Complex Inheritance Patterns Flashcards

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1
Q

what is Mendel’s rules correct for? what don’t they work for?

A

correct for predicting genotype, but no for most phenotypes and traits

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2
Q

define incomplete dominance

A

where neither allele completely dominates and you get a “blended” phenotype

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3
Q

what does incomplete dominance reflect the importance of?

A

important of gene dosage in creating most phenotypes

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4
Q

describe multiallelic genes

A

for most genes in diverse populations, there are almost always more than just two alleles

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5
Q

example of multiallelic gene

A

tyrosinase- a tissue specific effector gene that encodes an enzyme required for melanin synthesis (there are 102 functional mutations - phenotypic alleles - of the mouse tyrosinase gene in exons and CREs

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6
Q

describe pleiotropic genes, what rule does it defy?

A

mutations in a single gene affects many “traits”, defies the “one gene, one trait” rule

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7
Q

describe continuous phenotypic variation

A

very few traits are “binary” like simple mendelian genetic diseases, most phenotypes fall on a broad spectrum

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8
Q

potential causes of continuous phenotypic variation

A

1) CRE mutations that create partial LOF or GOF alleles with slight more/less expression
2) mulitgenic traits where several genes add together to give phenotype
3) environment contributes to variation

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9
Q

example of “multigenic trait”

A

height- multiple intercellular signaling receptors/ligands, T.F.s and tissue specific effector genes work together to determine height

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10
Q

the only “exception” to Mendel’s rules relating to genotype and alleles

A

genetic linkage, genes are not physically independent particles

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11
Q

what does genetic linkage predict? who observed this?

A

predicts that certain phenotypes will tend to appear together, Thomas Hunt Morgan saw linkage using vinegar flies (probably because he looked at many more traits than Mendel)

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12
Q

why does genetic linkage happen?

A

genes can be physically linked on chromosomes and as a result, alleles and phenotypes can co-segregate

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13
Q

linkage in practical terms

A

phenotypes for body color, eye color, and wing shape would usually occur together and defy independent assortment ratios seen by Mendel

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14
Q

why is linkage not usually complete?

A

because crossing over can “unlink” alleles & the further apart two genes are on a chromosome, the higher the odds of crossing over happening between them and then they behave more like “independently assorting” particles predicted by Mendel

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15
Q

describe sex determination

A

whether germline cells differentiate into eggs, sperm, both or neither

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16
Q

define anisogamous

A

meaning they have gametes of different sizes and morphology

17
Q

define isogamous

A

there is only one type of gamete

18
Q

define agamous

A

never go through meiosis, reproduce by budding or fragmentation

19
Q

how do different tissue-specific effector genes become activated in germline cells?

A

same way as usual development, different combos of T.F.s activate tissue-specific effector genes to differentiate eggs vs sperm

20
Q

examples of egg effector genes

A

yolk proteins, albumin proteins

21
Q

examples of sperm specific genes

A

flagellar proteins, intercellular signaling ligands/receptors

22
Q

what does the combo of transcription factors acquired by the germline depend on?

A

genetics and/or environmental factors, depending on the species

23
Q

describe environmental sex determination

A

environmental cues such as temperature, population density, nutrient availability, day/light cycle determine which gametes are produced; can also induce switching to asexual reproduction

24
Q

describe parthenogenesis

A

laying fertile eggs (budding or fragmentation)

25
Q

what sex determination mechanisms for vertebrates use?

A

wide variety of genetic and environmental factors

26
Q

sex determination in mammals and birds

A

is genetic

27
Q

sperm producer and egg producer in mammals

A

XY; XX

28
Q

sperm producer and egg producer in birds

A

ZZ; ZW

29
Q

in mammals, what T.F. controls sex determination

A

SRY gene on the Y chromosome

30
Q

in birds, what T.F. determines sex

A

DMRT-1 on the Z chromosome

31
Q

role of SRY

A

activates tissue specific effector genes for sperm production and inhibits those for egg production

32
Q

example of a true, completely dominant allele

A

SRY, “sperm production” is inherited according to simple Mendelian traits

33
Q

genes that happen to be on the X chromosome are called?

A

sex or X-linked genes

34
Q

consequence of the Y chromosome is missing lots of genes

A

disease-causing, recessive X-linked alleles ac dominant in gametic males