Extensions to Mendel's Rules (Lec 6 & 7) Flashcards

1
Q

What is it called when the phenotype of the heterozygote is the same as the phenotype of one of the homozygotes

A

dominance

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2
Q

True or False?

Cystic Fibrosis is considered to be a recessive disease.

A

true

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3
Q

In cystic Fibrosis mutated form of CFTR causes channels to remain closed and this ion remains within cells

A

Cl-

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4
Q

In regards to Cystic Fibrosis, heterozygotes produce both normal and mutated CFTR at the cellular level, this can be considered what? At the phenotypic level it can be considered what?

A

co-dominance; normal

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5
Q

What is it called when the phenotype of the heterozygote is intermediate between the phenotypes of the two homozygotes?

A

incomplete dominance

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6
Q

What is it called when the phenotype of the heterozygote includes the phenotypes of both the homozygotes?

A

co-dominance

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7
Q

What is penetrance?

A

percentage of individuals having a specific genotype that express the expected phenotype

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8
Q

What is expressitivity?

A

the degree to which a character is expressed

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9
Q

Type O blood carriers are called what? Type AB?

A

Type O - universal donor

Type AB - universal recipient

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10
Q

The masking of one gene by another gene at a different locus is called what?

A

epistasis

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11
Q

The epistatic gene is the gene that does what?

A

masks the other gene

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12
Q

The hypostatic gene is the gene that does what?

A

gets masked

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13
Q

What is dominant epistasis?

A

homozygous dominant or heterozygous genotypes mask the effects of the hypostatic gene

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14
Q

What is recessive epistasis?

A

presence of either of two homozygous recessive genotypes will mask the hypostatic gene

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15
Q

What does a 9:3:4 phenotypic ratio indicate?

A

recessive epistasis

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16
Q

what does a 12:3:1 phenotypic ratio indicate?

A

dominant epistasis

17
Q

What does a 9:7 phenotypic ratio indicate

A

duplicative recessive epistasis

18
Q

What does a 15:1 phenotypic ratio indicate?

A

duplicative dominant epistasis

19
Q

When does complementation occur?

A

when an individual organism possessing two recessive mutations has a wild-type phenotype

20
Q

What are sex-infuenced characteristics determined by?

A

autosomal genes

21
Q

How much penetrance do sex-limited characteristics (also determined by autosomes) have in the opposite sex?

22
Q

What are some characteristics of cytoplasmically inherited traits?

A

present in males and females, usually inherited from one parent (usually the maternal parent), reciprocal crosses give different results, exhibit extensive phenotypic variation

23
Q

What is the genetic maternal effect?

A

phenotype of the offspring is determined by the genotype of the mother

24
Q

Differential expression depending on whether it is inherited from the male or the female parent is called what?

A

genomic imprinting

note: due to DNA methylation differences in sperm and eggs

25
What are characteristics of Prader-Willi Syndrome?
small hands and feet, short stature, poor sexual development, mental retardation, voracious appetites, mutation is always inherited from father
26
What are characteristics of Angelman Syndrome?
exhibit frequent laughter, uncontrolled muscle movement, large mouth, unusual seizures, mutation is always inherited from mother
27
The phenotype of a sex-linked characteristic is determined by what?
genes located on the sex chromosome
28
What are discontinous characteristics?
characteristics with only a few easily distinguishable phenotypes ex: tall pea plant vs short pea plant
29
What are continuous characteristics?
characteristics characterized by a continuous distribution of phenotypes; often polygenic ex: human height/weight
30
Characteristics encoded by genes at multiple loci are called what?
polygenic characteristics ex: kernel color in wheat
31
Characteristics that are polygenic and also influenced by environmental factors are called what?
multifactorial characteristics ex: human intelligence
32
Define pleiotropy
one gene affects multiple characteristics ex: lethal allele for yellow coat color in mice
33
What is the phenomenon in which a genetic trait becomes more strongly expressed and/or is expressed at an earlier age in succeeding generations?
anticipation ex: huntington's disease, fragile-x syndrome