How We Get Our Skin Color PDF

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Interactive Video How We Get Our Skin Color

Student Worksheet

Before you begin, think about your skin. It covers your entire body! What questions do you have about skin and skin color?

Watch the entire animation once through. Go through it once more, stopping at each stop point, indicated by the white bars. First Stop Point: What Is Skin? Click on “learn more” to access interactive art and a short video about the functions of the different skin layers and how vitamin D is synthesized. 1. Describe the primary function(s) for each of the skin layers named below. Epidermis

• Protect body from elements (winds & UV rays) • Keeps bacteria & viruses out and water in • Let’s oxygen in to produce vitamin D

Dermis • Contain blood vessels, hair follicles, etc • Provides the epidermis with oxygen and nutrients

Hypodermis • Contains fats • Insulates the body • Protective padding for body and stores energy

2. Why is vitamin D important to our health? It prevents our body from getting rickets and osteomalacia. It strengthens our bones and helps our immune system.

3. What is the connection between skin, sunlight, and vitamin D? UV rays comes from the sun, starting the process that makes inactive vitamin D and makes it active as it circulates in the blood.

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Published November 2015 Page 1 of 6

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Interactive Video How We Get Our Skin Color

Student Worksheet

a treatment you would recommend to the child’s parents and why you recommend that course of action. I would recommend vitamin B pill, and lots of sunlight.

Second Stop Point: What Are Skin Cells? Go to the second stop point in the animation to learn about the types of skin cells in the epidermis and why humans lost their hair.

Makes 1% of the epidermis. Produces melanin.

Delivers melanosomes to keratinocytes

7 million years ago.

b. What advantage did sweat glands and less body hair provide in our ancestors’ environment? Sweat glands allow us to get rid of toxins and also cool down when our body temperature gets to high. Less body hair allowed us to receive more vitamin B so that we would get any deficiencies.

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Interactive Video How We Get Our Skin Color

Student Worksheet

Third Stop Point: What Is Melanin? Move to the third stop point to learn about how melanin is made inside melanocytes and one of the genes that controls skin color.

The two primary types of melanin are pheomelanin and eumelanin, their difference is that pheomelanin is reddish-yellow colour, while eumelanin is a brown and black.

13. Explain how the amount of eumelanin and number of melanosomes differ between a person with lighter color skin and a person with darker color skin. The difference is that if you have lighter coloured skin you have less eumelanin but if you have a darker skin colour then you have more eumelanin.

14. Which type of melanin is produced by the version of the MC1R gene (i.e., the MC1R allele) most prevalent among people of African ancestry? MC1R is produced by eumelanin.

15. What can be inferred from the fact that there is little diversity in the form of MC1R gene found among individuals from equatorial Africa? There is little diversity because all the individuals from the equator need to have that MC1R so there was little reason for the body to change it.

Fourth Stop Point: How Does Melanin Protect Cells? Visit the fourth stop point to learn about how melanin protects DNA from UV damage and how mutations in DNA lead to cancer. 16. a. Name two molecules in the body that UV radiation can damage. DNA and folate.

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Interactive Video How We Get Our Skin Color!

Student Worksheet !

! b. How does melanin protect these molecules from UV damage? It creates a melanin “umbrella” over the nucleus which protect the DNA and the folate in he blood.

17. What are pyrimidine dimers, what causes them, and why are they dangerous? UVB radiation pyrimidique dimes, they are dangerous they form two adjacent pyrimidine bases become linked in an abnormal structure that causes a kink.

18. How can pyrimidine dimers lead to cancer? The DNA will try to repair its self and as it does it may mutate and cause irregular cell reproduction.

Fifth Stop Point: How Does Sunlight Cause Tanning? Go to the fifth stop point to learn about the different types of UV radiation and how they affect melanin production. 5

19. Fill in the blanks. UV radiation has __________________________ wavelengths and 5 _______________________ energy than visible light and infrared radiation.

20. What are the positive and negative effects of UVB exposure? It produces vitamin D but also causes mutation in DNA and destroys folate.

21. Explain how the relationship between skin color and UV radiation provides evidence that this trait evolved by natural selection. The higher the UV radiation the darker the skin tone is because you receive more of it.

22. What is the selective pressure for darker skin color? For lighter skin color? The selective pressure for darker skin colour is eumelanin and lighter skin colour is pheomelanin

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Interactive Video How We Get Our Skin Color!

Student Worksheet !

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23. Explain the difference between constitutive and facultative skin color.

24. What causes skin to tan? What causes skin to sunburn? Skin tans because it is responding to the UV radiation and is creating protection. Sun burn happens when you receive to much UV radiation before you can create protection.

25. Your friend, who tans easily, argues that it’s great to get a tan because darker skin pigmentation offers lots more protection from damaging UV radiation, so he’s keeping himself safe. Would you agree? Explain. No, because if he tans to much the he will not be able to protect himself because he got to much UV radiation and may get skin cancer.

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Interactive Video How We Get Our Skin Color!

Student Worksheet !

! 26. Use arrows to connect the concept bubbles below, making a concept map. Be sure to label your arrows with verbs or linking words, as shown in the example.

Skin Skin Color

is made up of

3 layers Keratinocytes Melanosomes Epidermis

Melanocytes Melanin 7-dehydrocholesterol DNA Vitamin D UV radiation

Return to the questions you listed at the beginning. Using the information you learned in this activity, answer any questions you can in the space below. Because nether of the melanins have a blue property to them

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