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Cell and Homeostasis
Name: ___________________
Cell Division
1 - Cell division occurs in unicellular organisms and in multicellular
organisms. However, the results of cell division are different
depending on how many cells an organism has. Unicellular
organisms use cell division to reproduce. In multicellular organisms,
most cell division occurs in order to repair or renew old tissue. This
renewal process is essentially continuous in some cells, such as
those in the skin. In addition, some cell division occurs for the
growth of new tissue in multicellular organisms.
2 - Before cell division begins, however, the genetic information it
carries in its DNA must be copied exactly and completely. If this
duplication of genetic material does not occur, the new cells will not
function, and the new tissue will not survive. This copying process is
called DNA replication.
3 - DNA has a shape called a double helix. Two intertwined strands
are each formed by a chain of linked nucleotides. As the replication
process begins, enzymes unwind the two strands from one another.
Then, other enzymes travel along a molecule in order to “read” the
nucleotides in that strand. The copying process proceeds in two
directions at once, shortening the time it takes for duplication.
4 - Absolute accuracy is necessary for a new cell to function
properly. Fortunately, the body’s DNA has a built-in function that
checks the accuracy of a new copy. If any mistakes are found, the
DNA can erase them and insert correct coding information.
Prompt: Your book states that one of the ways to maintain homeostasis is the
reproduction of cells. Based off your reading from the book and the article Cells
and Homeostasis, write a paragraph analyzing the importance of DNA
replication in relation to cellular division and homeostasis.
1. How is cell division different in unicellular organisms and multicellular organisms?
2. What is the importance of copying the DNA exactly and completely?
3. What is the role of enzymes in DNA replication?
4. How is this process important to homeostasis?
Use the DOK question stems to write your own higher order questions.
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