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34 Cards in this Set
- Front
- Back
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1. What is a nucleotide?
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1. Sugar
2. Phosphate 3. Base **have 4 bases (A, C, G, T -- U in RNA) |
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2. What happens to the nucleotide?
What does nucleotide order give? What is a gene? What do genes create? |
Nucleotide is transcribed to get RNA
Nucleotide order gives information Gene is the functional unit of heredity One gene can create hundreds of proteins **depends on what happens to extrons |
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3. What are the components of a gene?
Three parts... |
1. Promoter region
2. Exon(s) 3. Intron(s) |
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4. What occurs during transcription?
Where does transcription occur? |
DNA is copied to RNA
**still have introns and exons In nucleus |
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5. What happens during RNA splicing?
What is translated into proteins? Where does translation occur? |
Introns are removed
Exons are translated into proteins Translation occurs at ribosomes |
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6. How much DNA is in a single cell?
How is DNA organized? |
2 meters of DNA in a single cell
(lot of chromatin) 1. DNA 2. Nucleosome 3. Fiber 4. Loop 5. Condensed 6. Chromosome |
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7. What is DNA?
What is a nucleosome? How is the chromosome? |
DNA is unwound double helix chromatin
Nucleosome is a histone protein around which DNA wraps Chromosome is the replicated form that is ready to divide |
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8. Why is the upper 5' to 3' sequence of DNA important?
What is an allele? What does a change in an allele produce? |
Important b/c it's the sequence that is transcribed
Unit of inheritance Produces a change in phenotype |
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9. What are six types of genetic variation?
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1. Base pair substitution
2. Small insertions or deletions of DNA 3. DNA sequence rearrangement 4. Gene insertions or deletions 5. Copy number variation 6. Chromosomal changes |
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10. What are SNP's?
What causes clinical problems? |
Single Nucleotide Polymorphism
**base pair substitution Mutations cause a clinical problem **variants do not |
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11. What is autosomal dominant inheritance?
Affected parents have what percent chance of having an affected child? |
One affected allele results in clinical phenotype
50% change of having affected child |
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12. What is autosomal recessive inheritance?
Two carrier parents have what percent chance of having an affected child? Normal siblings have what percent chance of being a carrier? |
Two affected alleles result in clinical phenotype
25% chance of having affected child 2/3 chance of being a carrier |
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13. What is the most common Mendelain cleft lip and palate?
What four clinical features do affected individuals have some or all of? |
Van der Woude Syndrome (VDWS)
1. Cleft lip with or without cleft palate *unilater/complete 2. Cleft palate w/o cleft lip 3. Hypo- or oligodontia 4. Lower lip pits |
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14. What type of inheritance is Van der Woude Syndrome?
Is it common? How is it's penetrance? What is penetrate? How is expressivity of VDWS? |
Autosomal dominant
*mutations in IRF 6 cause VDWS Rare (1 / 100,000) Highly penetrant If get allele you will show phenotype Variable expressivity (syndromic) **great variability in what phenotype looks like |
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15. What are examples of complex inheritance?
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1. Family clustering
2. Twin studies 3. Polygenic / Multifactorial inheritance 4. Multifactorial Threshold Model 5. Nonsyndromic Cleft Lip and/or Palate |
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16. What is penetrance?
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Describes the proportion of individuals carrying a particular variation of a gene (an allele or genotype) that also express an associated trait (the phenotype)
**If you get allele it's the likelihood you will show phenotype |
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17. What is expressivity?
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Refers to variations of a phenotype in individuals carrying a particular genotype
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18. What are twin studies important?
In monozygotic twins (MZ) what are differences due only to? In dizygotic (DZ - fraternal) twins what are differences due to? |
Help disentangle genetic and environmental factors/influences
MZ twins -- only environment **share 100% gene DZ twins -- genes & environment **share 50% genes (like siblings) |
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19. What is concordance?
What is discordance? |
Occurrence of a trait in both twins
Occurrence of a trait in one twin |
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20. In Mendelian disease what is concordance for MZ and DZ twins?
In complex disease if MZ twins have less than 100% concordance what is it due to? If MZ concordance is greater than DZ concordance for complex disease than which has a greater role genes or environment? |
MZ twins --> 100% concordance
DZ twins --> 50% concordance (AD) (25% concordance if AR) Environment Genes |
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21. Based on concordance rates what is spina bifida and autism more likely due to genes or environment?
What about measles and why? |
Genetics
Environment b/c both MZ and DZ have a high concordance rate |
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22. What is height?
What is the polgenic inheritance of height? |
Polygenic (many genes)
Many genes, each with 2 alleles Each tall allele adds 1 cm no matter which gene it is from |
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23. What is multifactorial inheritance?
How are the traits measured? What are some continuous traits? |
Multifactorial means it's both polygenic and environment
Developed for quantitative traits Traits are measured on a continuous scale Height, blood pressure, IQ |
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24. What is the Multifactorial Threshold (MFT) model?
What does type of trait does the threshold create? |
In the MFT model, genes contribute an underlying liability
Get to risk threshold --> breach it --> get phenotype Creates a discontinuous (dichotomous) trait |
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25. In the MFT model what is the proband?
What three things will cause the recurrence risk to increase in the MFT model? What causes the recurrence risk to decrease rapidly? |
First identified person in family with disease
1. Number of affected increases 2. Proband in severely ill 3. Proband is from less frequently affected sex Decreases rapidly in more distant relatives |
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26. In orofacial clefting what are most cleft lip and palates?
What are about half the clef palates alone? In terms of range of severity what percent are unilateral CL/P? |
Non-syndromic
Non-syndromic **CP only is half as common as CL/P) 80% unilateral (70% left) |
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27. Which is more severe unilateral or bilateral CL/P?
Which sex is affected more? |
Bilateral is more severe
More males affected with bilateral CL/P **CL alone: 1.5M : 1F **CL/P: 2M: 1F |
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28. Which sex is affected more with bilateral CP only?
What do 1/80 US Caucasians have? |
More females than males with bilateral CP only
Cleft uvula |
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29. According to twin studies of CL/P what are the concordance rates for MZ twins and DZ twins?
What percent of CL/P cases are sporadic? |
MZ twins --> 40% concordance (environment)
DZ twins --> 4% concordance **genes have a minor role 50% - 75% of CL/P cases are sporadic |
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30. What is the recurrence risks to relatives of a CL/P individual if...
1. Sibling is affected 2. Two affected siblings or one affected parent and sibling 3. Two affected parents? |
1. Siblings --> 4%
(any 1st degree relative 3%) 2. 9% 3. Two affected parents --> 25% |
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31. What is the genetics of non-syndromic CL/P?
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Familial / Complex
**not Mendelian Involves 3 -14 genes |
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32. What increases liability to CL/P?
What are some additional risk factors? |
IRF6 (single variability)
**12% 1. FGFs (3%) 2. MSX1 (2%) 3. Private mutations (6%) 4. Material smoking -4% unilateral -12% bilateral |
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33. What are clefts?
What is the primary palate? What is the secondary palate? |
Lack of suture development
Pre-maxilla Cuspids and posterior teeth |
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34. What is premature suture fusion mediated by?
What is an example of this? |
Mediate by transcription factor mutations
Interferon Regulator Factor (IRF) 6 |
