Name ___________________________

Cell Cycle- Science Skills

The cell cycle is a repeating cycle of cellular growth and division- it occurs during the entire life of an organism, from birth until death. The cell cycle is typically a four-phase process followed by cytokinesis. An individual cell spends about 90% of its time in the first three phases of the cycle, which collectively is called interphase. A cell will enter the last phase of the cell cycle only if it is about to divide.

The phases of mitosis are as follows:

First growth phase (G1): During this phase the cell grows rapidly and carries on routine functions. For most organisms, this phase occupies the major portion of a cell’s life.

Synthesis phase (S): A cell’s DNA is replicated (copied) during this phase. The DNA transforms from chromatin (one copy; shapeless) to sister chromatids (two copies; “X” shaped).

Second growth phase (G2): In the G2 phase, preparations are made for the nucleus to divide (mitosis). Cell organelles, such as mitochondria, replicate to prepare for two cells. Hollow protein fibers called microtubules are assembled. Microtubules are used to help move chromosomes during cell division.

Mitosis + Cytokinesis: The process of one nucleus dividing into two nuclei is known as mitosis. Each nucleus ends up with an equal amount of chromosomes. The process of the cytoplasm dividing is known as cytokinesis.

1. How are mitosis and cytokinesis alike? How are they different? _______________________________________________________________________________________________________________________________________________________________________________________.

2. A cell under a microscope appears to be in the fourth phase of the cell cycle. What does this indicate about the cell? _____________________________

____________________________________________________________.

Match each statement with the phase in the cell cycle it describes. Write the letter of the correct phase in the space. You will use the terms more than once for some choices.

3. _____ nucleus divides.

4. _____most of the cell’s life is during

this phase

5. _____cytoplasm divides

6. _____ the mitochondria replicate

7. _____cell grows rapidly

8. ____two identical nuclei are created

9. _____ DNA is copied

10. _____microtubules are assembled

11. _____sister chromatids are formed

12. _____cell carries out routine functions

13. _____ microtubules move chromosomes

14. Choose the phrase that best completes the analogy:

G2 phase is to mitochondria as S phase is to ________________

a. Choromatids

b. Centromere

c. Microtubules

d. DNA

1. Match the parts of the cell cycle with the following terms by writing each letter next to its corresponding number.

PHASES OF THE CELL CYCLE

a. Prophase e. Synthesis phase

b. G1 f. G2

c. Telophase g. anaphase

d. Metaphase

Shade the pieces of the cell cycle that are part of interphase YELLOW.

Shade the pieces of the cell cycle that are part of the mitotic phase RED.

Cytokinesis is not reflected on the cell cycle above. Figure out when cytokinesis occurs and draw two small circles to mark when it would take place during the cell cycle.

2. Write the names of each stage of mitosis that is represented below each cell:

___________________ _______________________ ______________________ ________________________

3. Write the 4 phases of mitosis in order:

4. ___________________,

5. ___________________,

6. ___________________,

7. ___________________.