Genetic Linkage & mapping in eukaryotes 4 Flashcards

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1
Q

Synteny

A

Two or more genes are located on the same chromosoome (physically linked)

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2
Q

Genetic linkage

A

Genes that are close to each other tend to transmitt together as linked genes

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3
Q

Genes on the same chromosome that are close to each other are ________________

A

Physically linked (Can’t independently assort)

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4
Q

When genes on the same chromosome are _____________ then independent assortment can happen

A

Far apart

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5
Q

In an 9:3:3:1 ratio how many offsprings will have the parental phenotype?

A

10 ( 9 will have the dominant trait & 1 will have the recessive trait)

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6
Q

In ______________ the domiant trait will show the most in a data and then the recessive trait will be the second most to show in a data

A

Linked genes

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7
Q

In _______________ genes the dominant trait will show the most in a dat & the recessive trait will show the least (9 domiant, 1 recessive) (9:3:3:1)

A

Independent assorted

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8
Q

If linked genes are ___________ independent assortment will occur but the rate of independent assortment will depend on the distance apart

A

Far Apart

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9
Q

Independent assortment of linked genes leads to crossing over which results in ________________

A

Recombinant geneotypes & offsprings

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10
Q

Crossing over occurs in ___________ where the homologous sister chromatids pairs up & each one switch a fragment with each other

A

Prophase 1 in meiosis 1

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11
Q

Recombinants

A

Combinations of genotypes that are different from the parents

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12
Q

Why doesn’t crossing over occur within sister chromatids?

A

Because sister chromatids are identical to each other therefore won’t have any genetic diversity

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13
Q

The likelihood of crossing over between two genes depends on the ________________

A

Distance between them

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14
Q

If two genes are __________ the crossing over will occur

A

Far apart

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15
Q

If two genes are _________ then crossing over wont happen

A

Close together

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16
Q

A _____________ can be used to determin if two genes are linked or not

A

Chi square test

17
Q

If the chi sqaure value is ______ then can agree that the genes are not linked & they are indenpendly assortted

A

Low

18
Q

What is the null hypothesis when determine if genes are linked or not?

A

That they are not linked & assort independly

19
Q

If the chi square test is ______ then have to reject the null hypothesis & agree that the genes are linked

A

High

20
Q

Genetic mapping

A

Determines the linear order & distance of seperation among genes that are linked to each other on the same chromosome

21
Q

The goal of a test cross is what?

A

To determine if recombination has occured

22
Q

What is the equation for map distance (or % recombination)?

A

Map distance (% recombination) = # of recombinants/ total offspring x 100

23
Q

m.u. is the same as ___________

A

% recombinant

24
Q

If no crossing over happens then the genotype would be the same as ________________

A

The parents

25
Q

How can you tell genes are linked when looking at a data?

A

When the two parental phenotypes are the 1st highest & second highest

26
Q

How can you which numbers in a data represents a single cross over?

A

The numbers that are 3rd & 4th highest (common ones after the two parental phenotypes)

27
Q

How can you tell which number represents a double crossover in a data?

A

The lowest number represents a double crossover

28
Q

When a single crossover occurs what happens/

A

The two genes on the end changes but not the middle gene

29
Q

In a double cross over what happens?

A

Only the middle gene changes

30
Q

If it says what is the frequency (%) of a certain parental gene what do you have to do?

A

Fidn the total frequency(%) of parental genes & divde it by to for the certain parental gene

31
Q

When you find the total % recombination what should you do?

A

Divide that number by 2 so you have the % recombination for each recombinant

32
Q

How do you find the % recombination in a double cross?

A

Multiple the two single % recombination together

33
Q

How would find the total % or amount of offsprings that will have the parental genotype (no crossover)?

A

100- all the single cross over % - double crossover %

34
Q

Interference (I) represents what?

A

The amount or % of double crossover that didnt occur

35
Q

What is the formula for interfernce?

A

I = 1- C

(C- coeffiecient of coincidence which tell the % or amount of double crossover that did occur)

36
Q

What is the formula to calculate C in interfernce?

A

Observed # of double crossover/ expected # of double crossover

37
Q

Interference is used for what type of crossing over?

A

Double crossover

38
Q

When you see the words recombinant genes what does that tell you?

A

That crossing over has to occur (usually single crossover if middle gene stays the same)