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Cell and Molecular Biology > Developmental Genetics + Clinical Genetics + Genetic variations > Flashcards

Developmental Genetics + Clinical Genetics + Genetic variations Flashcards

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AP® Biology flashcards Biology 101 flashcards
1
Q

Structural variation vs substitution variation

A

Structural: In/dels

Substitution: SNPs

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2
Q

Common vs Rare variant

A

Common: both alleles @ +1% frequency

Rare: allele present @ less than 1% frequency

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3
Q

SNP definition

A

Less common allele of a single nucleotide substituition is present @ +1%

Usually bi-allelic

If muation is in coding region, usually silent or conservative missense

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4
Q

Sickle cell anemia mutation

A

Glu6 >> Val6 (missense)

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5
Q

Beta thalassemia mutation

A

Glu6>>STOP (nonsense)

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6
Q

Non coding region mutations can occur in __, __ and ___.

Give 2 examples of this

A

Promoter, enhancer/silencer, 5’ and 3’ UTR

Beta thalassemia mutation in promoter region

Repeats in CFTR gene (Intron 8)

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7
Q

Structural variants: What are the 2 ways you could get CF?

A

Phenylalanine deletion at position 508

(TG)n(T)n repeats in Intron 8 >> exon exclusion of Exon 9

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8
Q

How do repeats that cause Huntington’s disease and Fragile X syndrome vary in terms of phenotype + which repeat? (HD)

A

HD: CAG repeat

Fragile X: CGG

HD: CAG repeats in ORF; more repeats = earlier age of onset

Fragile X: repeats in 5’ UTR = loss of function

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9
Q

Fragile X repeat phenotype

A
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10
Q

Copy number variants: what’s the effect of a mutation in the AMY (amylase) gene?

A

More copies = faster carbohydrate breakdown + improved glycemic homeostasis/decreased diabetes risk

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11
Q

Use alpha thalassemia to explain copy number variations

A

Repeats can become misaligned, results vary based on mutation (nonsense >> 1/2 normal, missense >> 1/4 normal)

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12
Q

How does an inversion cause hemophilia?

A

Mispairing of similar factor 8 sequences

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13
Q

Genotype and phenotype correlation:Osteogenesis imperfecta (what’s the effect of a missense vs a nonsense mutation?)

A

Missense: 1/4 normal

Nonsense: 1/2 normal

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14
Q

What is a frameshift mutation?

A

Frameshift is an inserted or deleted fragment that is not divisible by 3

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15
Q

Explain why a deletion of Exon 45 in the DMD gene would lead to classical DMD but a deletion in a larger fragment will lead to Becker’s Muscular Dystrophy (a much milder disease)

A

The DMD gene is such that each segment contributes to a protein that on the whole will act as a shock absorber (a lot of individual components lined together). A del in Exon 45 (total number of genes NOT divisible by 3) will disrupt the remainder of the gene, thereby destabilizing all the other pieces of the protein/shock absorber. A del in a larger chunk of genetic material, however, would cause less damage b/c the remaining exons would still be translated to functional pieces of the shock absorber thus some function would be retained.

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16
Q

Disease associated (susceptibility) variants:

The MATP gene codes for ___. A mutation in this gene could lead to ___, resulting in___.

A

Melanin production.

Lighter skin.

Vitamin D deficiency/Malignant malinoma

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17
Q

A lower copy number of an AMY mutation could lead to___

A

Increased predisposition to obesity

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18
Q

Malformation definition

A

Damage that results from intrinsic GENETIC abnormalities

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19
Q

Major malformation

A

If uncorrected/incorrectable, defect impairs normal function/reduces life expectancy

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20
Q

Minor malformation

A

Defect that is of mostly cosmetic significance

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21
Q

Major malfomation examples

A

NTDs

cleft lip +/- palate

Brachydactyly

Fetal alcohol syndrome

Trisomy 13

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22
Q

Fetal alcohol syndrome cause + symptoms

A

Cause - Teratogen

Symptoms -

Thin upper lip

Growth retardation

Learning disabilities

Smooth philtrum

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23
Q

Cleft lip +/+ palate characteristics

A

More common in males than females

Usually isolated

One of the most common multifactorial birth defects

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24
Q

Cleft palate

A

More common in females more than males

Usually syndrome-associated

Not as common

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25
Q

Isolated malformation

A

Restricted to one part of the body

26
Q

What are the risks of having 3+ minor malformations?

A

Increased chance of dysmorphic syndrome

Increased risk of major malformation

27
Q

Syndrome definition

A

Condition in which one causative agent affects multiple organ systems simultaneously

OR

Pattern of malformations that either are or have to be etiologically related

28
Q

Waadernburg syndrome characteristics + symptoms

A

Cause: Type I and 3 = Pax3 mutation (NC cells); Type 2 = MitF mutation (melanocytes)

Phenotype: Skin pigmentation issues

Pale eyes

White patch of hair

+ Upper limb abnormalities if Type 3

+ Hearing loss if Type 2

29
Q

Sequence definition

A

Chain of developmental malformations (one leads to the other) resulting from single causative agent

30
Q

Pierre-Robin sequence

A

“The small chin baby”

Small mandible

Tongue pushed back

U shaped cleft palate

31
Q

Association definition

A

Non-random occurence of multiple congenital abnormalities not known to be a sequence or syndrome

32
Q

VACTERL association

A

Vertebral

Anal

Cardiac

Tracheo-Esophageal

Renal

Limb

33
Q

CHARGE association/syndrome

A

Coloboma (of eye)

Heart defect

Atresia

Retardation of growth

Genital anomalies

Ear anomalies

34
Q

Deformation

A

Damage to a part of the body that would’ve otherwise formed normally; Due to external force

e.g. Breech deformation

Can be combined with NTD (e.g. omphalocele w/ club foot)

35
Q

Disruption

A

Destruction of part of the body that would’ve developed normally

e.g. Amniotic bands

36
Q

Pleiotropy

A

Single causative agent affects more than one organ system

Syndrome or sequence

37
Q

Teratogen

A

Transient effect, no change in dna therefore damage is not heritable, direct impact of fetus

38
Q

Mutagens

A

Change in DNA therefore heritable

39
Q

Less restricted cell fate

A

Pluripotent stage (cell can become whatever)

40
Q

More restricted cell fate

A

Approaching or at terminal differentiation (basically cell can’t become much else)

41
Q

Specification/Differentiation

A

Characteristics of cell still changeable in response to environmental cues (basically, less-restricted cell type kinda thing)

42
Q

Determination

A

Basically cell = terminally differentiated

43
Q

Factors controlling cell fate

A

Too Much Information

Transcription factors

Morphogens

Induction

44
Q

Transcription factors and functions (3)

A

MyoD (myoblasts>>myocytes)

Pax3 - “Pax of NiCotine” - differentiation of neural crest cells

Hox - axis specification and limb development

45
Q

How do Hox genes work? (say it out)

Which end of a Hox gene cluster (3’ vs 5’) codes gives rise to proximal/anterior and distal/posterior?

A
46
Q

What results from a mutation in HoxD13?

What kind of mutation is this?

A

Synpolydactyly

Gain of function

47
Q

What is a morphogen and how does it affect development?

What is an example of a morphogen and its source?

A

Diffusible signal that acts a distance; concentration varies by distance from the source

Sonic Hedge Hog (SHH) and the Zone of Polarizing Activity

48
Q

What is the effect of a high SHH concentration vs low SHH concentration (as measured by distance from the ZPA)?

A

High SHH = posterior

Low SHH = anterior

49
Q

Explain how the absence of SHH affects the GLI transcription factors, and the transcription of SHH responsive genes

A

No SHH = PTCH1 receptor inhibits SMO

SMO cannot inhibit PKA, which will add (P) GLI1-3 complex

Phosphorylated GLIs acts as repressors of SHH responsive genes

50
Q

Explain how the presence of SHH affects the GLI transcription factors and transcription of SHH responsive genes

A

SHH binds to PTCH1 receptor>> SMO no longer inhibited

SMO inhibits PKA >> GLI proteins NOT phosphorylated

Unphosphorylated GLI proteins now active and act as activators for SHH responsive genes

51
Q

What ultimately determines cell fate through the action of SHH?

A

The ratio of the concentration of GLI activator/GLI repressor

52
Q

Holoprosencephaly (causes + symptoms)

A

Mutation in SHH

Cleft lip + palate

Midline single central incisor (if mild)

Hypotelorism

Microcephaly

53
Q

What disease results from a mutation in GLI3?

A

GCPS (Greig’s cephalopolysyndactyly)/Pallister Hall syndrome

Defects in:

Limbs

Craniofacial

Nervous system

Airway

Genitourinary

54
Q

A disease characterized by GCPS combined with dental cysts and basal carcinoma is likely due to a mutation in the ___ receptor of the SHH signaling pathway

A

PTCH1

55
Q

A mutation in a coactivator of GLI3 results in ___, which is characterized by a broad thumb as well as ___.

What is the name of the coactivator?

A

Facial abnormalities

Hand abnormalities (broad thumb)

Mental retardation

Congenital HD

CREB-binding protein

56
Q

Describe the process of induction using the role of FGF8 and Pax6 in lens development as an example

A

A signal from one region of embryonic development influences the cells in another region, therefore the fate of those cells is “induced” by that signal

57
Q

A ___ mutation in the core promoter of the Beta-globin gene results in ___

A

Beta thalassemia

58
Q

Preaxial polydactyly arises from a mutation in the ___ element, an ___, of the SHH gene

A

“Enhancing SHH’s ZRS (pronounced scissors) gives you too many fingers”

ZRS element

59
Q

A ___ mutation, specifically that of ___ repeats in the DUX4 gene leads to __-__-__ dystrophy

A

“D4Z4 is silent b/s his FACE, SCAPULA and HUMERUS are weak

60
Q

Treacher Collins syndrome results from a mutation in the ___ site of the ___ gene

A

YY1 binding site (activator)

TCOF1

61
Q

Achondroplasia results from a mutation in the ___ gene. What is the effect of this mutation such that it leads to disease?

A

FGFR3 (G380R)

Mutation results in constitutively active Tyrosine Kinase (constant negative regulation of long bone growth)

Cell and Molecular Biology (7 decks)

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