Cell Cycle and Cancer
Investigation 2 – PreLab
Oncology specialists perform a wide variety of diagnostic procedures to ascertain the condition of tissues and to detect cancer. Diagnostic procedures include scanning techniques, such as x-ray and magnetic resonance imaging, as well as surgical operations and biopsies. They also devise treatment options which include chemotherapy, radiation therapy, and the surgical removal of cancer.
This Investigation is designed to help you to answer the following Focus Questions:
- How do tissues replenish the cells contained within them?
- What controls the process of cell division?
Note: These questions are located in your SDR at the beginning and end of the Investigation.
As a class, read the Background(s) in the Investigation. Read the Background carefully. When finished, discuss the following concepts as a class:
- Cells within the body are produced from other cells in a process called cell division.
- This process requires that the original (parent) cell copies all of its contents, including DNA and organelles, and splits these materials evenly into two new (daughter) cells.
- In this way, the cell has made an exact copy of itself.
- Too much or too little cell division interferes with normal tissue function.
- The process that controls cell division is called the cell cycle.
- The cell cycle is an ordered set of events that results in cell division – the production of two identical cells from a single parent cell.
- The cell cycle can be broken down into 4 distinct phases:
- 1. G1 or GAP phase
- 2. S or DNA synthesis phase Interphase
- 3. G2 or GAP2 phase
- 4. M or Mitosis phase
- During the G1 phase, the cell produces proteins and grows in size. The G1 phase ends when the cell has reached a certain size.
- Then, the S phase, or DNA synthesis phase, begins. During this phase the cell will make an exact copy of the DNA contained in the cell nucleus through DNA replication. At the end of the S phase, each chromosome inside the nucleus of the cell consists of 2 identical sister chromatids.
- Next, the G2 or GAP 2 phase occurs. During this phase the cell has very little activity.
- Finally, the M phase, or Mitosis phase, occurs. During this phase, the sister chromatids produced in the S phase are separated and cell division (cytokinesis) occurs.
- The M phase or Mitosis phase of the cell cycle is made up of four distinct stages. These stages are:
- 1. Prophase
- 2. Metaphase
- 3. Anaphase
- 4. Telophase.
- When a cell is not in one of these stages it is said to be in interphase.
- Mitosis begins with prophase. In prophase, the chromosomes, which each contain sister chromatids produced in the S phase of the cell cycle, condense in the nucleus of the cell. At this stage, the nuclear membrane dissolves. The cell then enters metaphase.
- During metaphase, the duplicated chromosomes line up on the spindle fibers in the center of the cell.
- The cell then enters anaphase, in which the sister chromatids separate and move down the spindle fibers to the opposite ends of the cell.
- Finally, during telophase, the chromatids have moved to the ends of the spindle fibers. The spindle fibers disappear and new nuclear membranes form around each set of chromosomes. At this point, the cytoplasm splits in half and cell division (cytokinesis) occurs.
- The length of time for a cell to complete one full cell cycle (from one phase of mitosis to the next) varies depending on cell type.
- The length of time of the full cycle varies primarily in the G1 (GAP1) phase. Cells can stay in the G1 phase for up to 1 year.
- Control of the cell cycle occurs through specific proteins which are translated from specific genes in the cells DNA. When the cell makes these proteins they allow the cell to transition into the next phase of the cell cycle. These proteins induce or turn on the cell cycle.
- There are also genes that code for proteins that block the cell from moving into the next phase of the cell cycle. These proteins inhibit or stop the cell cycle.
- It is the balance of these cell cycle inducing and inhibiting proteins that control the cell cycle.
- Different cell types have different amounts of these proteins and therefore different lengths of time that they will stay in each phase of the cell cycle.
LEARN THE LabLearner LINGO
The following list includes Key Terms that are introduced in the Investigation Background(s). They should be used, as appropriate, by teachers and students during everyday classroom discourse.
- cell division
- cell cycle
Note: Definitions of these terms can be found on the Introduction page to the CELL.
Note: Additional words may be bolded within the Background(s). These words are not Key Terms and are strictly emphasized for exposure at this time.
SET FOR SUCCESS
- Complete the Recall section in your SDR.
- How do cells multiply?
- Do cells continue to multiply without any kind of controls?
- Play the video below. Remember to follow along with your SDR and make any notes that you think might be helpful.
- After the video, divide into lab groups to discuss strategy for the lab. For example, you may assign certain group members to perform specific functions during the lab.
Note: The purpose of the video is to allow you to anticipate the laboratory experience you will soon encounter. You should leave this PreLab session with a firm idea of what to expect and how to perform in the lab.
Note: Homework is posted below the video.
You should review the Investigation and video in preparation for the Lab.