Genetics Day 5

Genetics Summer Discussion

Welcome Back!

Today's Topics

• Linkage

• Chi-square Analysis

• Tetrads

Warm-up

Open Ended

What topic were you most confident with during the exam?

Open Ended

What topic were you least confident with during the exam?

Multiple Choice

What does it mean when genes are linked?

• Genes being linked means they are located on different chromosomes.
• Genes being linked means they are not inherited together.
• Genes being linked means they are located close together on the same chromosome.

Linkage and Chi-square tests

We assume independent assortment is occurring.

Null hypothesis

​How much of our deviation can be explained by random chance?

Chi-squared distribution

Produces the test statistic value which is then compared to our chart to produce the probability of the deviation from the null to be explained by random chance.

The Chi-squared test

Math Response

If we expect 9 individuals to present with a phenotype of Yellow Round, and we actually produce 10 individuals who are Yellow Round, what is the Chi-Squared value?

Type answer here

Correct Answer: 0.11

Deg^°

Rad

Hotspot

If we have a chi-squared value of 0.11, p-value of 0.05, and a df=1, what is our critical value?

Explanation Slide...

- If the calculated chi squared value is greater than the critical value, reject the null hypothesis.- If the calculated chi squared value is less than or equal to the critical value, fail to reject the null hypothesis.

Multiple Choice

Do we reject the null hypothesis that independent assortment is occurring?

• No, we fail to reject the null hypothesis. We can say that independent assortment is occurring.

• Yes, we reject the null hypothesis. Independent assortment is not occurring.

Math Response

If we expect 9 individuals to present with a phenotype of Yellow Round, and we actually produce 30 individuals who are Yellow Round, what is the Chi-Squared value?

Type answer here

Correct Answer: 49

Deg^°

Rad

Hotspot

If we have a chi-squared value of 49, p-value of 0.05, and a df=1, what is our critical value?

Multiple Choice

Do we reject the null hypothesis that independent assortment is occurring?

• No, we fail to reject the null hypothesis. We can say that independent assortment is occurring.

• Yes, we reject the null hypothesis. Independent assortment is not occurring.

Explanation Slide...

- If the calculated chi squared value is greater than the critical value, reject the null hypothesis.

- If the calculated chi squared value is less than or equal to the critical value, fail to reject the null hypothesis.

Multiple Choice

In guinea pigs, white coat (w) is recessive to black coat (W) and wavy hair (v) is
recessive to straight hair (V).

We preform the following cross:

wwvv x WwVv

If we retrieve 80 pups, how many of each phenotype are we expecting to see?

• • Black, straight: 20

  • Black, wavy: 20

  • White, straight: 20

  • White, wavy: 20

• • Black, straight: 25

  • Black, wavy: 18

  • White, straight: 22

  • White, wavy: 18

• • Black, straight: 20

  • Black, wavy: 10

  • White, straight: 10

  • White, wavy: 40

• • Black, straight: 15

  • Black, wavy: 25

  • White, straight: 25

  • White, wavy: 18

Math Response

We are given the data of the pups and we retrieve the following:

Black, straight ---- 30
Black, wavy ------- 10
White, straight ---10
White, wavy-------30

What is the chi-squared value?

Type answer here

Correct Answer: 20

Deg^°

Rad

Hotspot

If we have a chi-squared value of 20, p-value of 0.05, and a df=1, what is our critical value?

Multiple Choice

Do we reject the null hypothesis that independent assortment is occurring?

• No, we fail to reject the null hypothesis. We can say that independent assortment is occurring.

• Yes, we reject the null hypothesis. Independent assortment is not occurring.

Imagine a field

Imagine a field

The percentage of times recombination occurs between two genes.

Recombination frequency

Open Ended

In a fictional species of dragons: We are researching if tail spikes are linked to the fire-breathing trait.

We know tail spikes(t) are recessive to smooth tails (T) and fire-breathing (F) is dominant to Acid breath (f).

We cross a het smooth-tail, acid-breath (Ttff) individual to a spiked-tail, het fire-breathing (ttFf ) individual.

Produce the Punnett square under the assumption that independent assortment is occuring.

Math Response

If we are incubating 100 eggs, how many of each phenotype are we expecting?

Type answer here

Correct Answer: 25

Deg^°

Rad

Multiple Choice

If we recover the following:

30 Smooth-tail, Acid-Breath

30 Spiked-tail, Fire-breathing

5 Smooth-tail, Fire-breathing

5 Spiked-Tail, Acid Breathing

Are the two genes linked?

• Not sure
• Yes
• No

Categorize

Options (8)

Smooth-tail, Acid-breath

Spiked-Tail, Fire-Breathing

Smooth-tail, Fire-breathing

Spiked-Tail, Acid-breath

Ttff

ttFf

TtFf

ttff

Categorize the phenotypes and genotypes

Parental Type

Recombinant

Parental Genotype

Recombinant Genotype

Math Response

How many recombinants in total are there?

Type answer here

Correct Answer: 10

Deg^°

Rad

Math Response

What is the recombination frequency?

(Hint: Remember to multiply by 100)

Type answer here

Correct Answer: 10

Deg^°

Rad

Cool-Down

Word Cloud

What topics would you most like to cover this week?

All done!

Tomorrow's Topics

• Bacterial Genetics

• Gene-Mapping

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