Biology Lab Report

Biology Lab Report

Lab No. 18: Biochemical Genetics: Smooth Peas Wrinkled Peas

Data Presentation:

The diagram of cotyledon for smooth and wrinkled pea is attached to

the next page.

The table of starch presents is below:

Type of Pea

Starch Present? (Color change)

Smooth

Yes (Dark blue)

Wrinkled

No (No change)

Conclusion

Smooth pea is dominant than wrinkled one, hence we can say the letter

of allele which controls this characteristics is S. ‘SS’ and ‘Ss’ for

smooth, and ‘ss’ for wrinkled.

In the first experiment, we observed the cotyledon of both smooth and

wrinkled pea that contains starch or not using iodine solution. Both

smooth and wrinkled pea changed its color to dark-blue, and it means

that they both contain starch. However, the shape was slightly

different from each other; the smooth one had a brighter color and has

a regular round shape. However, the wrinkled one was much darker and

does not have a regular shape. This result might be caused by some

mistakes, which were the amount of iodine solution and the thickness

of cotyledon.

We get very clear result in the second experiment. The section of

smooth pea changed to dark-blue color when we added iodine solution

and left it for 20 minutes, while the wrinkled pea did not change at

all. In this experiment, we can say that the smooth pea has a

phosphorylase, the enzyme that turns glucose into starch, but the

wrinkled pea does not have a phosphorylase.

Smooth pea has a genotype either ‘SS’ or ‘Ss’ and has an enzyme called

phosphorylase. However, the wrinkled pea that the genotype is ‘ss’,

does not have phosphorylase. Hence we can think that the gene that

causes the absence of phosphorylase is in the recessive gene ‘ss’. If

the recessive gene ‘ss’ causes the absence of phosphorylase, ‘Ss’ gene

smooth pea should contain less amount of phosphorylase than ‘SS’ gene

smooth pea. However this might not be true if more than one gene