Lab Report 1 for general biology 2 PDF

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Ashley Sprouse Biology 182L 01/14/20 Dr. Cousineau

Lab Report 1: Hardy-Weinberg Equilibrium and Natural Selection Introduction This laboratory experiment focuses on the Hardy-Weinberg Equilibrium, PTC tasting ability and natural selection. When looking at a particular population to determine if it is evolving, the Hardy-Weinberg Equilibrium equation will be used. If the allele and genotype frequencies stay the same and have no change, they are in equilibrium. Therefore, this means random mating is most likely occurring within the population and not natural selection. In order to meet equilibrium in a population, five conditions have to be met. There has to be no mutations, no gene flow, no natural selection, random mating has to occur, and the population has to be large. (Bledsoe, 2017). However, if one is not met then a population will experience evolutionary change. Using the Hardy-Weinberg equation allows one to see how many alleles of an organism could be present in a group. P stands for the dominant allele and Q stands for the recessive allele. This equation works by taking the genotypes for that population and taking the sum of the homozygous and heterozygous frequencies, the sum should be equal to 1 or 100%. Taking a part, the equation, it allows students to find P and Q on their own. (Bledsoe, 2017). PTC tasting ability is where a person can either taste the bitter taste the chemical presents or they may be unable to. Looking at the population of the United States only 30% cannot taste the

chemical, while the other 70% can. Natural selection is a type of reproduction where organisms will have a greater chance of survival due to heritable characteristics and traits. This allows the organisms to reproduce and pace on traits to their offspring’s. The first experiment deals with the Hardy-Weinberg equilibrium by taking different colored pony beads and making one color the large population. Then students will observe how random selection works and can overall change allele frequency. The PTC tasting ability experiment allows the students to compare the genotype frequency of the class to the United States. The last experiment is a way to observe how natural selection can ultimately cause adaptive evolution. (Bledsoe, 2017). Hypothesis 1. In dark soil, red rice will stand out more than black rice so the. Umber will decrease each trial due to natural selection. 2. As random mating occurred between the pony beads the frequencies did not change because random selecting allowed the Hardy Weinberg criteria to be met. Objectives The main objectives for this laboratory experiment are to understand the five conditions that need to be met for Hardy-Weinberg equilibrium to happen. Figure out the three mechanisms that are most common with evolutionary change. Understand equations dealing with allele frequencies and the Hardy-Weinberg Equation. Lastly, be able to explain the principles of HardyWeinberg equilibrium and evolution from the lab procedures and results. Materials for Hardy-Weinberg Equilibrium 

Container with lid capable of holding 3-4 liters (L)



2 medicine counting trays



Pony beads in three different colors Procedures

1. Obtain the two medicine counting trays and start counting out 490 blue beads, 420 purple beads, and 90 white beads. The color of each bead will be the possible genotypes, such as BB, Bb, and bb. 2. Looking at the specific traits listed above, blue beads are BB, which is the homozygous dominant, the purple beads are Bb, making it the heteroxenous, and the white beads are bb, which is homozygous recessive. 3. Now perform the calculations from the Hardy-Weinberg equation to find p and q. 4. As the beads are all in separate piles, put each color in the container and mix all around. For 25 times grab two beads from the container and record it into the data table, mix the container and repeat until the data table is filled. 5. Use the Punnett square and complete the genotype frequencies and record in the data table. The next rows in the data table are to be multiplied by the corresponding frequencies. For the last three columns, add each number from the possible genotypes that where produced to the mating columns. 6. Lastly, in order to figure out the frequency for random mating between the beads, perform the calculations for p and q. Materials for PTC Tasting Ability 

PTC tasting paper strips



Plain filter paper cut into strips similar in size to PTC paper Procedures

1. Obtain the plain filter paper and place it on the tongue, observe what it tastes like. 2. Once the taste is there and is understood, grab the PTC tasting paper strip and place it inside the mouth. 3. When the PTC tasting paper strip is in the mouth detect if there is a bitter taste and record the observation of the taste into the according data chart. 4. As the class completes this record all the data into the charts and calculate the genotypic frequency of the number of students who could taste the bitterness and who couldn’t. Material for Natural Selection 

Container with lid capable of holding 1 L



Potting soil



Uncooked wild rice and long-grain rice (dyed with food color)



Petri dishes: two



Forceps Procedures

1. Grab one petri dish and fill it with potting soil, not to the very top just 2/3-3/4 full. Grab 50 uncooked wild rice and place it into the soil and obtain the same with the red longgrain rice. The rice combined should add up to 100 and then mix it all together.

2. Select one person to use the forceps to obtain as much rice as possible during the one minute. However, during this experiment if there is an odd number with one of the rice grains, place another one out to make it even. 3. After the one minute goes off, count how many of each color was picked and record it onto the data sheet. Subtract the number that was removed from the total amount at the beginning. 4. Before the next round starts, make sure the total is brought back up to 100. The ratio from 50:50 will most likely change during this experiment. 5. Repeat this process for the next rounds to fill in the rest of the data table. This experiment will show how predation can be simulated within a population. Data Table 1: Pony Bead Data Calculating the Hardy-Weinberg Equation and Allele Frequency Frequency (decimal) Bead Color

Genotype

Blue

BB

Purpl e

Bb

Whit e

bb

Number of Beads

Preexperiment

Postexperiment

490

.49

.57

420

.42

.36

90

.09

.07

Verify the Hardy-Weinberg equation for the starting population of beads:

49 + .42 + .09 = 1.0 (p^2) + (p^2) + (q^2) = 1 Calculate the Hardy-Weinberg equation for the final population of beads: .57 + .36 + .07 = 1.0 (p^2) + (2pq) + (q^2) = 1 Using the Hardy-Weinberg equation to calculate the allele frequencies, p and q For the starting population:

For the final population:

p=490+210= 700

p=570+180=750

q=90+210=300

q=70+180=250

Table 2: Hardy-Weinberg Equilibrium Experiment (pony beads) Random Mating Results for Hardy-Weinberg Experiment Column 1 Mating Type (colors) BB x BB 8 (blue x blue) BB x Bb 10 (blue x purple) BB x bb (blue

2

3

4

5

6

7

8

9

10

Times Draw n

Numbe r Offsprin g

Total Offsprin g (col 2 x 3)

BB

Bb Rati o (*)

bb Ratio (*)

#BB

#Bb (col 4 x 6)

#bb (col 4 x 7)

32

1

40

Ratio (*)

(col 4 x 5)

0

0

32

0

0

1/2

1/2

0

20

20

0

4

0

1

0

0

4

0

20

¼

½

1/4

5

10

5

4

0

½

1/2

0

2

2

4

4

1 4

Bb x 5 Bb (purple

4

Bb x 1 bb (purple

4

bb x bb (white

0

0

0

0

1

100 Total Relative Frequenc y

0

0

0

57

36

7

57%

36%

7%

4

25

———

4

———

———

———

———

———

———

———

———

Table 3: PTC Testing Observations PTC tasting observations

# Students

Tasters (TT or Tt)

16

Non-tasters (tt)

6

Total

22

Fraction of non-tasters in the class (decimal form): Number of non-tasters ÷ total number of students = (6/22) = 0.272 = q^2 T=square root of q^2 = q = 0.522 T(dominant)= 1-q = p = 0.478 Verify the Hardy-Weinberg equation for the PTC tasting results:

0.228 + 0.499 + 0.272 = 0.999

(p^2) + (2pq) + (q^2) = 1

Table 4: Natural Selection Experiment Data Natural Selection Experiment

Black

# Rice Grains Remaini ng

# Rice Grains Remove d

# Rice Grains Start

Black

Red

Black

Red

Red

Start

After Round 1 After Round 2

After Round 3 After Round 4

50

50

% Rice Grains Remaining (sum of columns Black

Red

50

50

8

14

42

36

54%

46%

53

47

14

6

39

41

49%

51%

49

51

7

13

42

38

52%

48%

52

48

14

10

38

38

50%

50%

After Round 5

50

50

16

12

34

38

47%

53%

Analysis The Hardy-Weinberg Equilibrium experiment showed that the genotype frequencies did not match the genotype frequencies at the beginning of the experiment. P and Q did change at the end of this experiment. The reasons for this is because the Hardy-Weinberg Equilibrium criteria was not met. The main factor was the population of 1000 beads was too small and it was not evolving. A way the procedure could have been done differently is to have the student look at the beads before pulling out two of them. This would increase the chances of having the results the same as the projected ones. The number of beads that were used were to help create an actual realization of the Hardy-Weinberg Equilibrium. The PTC genotype frequency of the class compared to the United States was extremely close to one another. The students who could taste the PTC was 73% and the students who couldn’t was 27%. This shows that it was just 3% off from the genotype frequency of the United States. Two factors for this could be that 22 students only participated, so the group was a lot smaller than the United States. Another factor could be gender, more boys could have been tested than girls. Survival of the fittest in this data shows that the black rice should be able to live longer due to the ability of camouflage. The black rice is able to adapt better than the red rice, due to environment. The percentage of rice went back and forth during this experiment, which could have been due to the type of food the predators eat. Certain predators may like the black rice more over the red rice, which shows why the data went back and forth. A weakness in this

experiment could have been doing the experiment in bright lighting. If it was done in dim lighting, the black rice would have been way harder to see, resulting in the red rice to be taken more. Conclusion This experiment explored how natural selection can affect the Hardy-Weinberg equilibrium. Each experiment had a specific part, the first experiment took a large population and saw how random mating would occur and lead to a change in allele frequency. The hypothesis was supported through this experiment because random mating did occur. The second experiment looked at the genotype frequency of students compared to the population of the United States, when testing for PTC taste. The last experiment showed how natural selection can often lead towards adaptive evolution. However, the hypothesis that was stated was correct for a few rounds but overall there was an equal finding of both colors of rice.

References

Bledsoe, S. (2017). Hardy-Weinberg equilibrium, PTC tasting, and natural selection lab. In Grand Canyon University (Ed.), Laboratory manual for General Biology II (2nd ed.). Retrieved from http://lc.gcumedia.com/bio182l/laboratory-manual-for-general-biologyii/v2.1/#/chapter/1

Grand Canyon University (Ed.). (2017). Laboratory manual for General Biology II (2nd ed.). Retrieved from http://lc.gcumedia.com/bio182l/laboratory-manual-for-generalbiology-ii/v2.1/

Appendix

BB

BB

4/4

1.0

BB

BB

BB

BB

Bb

Bb

Bb

Bb

BB

Bb

4/4

1.0

Bb

Bb

Bb

Bb

bb

bb

bb

bb

bb

Bb

bb

1/2

.5

1/2

.5

bb

1/2

.5

1/2

.5

1/4

.25

1/2

.5

1/4

.25

4/4

1.0...