Bio182-01 - lab worksheet template PDF

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Hardy-Weinberg Equilibrium and Natural Selection Data Directions: Use the information obtained in the Hardy-Weinberg equilibrium experiment to complete the chart and calculations below. This information should be included in the data section of the formal lab report. Table 1

Calculating the Hardy-Weinberg Equation and Allele Frequency Frequency (decimal) Bead Color

Genotype

Blue

BB

Purpl e White

Bb

Number of Beads

Preexperiment

Postexperiment

bb

The Hardy-Weinberg equation is: p 2 + 2pq + q2 = 1 In this equation, p is the frequency of the B allele and q is the frequency of the b allele Which means that: p2 is the frequency of the homozygous genotype BB 2pq is the frequency of the heterozygous genotype Bb q2 is the frequency of the homozygous genotype bb Verify the Hardy-Weinberg equation for the starting population of beads: +

+

2

(p )

= 2

(2pq)

(q )

(1)

Calculate the Hardy-Weinberg equation for the final population of beads: +

+

(p2)

= (q2)

(2pq) 2

(1)

2

Remember, the sum of p + 2pq + q should be equal to 1 (p2 + 2pq + q2 = 1). Using the Hardy-Weinberg equation to calculate the allele frequencies, p and q p = frequency of BB genotypes + ½ frequency of Bb genotypes q = frequency of bb genotypes + ½ frequency of Bb genotypes For the starting population: p=

+

For the final population: =

p=

+

=

1

Name:

Hardy-Weinberg Equilibrium and Natural Selection Data q=

+

=

q=

+

=

Remember, the sum of p + q should be 1 (p + q = 1).

2

Directions: Use the results from the Hardy-Weinberg experiment to complete the chart and calculations below. This information should be included in the data section of the formal lab report. Table 2

Random Mating Results for Hardy-Weinberg Experiment Column

2

3

4

5

6

7

8

Mating Type (colors)

Times Draw n

Numbe r Offsprin

Total Offsprin g (col 2

BB Ratio (*)

Bb Rati o (*)

bb Ratio (*)

#BB (col 4 x 5)

———

———

———

———

———

———

BB x BB (blue x blue)

4

BB x Bb (blue x purple)

4

BB x bb (blue

4

Bb x Bb (purple

4

Bb x bb (purple

4

bb x bb (white

4

Total

25

4

Relative Frequenc y

———

———

———

9 #Bb (col 4 x 6)

10 #bb (col 4 x 7)

*Complete the Punnett squares to determine the values for columns 5-7 in Table 2. Use either a fraction or decimal to represent the value of the ratio. Directions: Use the results from the PTC Tasting experiment to complete the table and calculations below. This information should be included in the data section of the formal lab report. Table 3 PTC Tasting Observations

PTC tasting observations Tasters Non-tasters Total

# Students

Fraction of non-tasters in the class (decimal form) number of non-tasters ÷ total number of students = ___________ = tt (homozygous recessive) = q2 t = square root of q2 = q = ___________ T (dominant) = 1 – q = p = _____________

The Hardy-Weinberg equation is: p2 + 2pq + q2 = 1 In this equation, p is the frequency of the T allele and q is the frequency of the t allele Which means that: p2 is the frequency of the homozygous genotype TT 2pq is the frequency of the heterozygous genotype Tt q2 is the frequency of the homozygous genotype tt Verify the Hardy-Weinberg equation for the PTC tasting results: + (p2)

+

= (q2)

(2pq)

(1)

Directions: Use the results from the Natural Selection Experiment to complete the chart and calculations below. This information should be included in the data section of the formal lab report. Table 4

Natural Selection Experiment # Rice Grains Start Black

Red

Start After Round 1 After Round 2 After Round 3 After Round 4 After Round 5

50

50

# Rice Grains Removed Black

Red

# Rice Grains Remainin Black

Red

% Rice Grains Remaining (sum of columns Black

Red

50

50

** To calculate the value for the percent of grains remaining, take the number for each color of rice grains remaining and divide by the total number of rice grains remaining (sum of columns 6 and 7 for that round).

Directions: Fill out the Punnett squares below using a text box or print document and complete by hand.

Directions: Below are topics that should be addressed in the analysis section of the formal lab report in paragraph form. Do not simply list as a question and then answer. Instead, these questions are intended to guide a well-thought out analysis. Be sure to record any resources used to answer these questions in the reference section of the report. Hardy-Weinberg Equilibrium

1. Do these genotype frequencies match the genotype frequencies at the beginning of the experiment? (Refer to the values in Table 2, Row 8, Columns 8-10)

2. Did the allele frequencies, p and q, change or did they remain the same? Is this population evolving or is it still in Hardy-Weinberg equilibrium based on the information obtained? 3. If the data indicates that the population is no longer in Hardy-Weinberg equilibrium, suggest how the procedure could be changed to decrease the influence of chance. 4. Why was it important to return the beads to the population each time? 5. Why were so many beads used?

PTC Tasting (Hardy-Weinberg Equilibrium) Experiment 1. If the class PTC genotype frequency is different from the frequency of the typical US population, discuss at least two factors which could explain why this difference exists. Natural Selection Experiment 1. Explain what the phrase “survival of the fittest” means based on the data.

2. Did the percentage of rice grains remaining stay equal over successive generations? If so, why did it stay the same? If not, what does this suggest about how populations change? 3. What are some weaknesses of this experimental design, and how could this experiment be improved?

References:...