Bio 1: Cell Cycle Quiz

The stages of the cell cycle are G1, S, G2, and M. G1 is the first gap phase where the cell grows and prepares for DNA synthesis. S phase is the synthesis phase where DNA replication occurs. G2 is the second gap phase where the cell continues to grow and prepares for cell division. M phase is the mitotic phase where cell division occurs. Therefore, M is not a stage of interphase, but rather the stage where cell division takes place.

During metaphase, the chromosomes line up in the middle of the cell. This is a characteristic of metaphase because it is the stage of mitosis where the chromosomes, which have already replicated during the previous phase, align themselves along the equatorial plane of the cell. This alignment is crucial for the subsequent separation of sister chromatids during anaphase. The nuclear membrane breaks down during prophase, sister chromatids are pulled to opposite sides of the cell during anaphase, and the cytoplasm splits during cytokinesis, which occurs after mitosis.

During anaphase, the sister chromatids, which are duplicates of each chromosome, separate and are pulled towards opposite poles of the cell. This is facilitated by the spindle fibers attached to the centromeres of the chromosomes. As a result, each pole of the cell receives a complete set of chromosomes. The nuclear membrane has already broken down in the previous stage, known as prometaphase. The lining up of chromosomes in the middle of the cell occurs during metaphase, and the splitting of the cytoplasm happens in the subsequent stage, known as cytokinesis.

The S phase of the cell cycle is the phase where DNA replication occurs. During this phase, the DNA in the cell is duplicated, resulting in two identical copies of the genetic material. This is an essential process for cell division and ensures that each daughter cell receives a complete set of DNA. The other options mentioned, such as cell growth, preparation for mitosis, and nuclear membrane reforms, may occur during different phases of the cell cycle but are not specific characteristics of the S phase.

Cytokinesis is the final stage of cell division, where the cytoplasm of the cell divides into two daughter cells. During this process, the cell membrane pinches inwards, forming a cleavage furrow or cell plate, which eventually separates the cytoplasm into two distinct cells. This characteristic of cytokinesis is essential for the formation of two separate daughter cells with their own cytoplasmic contents, organelles, and genetic material.

The correct answer is metaphase. This is because in metaphase, the chromosomes align themselves in the middle of the cell, forming a metaphase plate. This alignment is clearly depicted in the image on the right, indicating that the stage being illustrated is metaphase.

Telophase is the final stage of mitosis where the nuclear membrane reforms around each set of separated chromosomes. During telophase, the chromosomes reach the opposite poles of the cell, and the nuclear envelope starts to reassemble around them. This marks the completion of cell division and the formation of two daughter cells. The other options mentioned, such as cell growth and normal function, cell growth and preparation for mitosis, and DNA replication, are not characteristics of telophase.

The stage of mitosis illustrated on the right is anaphase. During anaphase, the sister chromatids separate and move towards opposite poles of the cell. This is facilitated by the shortening of microtubules and the pulling force exerted by the spindle fibers. The chromosomes appear to be moving away from each other, indicating the characteristic features of anaphase.

The stage of mitosis illustrated on the right is prophase. Prophase is the first stage of mitosis where the chromatin condenses into chromosomes, the nuclear membrane breaks down, and the spindle fibers begin to form. In the image, we can see the condensed chromosomes, the absence of a nuclear membrane, and the presence of spindle fibers, which are all characteristic of prophase.

The stage of mitosis illustrated on the right is telophase. This can be determined based on the appearance of the chromosomes. In telophase, the chromosomes have reached the opposite poles of the cell and are starting to decondense. Additionally, a new nuclear membrane is forming around each set of chromosomes. This is consistent with the image provided, indicating that telophase is the correct answer.

Synthesis is not part of the M phase. The M phase, also known as mitosis, is the phase in the cell cycle where the cell divides into two daughter cells. It consists of several stages, including prophase, metaphase, anaphase, and telophase. These stages involve the condensation and alignment of chromosomes, their separation, and the formation of two new nuclei. Synthesis, on the other hand, occurs during the S phase, where DNA replication takes place. Therefore, synthesis is not part of the M phase.

G zero refers to the phase of the cell cycle where cells are not actively dividing or preparing to divide. Instead, they are in a resting state, performing their specialized functions without undergoing mitosis. This phase is also known as the quiescent phase or the resting phase. Cells in G zero can remain in this state for a prolonged period or can re-enter the cell cycle when triggered by certain signals or stimuli.

G2 phase is the third phase of the cell cycle, following the S phase where DNA is replicated. During G2 phase, the cell continues to grow and prepares for mitosis, which is the process of cell division. This includes synthesizing proteins and organelles necessary for cell division, as well as checking for any errors or damage in the DNA. The nuclear membrane reforms during the end of G2 phase in preparation for mitosis. Therefore, the characteristic of G2 phase is cell growth and preparation for mitosis.

During prophase, the nuclear membrane breaks down, allowing the chromosomes to be more accessible for further cellular processes. This breakdown is necessary for the proper alignment and separation of chromosomes during cell division. The breakdown of the nuclear membrane marks the beginning of prophase and is a key characteristic of this phase.

Plant cells form a cell plate instead of a cleavage furrow during cell division. This is because plant cells have a rigid cell wall surrounding the cell membrane, which prevents the formation of a cleavage furrow. Instead, a new cell wall is formed in the middle of the dividing cell, creating a cell plate that eventually separates the two new daughter cells. This process allows plant cells to divide and grow while maintaining the structural integrity provided by the cell wall.

During telophase, the cell membrane begins to "pinch" inward, forming a cleavage furrow. This furrow is a groove that forms between the two daughter cells, indicating the beginning of cell division. The cleavage furrow eventually deepens and separates the cytoplasm of the parent cell into two distinct daughter cells. This process is known as cytokinesis and is essential for the completion of cell division. The formation of the cleavage furrow ensures that each daughter cell receives the necessary cellular components and genetic material to function independently.

Cytokinesis is the stage of the cell cycle where the cytoplasm of the cell divides into two daughter cells. In this stage, the cell undergoes physical changes to separate the cytoplasm and organelles, forming two distinct cells. The other options, prophase, telophase, and anaphase, are different stages of mitosis where the nucleus and chromosomes undergo changes, but they do not involve the physical division of the cytoplasm. Therefore, the correct answer is cytokinesis.

The G1 phase of the cell cycle is the first phase of interphase, where the cell grows and carries out its normal functions. During this phase, the cell prepares for DNA replication and subsequent cell division. However, the characteristic that best describes the G1 phase is cell growth and normal function, as it is a period of intense metabolic activity and protein synthesis.

The term "metaphase plate" is used to describe the imaginary plane along which chromosomes line up during metaphase. This is the stage of cell division where the chromosomes align in the middle of the cell before separating into two daughter cells. The metaphase plate is important for ensuring that each daughter cell receives the correct number of chromosomes. The other options, such as cell plate, cleavage furrow, and envelope, are not related to the alignment of chromosomes during metaphase.

Mitosis is a process in which a single cell divides into two identical daughter cells. It involves various stages, including the division of the nucleus, where the genetic material is evenly distributed between the two daughter cells. Therefore, the term "mitosis" specifically refers to the division of the nucleus, not the division of the cell as a whole, the division of the cytoplasm, or the replication of DNA.