Unit 4 Target 3: Mitosis Quiz

When a cell divides, each daughter cell receives its own copy of the parent cell's DNA. This is an essential process to ensure that each new cell has the necessary genetic information to function properly. This allows for the transmission of genetic material from one generation to the next, and is crucial for the growth and development of organisms. The other options are incorrect because they do not accurately describe what happens during cell division.

The structure labeled B in the figure above are called sister chromatids. Sister chromatids are identical copies of a chromosome that are formed during DNA replication. They are held together by a region called the centromere, which is responsible for ensuring that each daughter cell receives one copy of the chromosome during cell division. The term "spindles" refers to the structures involved in separating sister chromatids during cell division, while "centrioles" are involved in organizing the spindles. However, in the given figure, the structure labeled B specifically represents sister chromatids.

During metaphase, the chromosomes line up along the middle of the dividing cell. This is a crucial step in mitosis, as it ensures that each daughter cell receives an equal number of chromosomes during cell division. The alignment of chromosomes at the cell's equator is facilitated by the spindle fibers, which attach to the centromere of each chromosome and help to position them correctly. Once the chromosomes are properly aligned, they are ready to be separated and pulled apart during anaphase. Therefore, metaphase is the correct phase of mitosis for the chromosomes to line up in the middle of the dividing cell.

The structure labeled A in the figure is the centromere. The centromere is a region on a chromosome where the two sister chromatids are held together. It plays a crucial role in the separation of the sister chromatids during cell division. The centromere contains specialized proteins that help attach the spindle fibers, which are responsible for pulling the sister chromatids apart. Therefore, the correct answer is centromere.

During the first phase of mitosis, called prophase, the chromatin condenses into visible chromosomes. The nuclear envelope breaks down, and the spindle fibers begin to form. The centrosomes move to opposite poles of the cell, and the microtubules extend from them to form the mitotic spindle. The chromosomes then become attached to the spindle fibers at their centromeres. Therefore, prophase is the correct answer for the first phase of mitosis.

In the given figure, B represents telophase. This can be identified by the presence of two distinct nuclei forming at opposite ends of the cell. In telophase, the nuclear envelope reforms around each set of chromosomes, and the spindle fibers disassemble. This marks the final stage of mitosis, before the cell undergoes cytokinesis and divides into two daughter cells.

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The correct answer is "prophase, metaphase, anaphase, telophase." This is the proper sequence of the phases of mitosis. Prophase is the first phase, during which the chromosomes condense and the nuclear envelope breaks down. Metaphase is the second phase, where the chromosomes align at the center of the cell. Anaphase is the third phase, where the sister chromatids separate and move towards opposite poles of the cell. Telophase is the final phase, where the nuclear envelope reforms and the chromosomes decondense.

Picture C represents anaphase because it shows the separation of sister chromatids, which is a key characteristic of anaphase. In anaphase, the sister chromatids are pulled apart by spindle fibers towards opposite ends of the cell, preparing for cell division. Picture C clearly shows this separation, indicating that it represents anaphase.

During mitosis, the spindle plays a crucial role in separating the chromosomes. The spindle is a structure made up of microtubules that attach to the chromosomes and pull them apart. It ensures that each daughter cell receives the correct number of chromosomes during cell division. The spindle fibers attach to the centromeres of the chromosomes and exert force to move them towards opposite poles of the cell. This process ensures the equal distribution of genetic material and the formation of two genetically identical daughter cells.

Picture A represents metaphase because it shows the chromosomes aligned along the equator of the cell. In metaphase, the chromosomes are fully condensed and attached to the spindle fibers, preparing for their separation during anaphase. Picture B shows chromosomes scattered and not aligned, which is not characteristic of metaphase. Picture C shows chromosomes starting to separate, indicating anaphase. Picture D shows chromosomes already separated, indicating telophase. Therefore, Picture A is the correct representation of metaphase.

During prophase, the chromosomes condense and become visible. They also pair up with their homologous chromosomes and the nuclear envelope starts to break down. In metaphase, the chromosomes line up along the equator of the cell and become attached to the spindle fibers. Therefore, the chromosomes in the given figure are most likely in the prophase and metaphase stages of mitosis.

Mitosis is the correct answer because it is the process by which a cell's nucleus divides to form two identical daughter cells. During mitosis, the chromosomes in the nucleus duplicate and then separate into two sets, which are then evenly distributed to the daughter cells. This process ensures that each daughter cell receives the same genetic material as the parent cell.