Study "MBIO", a flashcard deck on FORKSAI.
What is the primary event that occurs during the S phase of the cell cycle?
During the S phase, DNA replication takes place, resulting in the duplication of the cell's chromosomes. Each chromosome then consists of two identical sister chromatids.
Which stage of mitosis is characterized by chromosomes lining up at the cell's equator?
Metaphase is the stage of mitosis where chromosomes align themselves along the metaphase plate, which is the imaginary equator of the cell.
Define a 'replicated chromosome'.
A replicated chromosome consists of two identical chromatids joined together at a centromere. This structure forms after DNA replication during the S phase of the cell cycle.
What is the 'centromere' in the context of chromosomal structure?
The centromere is the constricted region on a replicated chromosome where the two identical sister chromatids are attached. It plays a crucial role in chromosome segregation during cell division.
Which of the following describes the 'Anaphase' stage of mitosis? A. Chromosomes condense and the nuclear membrane breaks down. B. Chromosomes line up in the center. C. Sister chromatids are pulled apart. D. Nuclear membranes reform around chromosomes.
C. Sister chromatids are pulled apart. In Anaphase, the sister chromatids separate and move to opposite poles of the cell.
What is the main event that occurs during 'Telophase' in mitosis?
During Telophase, nuclear membranes reform around the separated chromosomes at each pole of the cell. This leads to the formation of two distinct nuclei.
How does 'Cytokinesis' differ in plant and animal eukaryotic cells?
Cytokinesis does not occur the same way in all eukaryotic cells. While animal cells form a cleavage furrow to divide the cytoplasm, plant cells form a cell plate that grows outwards to create a new cell wall.
What are 'oncogenes' and what is their role in cell growth?
Oncogenes are genes that stimulate cell growth. When mutated, they can contribute to uncontrolled cell division and the development of cancer.
Distinguish between 'oncogenes' and 'tumor suppressor genes'.
Oncogenes stimulate cell growth, and their overactivity can lead to cancer. In contrast, tumor suppressor genes stop cell division and initiate programmed cell death, acting as brakes on cell growth.
What is 'apoptosis' and how do cancer cells avoid it?
Apoptosis is programmed cell death, a normal process for eliminating damaged or unnecessary cells. Cancer cells avoid apoptosis despite having mutations, allowing them to proliferate unchecked.