Educational worksheet on skin structure and function, including a crossword and sequence of events for forming new skin cells.

Let’s go step by step to solve the “Sequence of Events: Formation of New Skin Cells” problem.

We are given 5 events labeled A through E, and we need to put them in the correct order — from first to last — as skin cells form and move upward through the layers of the epidermis.

Here are the events again:

A. Flattened, dead cells called keratinocytes arrive at the stratum corneum.
B. Cells stop dividing and produce keratin, which replaces the cytoplasm and nucleus of the cell.
C. Stem cells in the stratum basale undergo mitosis.
D. The cells flatten and die.
E. As new cells are produced, they push older cells upward.

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Step 1: Where does it all start?

Skin cell formation begins in the deepest layer of the epidermis — the stratum basale. That’s where stem cells live and divide. So event C must be first:

→ C. Stem cells in the stratum basale undergo mitosis. (This is step #1)

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Step 2: What happens after new cells are made?

When new cells are created, they don’t just sit there — they push the older cells above them upward. So next comes:

→ E. As new cells are produced, they push older cells upward. (This is step #2)

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Step 3: What happens to those pushed-up cells?

As they move up, they stop dividing and start making keratin — a tough protein that fills the cell and eventually replaces its insides (cytoplasm and nucleus). So:

→ B. Cells stop dividing and produce keratin, which replaces the cytoplasm and nucleus of the cell. (This is step #3)

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Step 4: What happens after they fill with keratin?

They begin to flatten out and die — because they’ve lost their nucleus and can no longer function as living cells.

→ D. The cells flatten and die. (This is step #4)

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Step 5: Where do they end up?

Finally, these dead, flattened cells reach the very top layer — the stratum corneum — where they act as a protective barrier before falling off.

→ A. Flattened, dead cells called keratinocytes arrive at the stratum corneum. (This is step #5)

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So the correct sequence is:

1. C
2. E
3. B
4. D
5. A

Final Answer:
C, E, B, D, A