Genetics I and II Flashcards

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1
Q

Mendel’s first law

A

The principle of segregation, meaning two members of a gene pair segregate from each other in the formation of gametes> Half of the gametes carry one allele and the other half carry the other allele.

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2
Q

Mendel’s second law

A

The principle of independent assortment meaning genes for different traits assort independently of one another in the formation of gametes.

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3
Q

What is a compound heterozygote?

A

A genotype in which two different mutant alleles of the same gene are present rather than one mutant and one normal

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4
Q

What is hemizygosity?

A

A male that has an abnormal alleles for a gene located on the X-chromosome and there is not other copy of the gene

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5
Q

In pedigrees, what does kindred mean?

A

Extended family depicted in pedigrees

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6
Q

What is a pro band?

A

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

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7
Q

What is the consultand?

A

The person who brings the family to the attention of the geneticist

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8
Q

Who is the first degree of a pedigree?

A

Parents and sibs of offspring and proband

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9
Q

Who is the second degree of a pedigree?

A

Grandparents and grandchildren, uncles and aunts, nephew and nieces and half sibs

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10
Q

Who is the third degree of a pedigree?

A

First cousins

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11
Q

Most recessive disorders are due to ________

A

Loss of function

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12
Q

What is penetrance?

A

Percentage of people with a predispositioning genotype who are actually affected, at least to some degree; can be age dependent

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13
Q

What is expressivity?

A

Severity of expression of the phenotypes among individuals with the same disease causing genotypes.

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14
Q

There are three types of heterogeneity, what are they?

A

Allelic heterogeneity, Locus heterogeneity, and phenotypic heterogeneity

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15
Q

Genome mutations produce _________ and are the most common mutations in humans

A

Chromosomal aneuploidy

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16
Q

Chromosomal mutations are usually ___________

A

Not compatible with life

17
Q

Gene mutations can be caused by two mechanisms, _________ or ____________

A
  1. Errors introduced during the normal process of DNA replication 2. Mutation arising from a failure to repair DNA
18
Q

Dynamic mutations such as Huntington disease or fragile X syndrome involve ___________

A

Amplification of trinucleotide repeats sequence

19
Q

The longer oocytes remain in meiosis I, the greater the chance for _________ to occur when the cells finally complete meiosis.

A

Nondisjunction error

20
Q

_______________ are common in sperm

A

Point mutations that usually cause missense mutations

21
Q

Huntington’s disease is a _____________ of paternal order

A

Trinucleotide repeat disorder

22
Q

In _________, there are massive expands in the CGG repeat region and nearly always occurs during female gametogensis

A

Fragile X

23
Q

Genetic Polymorphism occurs when a variant is so common that it is found in ___________

A

1% of chromosomes

24
Q

Alleles with frequencies less than 1% are called _________

A

Rare Variants

25
Q

The Hardy-Weinberg Law is a relationship for calculating ________ from __________

A

Genotype frequencies from allele frequencies

26
Q

For x-linked genes, there are only two possible _______ but three ___________

A

Male genotypes; famale genotypes

27
Q

Assumptions of HW equilibrium (3)

A
  1. Population in large 2. Mating is random 3. Allele frequencies are not changing over time
28
Q

Non-random mating could be due to three factors. What are they?

A
  1. Stratification 2. Assortative mating 3. Consanguinity
29
Q

_________ occurs in small populations

A

Genetic drift

30
Q

Most deleterious recessive alleles are hidden in heterozygotes and ____________

A

Not subject to selection

31
Q

What is the founder effect?

A

When a small subpopulation breaks off from a larger population and may not have the same genetic frequencies as the parent group.

32
Q

For both hemophilia A and B, the level of _____ and _____ activity predict the clinical severity.

A

Factor VIII and IX

33
Q

Point mutations and the common F8 inversions almost always arise in male meiosis and therefore, mother carriers get it from a new mutation from their _________

A

Father