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ALL THE THINGS Flashcards

1
Q

What is a phenotype?

A

observable characteristic of a person

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2
Q

What is a genotype?

A

genetic information of an organism. The DNA SEQUENCE

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3
Q

What are genes and what do they encode?

A

unit of hereditary information

functional product - protein or RNA

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4
Q

What is an allele?

A

variant form of a gene

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5
Q

What genotype parents did Mendel cross for his F1 generation?

A

Purebred (TT x tt)

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6
Q

What was the result of Mendel’s F1 cross?

A

All heterozygous offspring (Tt)

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7
Q

What genotypes did Mendel cross for his F2 cross?

A

Tt x Tt

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8
Q

What were the genotypic and phenotypic ratios that Mendel saw after his F2 cross?

A

1 TT : 2 Tt : 1 tt (Geno)

3 (TT, Tt Tt) : 1 (tt) (Pheno)

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9
Q

What are Mendel’s Laws?

A

Dominance (Uniformity)

Segregation

Independent Assortment

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10
Q

What is the law of Dominance?

A

crossing two homozygotes with different alleles yields identical F1 offsping - All Heterozygotes

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11
Q

What is the law of Segregation?

A

Each individual carries two genes for a characteristic but only on is passed on to the next generation at each mating

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12
Q

What is the law of Independent Assortment?

A

Members of different gene pairs segregate to offspring independently of each other

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13
Q

The human genome is made up what two types of DNA?

A

nuclear and mitochondrial DNA

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14
Q

What is the shape of mitochondrial DNA?

A

circular

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15
Q

Are there multiple copies of the mitochondrial DNA per mitochondrion?

A

Yes - > 1000 copies per cell

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16
Q

How many genes present in the mitochondrial genome?

A

37 genes

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17
Q

What are the mitochondrial genes involved in?

A

ETC and Oxidative phosphorylation

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18
Q

Are there histones in the Mitochondrial genome?

A

NO!

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19
Q

How is mitochondrial DNA inherited?

A

Maternally

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20
Q

In a pedigree, who is the Proband?

A

The member through whom a family with a genetic disorder is first brought to attention

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21
Q

Is the Proband usually a patient?

A

Yes, but could be any family member

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22
Q

Who is the Consultand?

A

an unaffected individual seeking counseling - can also be the proband

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23
Q

Examples of first degree relationships

A

parent, sib, child

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24
Q

% of genes common in first degree relationships

A

50%

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25
Examples of second degree family relationships
aunt, uncle, niece, nephew, etc.
26
% of genes common in second degree relationships
25%
27
Example of third degree family relationships
first cousins
28
% genes common in third degree family relationships
12.5%
29
Case 1 of Huntington Disease Characteristics
pt was forgetful, depresed, restless. Had choreiform movements and family history of presentation.
30
What % chance does one affected parent have to transmit the phenotype to each offspring in AD inheritance?
50%
31
Are successive generations affected in AD inheritance?
Yes, no skipping of generations
32
What transmission pattern is observed in AD inheritance?
Vertical transmission
33
Are males and females affected equally in AD inheritance?
Yes
34
Is there Male to Male transmission in AD inheritance?
Yes!
35
Where would a spontaneous mutation occur in a family presenting AD inheritance out of nowhere in a pedigree?
In the meiosis of one of the parents
36
Since AD diseases are selected against, what is the obvious explanation for a pedigree with an out of the blue occurrence of an AD disorder?
Spontaneous Mutation
37
Is it likely that siblings in a case of spontaneous mutation for AD inheritance will be affected?
Possible, but unlikely
38
What are the common AD inheritance disorders?
``` Huntington Disease Marfan Syndrome Achondroplasia Osteogenesis Imperfecta Neurofibromatosis ADPKD ```
39
What can create the appearance of skipped generations in AD inheritance pedigrees?
Incomplete penetrance
40
What is penetrance?
Probability thatindividuals with a specific genotype will manifest the corresponding phenotype.
41
What kind of measure is Penetrance?
All or none and severity is not considered
42
What is incomplete penetrance?
Some individuals with a genotype do not manifest the corresponding phenotype.
43
What is variable expressivity?
variation in phenotype amongst individuals carrying the same genotype. Variations observed in symptoms and severity
44
Case 2 Cystic Fibrosis characteristics
confirmed with sweat test. lung disease, lung infections, malabsorption, salty sweat, male infertility, meconium ileum
45
If both parents are carriers, what % chance do they have of having an affected child under AR inheritance?
25%
46
What kind of pattern is observed in AR inheritance pedigrees?
Horizontal pattern. disorder occurs in one generation typically.
47
Can siblings be affected in AR inheritance?
Yes.
48
Is there vertical transmission in AR inheritance?
Possible, but rare.
49
Are males and female affected in AR inheritance?
Yes
50
Is there male to male transmission in AR inheritance?
Yes.
51
In AR mating, do both parent have to carriers?
YES!
52
Examples of AR inheritance diseases
Metabolic disorders (Enzyme issues) - Alkaptoneuria, PKU, etc. Cystic Fibrosis Thalassemias Sickle Cell Disease
53
Case 3 Characteristics
Parents were first cousins and had a child who was normal but had profound bilateral hearing loss
54
What are consanguineous matings?
matings between individuals who are 5th degree (or closer) relatives. Second cousins or closer.
55
In consanguineous matings, the closer the degree of relationship, the more ---
likely an AR phenotype will be expressed
56
What is Pseudodominance?
recessive trait mimics dominant pattern. Multiple generations affected
57
What is Complementation?
mating between individuals with the same phenotype results in offspring without the phenotype. Phenotype due to mutations in different genes results in heterozygous offspring
58
2/3 Rule
traits inherited in an AR manner, an unaffected sibling of an affected individual has a 2/3 risk of being a carrier
59
Case 4 Characteristics
son of normal parents. delayed motor milestones. Uses Gower's maneuver to rise. Maternal history of DMD
60
Are females affected in XR inheritance?
Few (if any). Males affected in multiple generations
61
Is there male to male transmission in XR inheritance?
NO!
62
If a mother is a carrier for XR disease ---
50% of her daughters are carriers 50% of her sons are affected
63
If a father is affected with a XR disease ---
0% of his sons are affected 100% of his daughters are carriers
64
Who are obligate carriers?
individuals who must be carriers based on logical pedigree analysis
65
If you see an isolated case of XR disease it may be due to ---
Spontaneous mutation. Not safe to assume mother is a carrier
66
Examples of XR disorders
DMD Hemophilia Red-green color blindness
67
Is there male to male transmission in XD inheritance?
NO!
68
Which sex is affected twice as much in XD inheritance?
Females
69
Affected mothers with XD disorder will have ---
50% daughters that are affected 50% sons that are affected
70
Affected fathers with XD disorder will have ---
None of his sons affected 100% of daughters are affected
71
Example of XD disorders
Rett Syndrome Fragile X Syndrome
72
Case 6 Characteristics
blurred vision and loss of color distinction. Parents are healthy but maternal uncle and aunt are blind or have impaired vision. suspect LHON
73
In mito inheritance, how are the disorders inherited by offspring?
Maternally
74
Children of affected mito disorder males are ---
never affected
75
Children of affected mito disorder females are ---
always affected (except with reduced penetrance)
76
Describe a person expressing a mosaic
individual who's body contains two or more genetically distinct cell lines
77
Where do situations of mosaicism occur?
due to mutations occurring post - fertilization. The sooner the mutation occurs post fertilization, the more cells will be affected
78
What are the two types of mosaicism?
Somatic and Germline
79
Describe Germline mosaicism
mutation exists in the germline. Can be passed to offspring
80
Describe somatic mosaicism
Mutation does not occur in the germline but may occur in other tissues. Can't be passe to offspring

INHERITANCE PATTERNS (1 decks)

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