7.1 Inheritance Flashcards

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1
Q

What are the 5 different types of inheritance?

A

codominant
multiple alleles
sex-linkage
autosomal linkage
epistasis

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2
Q

What is a genotype?

A

the genetic constitition of an organism = the alleles it has for 1 gene

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3
Q

What is a phenotype?

A

the expression of genes and its interaction with the environment

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4
Q

What does homozygous mean?

A

a pair of homologous chromosones carrying the same alleles for a single gene

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5
Q

What does heterozygous mean?

A

a pair of homologous chromosome carrying two different alleles for a single gene

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6
Q

What is codominant inheritance?

A

both alleles are equally dominant and expressed in the phenotype

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7
Q

What does multiple alleles mean?

A

more than 2 alleles for a single gene

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8
Q

What does sex-linkage mean?

A

a gene whose locus is on the X chromosome

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9
Q

What does autosomal linkage mean?

A

genes that are located on the same non-sex chromosome

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10
Q

What is epistasis?

A

when 1 gene modifies or masks the expression of a different gene at a different locus

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11
Q

What is monohybrid inheritance?

A

cross of characteristics determined by 1 gene

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12
Q

What is dihybrid inheritance?

A

cross of characteristics determined by 2 genes

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13
Q

What is chi-squared?

A

statistial comparison between observed and expected results

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14
Q

How can you tell something was by chance due to deviation from the expected (chi-squared)?

A

deviation from what was expected is small

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15
Q

How can you tell something was by bias due to deviation from the expected (chi-squared)?

A

deviation from what was expected is large

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16
Q

What is the chi-squared equation?

A

sum of (O-E)^2 / E
E = expected value
O = observed value

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17
Q

How do you calculate the expected value E?

A

sum of observed x phenotype ratio / sum of ratios

18
Q

How do you calculate the degrees of freedom?

A

number of categories (phenotypes) - 1

19
Q

What can you conclude if the x2 value is less than the crititcal value @ P = 0.05?

A

the difference between observed and expected is NOT significant = due to chance
accept H0

20
Q

What can you conclude if the x2 value is greater than the critical value @ P=0.05?

A

the difference between observed and expected IS significant = not due to chance
reject H0

21
Q

what is a dihybrid cross?

A

a genetic cross where the inheritance of 2 genes is considered at the same time

22
Q

How did Mendel discover dihybrid inheritance?

A

found different characteristics in pea plants:
round or wrinkled
green or yellow
purple or white flower

these characteristics are coded by 2 different genes

23
Q

What does F0 represent?

A

parental phenotypes = homozygous

24
Q

What does F1 represent?

A

first generation after x2 homozygous parents combine = heterozygotes 100%

25
Q

What must you include in a genetic cross?

A

parental phenotype and genotype
possible gametes
offspring genotype and phenotype
phenotype ratio

26
Q

What is the F2 phenotype ratio of monohybrid inheritance?

A

3:1

27
Q

What is the F2 phenotype ratio of co-dominant inheritance?

A

1:2:1

28
Q

What is the F2 phenotype ratio of dihybrid inheritance?

A

9:3:3:1

29
Q

What is the result of crossing over in meiosis?

A

new combinations of alleles in the gametes

30
Q

What is the result of crossing over in meiosis?

A

new combinations of alleles in the gametes

31
Q

What is the F2 phenotype ratio of autosomal linkage?

A

3:1

32
Q

How can you tell if crossing over has occured in autosomal linkage?

A

other phenotypes that were not expected in the 3:1 ratio are produed = recombinant offspring

33
Q

What are recombinant offspring?

A

offspring that have a different combination of characteristics than their parents

34
Q

Why are homozygous dominant and homozygous recessive offspring most common in autosomal linkage?

A

their gametes are not as a result of crossing over

35
Q

What happens when genes become further apart on a chomosome?

A

the genes are less linked = increase chance of crossing over = increased chance of recombinant offspring

36
Q

Are females homogametic or heterogametic?

A

homogametic = XX

37
Q

Where are the sex-linked genes located on the X chromosome?

A

in the non-homologous region = Y chromosomes do not have this because they are shorter

38
Q

Who is more likely to suffere from a sex-linked disorder caused by a recessive allele?

A

males = they only have 1 X chromosome so it is easier to obtain a recessive allele

39
Q

What is evidence from a pedigree diagram that a disorder is recessive?

A

2 non-affected parents produce an affected child

40
Q

What evidence from a pedigree diagram shows a disorder is NOT sex-linked?

A

an affected daughter is produced from a non-affected father = the father does not have the recessive allele on his X chromosome

41
Q

How can you tell from a pedrigree diagram that a disorder IS sex-linked?

A

only males have the disorder