -intermediate; B+/BO, moderate -major; BO/BO, severe

38
Q

Result of mutations in B globulin for beta thalacemia

A

-B0: minimum to no production of beta chain -B+: some production of beta chain in individual

39
Q

Signs and symptoms of beta thalacemia vs alpha thalacemia

A

-beta: symptoms will not show until later because fetus has gamma globulin instead of beta -alpha: will have symptoms from beginning because both the fetus and adult use alpha globulin

40
Q

Single gene inheritance

A

-One gene produces one protein -Can also lead to one gene causing one disease because one specific protein is affected

41
Q

Genetic diseases -most common -percentage of unknown causes of mutations

A

-congenital heart defects -80%

42
Q

Teratogens

A

stuff happens in utero-medications/drugs/ infections- that affect baby in utero and can cause mutations

43
Q

Infections that can cross placental barrier

A

○ Toxoplasmosis ○ Other: Zica (microcephaly) ○ Rubella ○ CytoMegaloVirus ○ Herpes, HIV Syphilis

44
Q

Multifactorial defects -prevalence

A

-more prevalent than single gene disorder -600 out of 1000 people have multifactorial disorder; not usually fatal

45
Q

Pedigree terms: -box/circle -Numbers at top -Blank box; colored box -half and half box - box or circle slashed - dot -two boxes come from same branch -P1 -F1

A
  • Box: male; circle: female - number of people in generation - blank: unaffected; colored: affected - half and half: carrier, may not show disease phenotypically -deceased -obligate carrier; have allele, will not show it phenotypically - twins; if boxes are connected (in triangle) they are monozygotic (come from same oocyte) if not connected they are dizygotic (fraternal; come from diff oocyte) - Parents (parental) - off spring (filial)
46
Q

Proband

A

first person from family to present to physician that they have the disease

47
Q

Consultant

A

Someone from family that believes their family may have a disease and asks geneticist to check

48
Q

Degree of separation

A
  • 1st- parents, siblings, children - 2nd- aunts, uncle, grandparents - 3rd- first cousins - 4th - first cousins once removed (1st cousins children)
49
Q

Relation between probands children and probands first cousins once removed (children of probands 1st cousin)

A

-second cousins

50
Q

Consanguity

A

inbreeding

51
Q

Modes of inheritance

A

-autosomal recessive -autosomal dominant -x-linked dominant -x-linked recessive -mitchondrial inheritance -pseudo autosomal

52
Q

autosomal recessive

A
  • Not sex cell -Need two copies of gene to manifest phenotype
53
Q

Autosomal dominant

A
  • Not sex cell -Need one copy of gene to manifest phenotype; in both homo and hetero
54
Q

X linked dominant

A

-Linked to x chromosome -X-linked activation: when one of x’s is turned off in females

55
Q

X linked recessive

A
  • Linked to x chromosome -both X’s have to have mutation
56
Q

Mitochondrial inheritance

A

Classically inherited from mother, more recently seen that it can be inherited from father

57
Q

Pseudo-autosomal

A

X-chromosome and y chromosome interlink and switch some information

58
Q

Cystic fibrosis -mode of inheritance -symptoms - Cl transport (acute vs chronic) -Pancreas (symptoms, treatment) -Variability in disease

A
  • Autosomal recessive - Clubbing of finger: bulbing at end, cyanotic color (blue): due to having chronic hypoxia - Cl transport is messed up in and out of cells, so surface of epithelial cells is more viscous and sticky (gunky, mucus build up) causes acute SOB or pneumonia, treatment: oxygen, antibiotics; chronically hypoxic -also has blocking of duct in exocrine pancreas, which is responsible for releasing digestive enzymes; lipase will then begin to destroy pancreas because it cannot be released into duodenum; symptom includes fat in stool; treatment: give patient pancreatic enzyme pills (pancrease) which allows for fat to be broken down, encourage low fat diet, supplement with fat soluble vitamins (A,D,E,K) - Allelic heterogeneity: Most severe form affects protein that is responsible for ATP binding; if mutation is outside ATP binding protein, then disease is not as severe
59
Q

Allelic heterogeneity

A

different mutations to same allele can cause varying degrees of the disease

60
Q

Neurofibromatosis -mode of inheritance -causes -symptoms on new born -severity -over time

A
  • autosomal dominant -neurofibromas: lumps and bumps grow on nerve fibers - On newborn baby, will present as multiple café-ole birthmarks (Need to ask parents if one of them had odd bumps/ spots that are similar) - Spots and bumps are progressive over lifetime - Can be mild, moderate, extremely severe
61
Q

Type II neurofibromatosis

A
  • grow on acoustic nerve only, presents with hearing problems–connected to entirely different gene than type I
62
Q

Deuchenne muscular dystrophy -mode of inheritance -caused by -signs and symptoms -testing -progressive

A

-x-linked recessive - Not enough dystrophin - Pelvic muscles first affected causes gowers sign and calf pseudohypertrophy of calves (big but non-functional) -elevated CPK in blood; muscle biopsy -will be in wheel chair by 5-6, eventually will need respirator, and will probably die of heart failure

63
Q

Incompletely dominant

A

-heterozygous produces a mixed phenotype -ex: red, white, and pink flower

64
Q

CoDominance

A

-heterozygous includes both phenotypes (AB) -Blood type, ABO

65
Q

Pleiotropy

A
  • One gene produces multiple phenotypes -Ex. Marfan syndrome
66
Q

Unstable repeat extension

A

-Genetic defect caused by repeating of AA in genes which extends with each generation it is passed down to - Anticipation: length of repeats elongates, which means over generations you will be affected sooner and more severely

67
Q

Insertion or Deletion -effect on genetic code -passed on?

A

-inserts or deletes a single or multiple nucleic acid from sequence -can get passed on if it does not change the fitness of a progeny

68
Q

Missense mutation

A

-codes for different AA

69
Q

Nonsense mutation

A

-will add stop codon, will shorten protein -protein may not be coded for because it is too small

70
Q

Polymorphism

A

Two or more common alleles (forms of gene) that have different sequence of nucleotides

71
Q

SNP -stands for -prevalence -used as?

A

-single nucleic polymorphism -single nucleotide change -everyone has them -can be used as markers

72
Q

Multi-factorial

A

mutations in multiple genes that can cause a disease

73
Q

Consensus Sequence

A

Most common sequence of a gene in the population

74
Q

What determines if gene acts in dominant or recessive way?

A

-Dominant: only needs one allele to be mutated in order for protein to show phenotype (not being functional) -Recessive: needs both alleles to be mutated in order for protein to show phenotype

75
Q

Does gene dosage matter?

A

yes/no -Yes; if you lose or gain an entire chromosome you are adding or deleting multiple proteins which can cause offspring to die or be in diseased state -No; one allele may be able to produce enough protein for the cell even though the second allele cannot produce a functional protein

76
Q

Kinds of defects in CTFR? -type; and effect -most common?

A
  • Nonsense mutation; protein would not be synthesized - Misfolding; protein will not make it out of ER - Reduced number of transcripts of gene; not making enough copies of gene - CFTR will not open -Class 2 is most common in cystic fibrosis; delta F508
77
Q

Class of inheritance for cystic fibrosis?

A

autosomal recessive

78
Q

Diagnosing CF

A

Some patients can have some residual secretion of Cl and if there is enough secretion then the diseased state may not present until there is insult from environment OR will present as very mild symptoms so correctly dx as cystic fibrosis would be hard if genetics were unknown

79
Q

Men and CF

A

fathers should not have the disease because then they wont be able to have children due to vas defrens not working

80
Q

Hardy Weinberg Equation

A

P2+2PQ+Q2=1 P: dominant Q: recessive

81
Q

Multi-factorial disorders -involve?

A

-genetic contribution -environmental contribution (modifiable vs non-modifiable)

82
Q

Examples of multi-factorial disorders

A

-ASCAD: -Daibetes

83
Q

CFTR mutations

A
  • Class I: frame shift,nonsense on MSD1, absent protein
  • Class II: missense mutation on NBD1, CFTR mis-folded and nonfuction so degraded in the RER
  • Class III: missense mutation on NBD1, defective gating, problem w/ closing of channel
  • Class IV: missense mutation on MSD1, reduced channel conductance
  • Class V: splicing defect on MSD1, reduced CFTR synthesis
  • Class VI: missense mutation, decreased CFTR stability
84
Q

Hard-weinberg law assumption

A

-large population (USA) -random selection (Trump as president) -no significant immigration (Trump) -no new mutations (racist) -random mating (racist)

Unit 3: LGS (7 decks)

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