Question

Growth factors lead to a. increased cell division. b. the functioning of cyclin proteins. c. progression through the cell cycle. d. All of these are correct.

Short answer

The correct answer is (d) All of these are correct. Growth factors play a vital role in increased cell division, the functioning of cyclin proteins, and progression through the cell cycle.

Step-by-step solution

Option a: Increased cell division

Growth factors are proteins that stimulate cell proliferation. They bind to specific receptors on the cell surface, transmitting signals that trigger cell division. So, option a is correct.

Option b: The functioning of cyclin proteins

Cyclin proteins play a crucial role in controlling cell cycle progression. Growth factors can influence the production and activation of cyclins, which in turn regulate cell cycle events. Therefore, option b is also correct.

Option c: Progression through the cell cycle

The cell cycle is a series of events that occur in a cell, leading to its division and duplication. Growth factors are essential for initiating and regulating these events, ensuring proper progression through the cell cycle. Thus, option c is correct as well.

Option d: All of these are correct

As we have discussed and identified that growth factors play a vital role in all three processes mentioned in options a, b, and c, it is clear that option d, which states that all the options are correct, is the right answer to this exercise.

Key concepts

Cell Division

Cell division is a fundamental process where a single cell divides into two daughter cells. This process is essential for growth, development, and tissue repair in multicellular organisms. It begins with a single cell that replicates its DNA to ensure that each daughter cell receives a complete set of genetic information. This is crucial for maintaining genetic consistency across cells.

There are different types of cell division, such as mitosis and meiosis. While mitosis results in identical cells mainly for growth and repair, meiosis leads to genetic variation, crucial for sexual reproduction. Growth factors are proteins that play a critical role in cell division by instructing cells to divide. They bind to receptors on the cell surface and initiate signalling pathways that promote the transition from one cell cycle phase to another.

In summary, cell division is a meticulously regulated process that ensures the maintenance and reproduction of all living organisms.

Cyclin Proteins

Cyclin proteins are key regulators of the cell cycle. They function hand-in-hand with enzymes called cyclin-dependent kinases (CDKs) to control the transition between the different phases of the cell cycle. Cyclins bind to CDKs, activating them, which regulates key transitions like the progression from the G1 phase to the S phase, where DNA replication occurs.

The levels of cyclin proteins fluctuate throughout the cell cycle, coordinating with the timing of various cell cycle events. Each cyclin interacts with specific CDK enzymes to phosphorylate target proteins, leading to the next phase's necessary changes.

Growth factors influence the production of cyclin proteins, thereby ensuring that cells proceed through the cell cycle stages efficiently. Understanding cyclins is crucial because their dysregulation can lead to uncontrolled cell division, often associated with cancer development.

Cell Cycle Progression

The cell cycle is a series of stages that a cell undergoes, leading to its successful division. This cycle consists of four main phases: G1, S, G2, and M phase. Each phase has distinct checkpoints that ensure the readiness of the cell to proceed to the next stage.

- **G1 Phase**: The cell grows and prepares for DNA replication. - **S Phase**: DNA replication occurs, ensuring each new cell will have identical genetic material. - **G2 Phase**: The cell continues to grow and prepares for mitosis. - **M Phase**: Mitosis occurs, culminating in the division of the cell into two daughter cells.
Growth factors are integral to cell cycle progression as they help activate cyclin proteins and enzymes necessary for transitioning between these phases. Without them, cells would not pass the necessary checkpoints, leading to a disruption of normal cellular activities and potentially halting cell division.

In essence, cell cycle progression is a highly controlled process that underpins much of cellular life, playing a pivotal role in growth and maintenance.