Organism Growth and Cell Differentiation

When cells leave the cell cycle, they exit during G₁ phase and then enter G₀ phase, a resting period. Most normal cells leave G₀ phase and reenter the cell cycle at G₁ phase before entering S phase. Cancer cells are different because that cannot enter G₀ phase and are likely to do which of the following?

• Fail to complete S phase

• Mutate during G₁ phase

• Repeat the cell cycle continuously

• Die after completing mitosis

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NGSS.HS-LS1-4

Which phase of mitosis is occurring in the cell indicated by the arrow?

• Prophase

• Metaphase

• Anaphase

• Telophase

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NGSS.HS-LS1-4

Which part of the model represents S phase?

• I

• II

• III

• IV

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NGSS.HS-LS1-4

Cells pass through a G₂ checkpoint before entering mitosis. Ideally, if DNA damage is detected, the cells do not enter mitosis until the damage is repaired. Why is DNA damage repaired before cells enter mitosis?

• So that another round of DNA synthesis does not have to take place

• So that the chromosomes can align at the metaphase plate during mitosis

• So that the cytoplasm can be divided equally between the two daughter cells

• So that healthy daughter cells are produced, allowing the organism to continue to grow.

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NGSS.HS-LS1-4

What do the two arrows represent?

• Arrow 1 represents prophase and Arrow 2 represents interphase.

• Arrow 1 represents mitosis and Arrow 2 represents meiosis.

• Arrow 1 represents interphase and Arrow 2 represents mitosis.

• Arrow 1 represents meiosis and Arrow 2 represents prophase.

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NGSS.HS-LS1-4

Oncogenes are mutated forms of genes. Oncogenes can transform a cell into a tumor cell. Some tumor cells are benign, while others are malignant. How does the presence of an oncogene lead to the formation of a tumor?

• ATP production is inhibited.

• Cell division is unregulated.

• Somatic cell growth is inhibited.

• Antibody activity is unregulated.

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NGSS.HS-LS3-2

What is the role of mRNA in expressing specialized structures?

• Making energy available for cellular activities

• Creating bonds to form biomolecules

• Producing sugars that assist with replication

• Providing information to form proteins

Cell differentiation is critical during embryonic development. The process of cell differentiation results in the production of many types of cells, including germ, somatic, and stem cells. Cell differentiation is most directly regulated by

• ATP

• DNA

• lipids

• sugars

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NGSS.HS-LS1-1

NGSS.HS-LS1-4

Which of these occurs just before the cell enters the G₂ stage of the cell cycle?

• The nuclear membrane disintegrates.

• DNA replicates

• Centrioles form

• The nucleolus divides

Cells typically respond to DNA damage in three ways: by ceasing to grow and divide until the damage is repaired, by permanently ceasing to grow and divide, or by dying. In 2010 a group of scientists reported that a certain kind of immune reaction can cause DNA damage that leads to a fourth response. DNA damage can turn off genes involved in cell-signaling pathways. Turing off these genes can cause less-mature cells to divide too rapidly, often leading to the development of

• tumors

• allergies

• hemophilia

• cardiovascular disease

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NGSS.HS-LS3-2