1 Mitosis Flashcards
A microbiologist discovers a new prokaryotic species that shows unusual genomic features. How might the genome of this prokaryote differ from that of eukaryotes in terms of structure and replication? What implications could these differences have for genetic manipulation in biotechnology?
Prokaryotic genomes typically consist of a single circular chromosome and lack histones, while eukaryotic genomes are organized into multiple linear chromosomes and associated with histones. Prokaryotes replicate their genome using simple mechanisms, whereas eukaryotes have a more complex replication process involving multiple origins of replication and chromatin remodeling. These differences impact genetic manipulation in biotechnology, as eukaryotic systems often require more complex methods to introduce or alter genetic material.
A student confuses the terms “centromere” and “telomere” while studying chromosome structure. How would you clarify these terms, and why is it crucial to understand their differences in the context of genetic inheritance and stability?
The centromere is the central region of a chromosome where the two chromatids are joined and where spindle fibers attach during mitosis. The telomere is the repetitive DNA sequence at the ends of chromosomes that protects them from deterioration. Understanding these terms is crucial because centromeres are essential for chromosome segregation, and telomeres play a role in cellular aging and stability.
During mitosis, a cell’s chromosome fails to separate properly. What are the potential outcomes of such an error for the daughter cells? How could this mistake affect the organism at both the cellular and organismal levels?
If chromosomes fail to separate properly (nondisjunction), the daughter cells may end up with an abnormal number of chromosomes, leading to aneuploidy. This can result in genetic disorders or cancer. In multicellular organisms, such errors can affect development, growth, and overall health, potentially leading to conditions like Down syndrome or cancer.
A researcher is analyzing a set of micrographs from a cell undergoing mitosis. They observe cells with chromosomes aligned in the middle of the cell. Which phase of mitosis are they observing, and what key events are occurring in this phase that are critical for accurate chromosome segregation?
If chromosomes are aligned in the middle of the cell, the researcher is observing metaphase. In metaphase, chromosomes are lined up along the metaphase plate, and spindle fibers attach to their centromeres. This alignment ensures that chromosomes are evenly distributed between the two daughter cells.
A patient is undergoing treatment with a drug that targets the S phase of the cell cycle. How would this drug impact the cell cycle phases, and what specific cellular processes are disrupted by targeting the S phase?
A drug targeting the S phase would interfere with DNA replication. During the S phase, the cell duplicates its DNA, so inhibiting this phase would prevent the cell from completing replication, thereby blocking cell division. This can be useful for treating rapidly dividing cancer cells but may also affect normal cells that are actively dividing.
A genetic mutation leads to the overexpression of a cyclin that regulates the G1 to S phase transition. How might this mutation affect the normal regulation of the cell cycle, and what are the potential consequences for cell division and cancer development?
Overexpression of a cyclin that regulates the G1 to S phase transition can lead to uncontrolled progression through the cell cycle, bypassing normal checkpoints and leading to increased cell proliferation. This loss of regulation is a common feature in cancer, and targeting cyclin-dependent kinases or their regulatory pathways can be a strategy for cancer therapy.
A tumor suppressor gene is found to be mutated in a patient with cancer. How does the loss of function of this gene contribute to uncontrolled cell division, and what therapeutic strategies might target this issue?
The loss of function in a tumor suppressor gene, such as p53, impairs the cell’s ability to respond to DNA damage and control cell cycle checkpoints. This results in unregulated cell division and increased potential for mutations. Therapeutic strategies might include restoring the function of the tumor suppressor gene or targeting downstream pathways affected by its loss.
A patient is diagnosed with a malignant tumor that has spread to distant organs. How would you distinguish this type of tumor from benign and metastatic tumors, and what treatment approaches are typically considered for each?
Benign tumors are non-cancerous and do not spread to other parts of the body. Malignant tumors are cancerous and can invade nearby tissues. Metastatic tumors originate from a malignant tumor and spread to distant organs. Treatment approaches vary: benign tumors may be removed surgically, malignant tumors might be treated with surgery, radiation, and chemotherapy, while metastatic tumors often require more aggressive systemic therapies.
Cancer cells exhibit several differences from normal cells. How do these differences impact the effectiveness of conventional cancer treatments, and what are some strategies being developed to specifically target cancer cells while minimizing damage to normal cells?
Cancer cells often have uncontrolled growth, evasion of apoptosis, and the ability to invade surrounding tissues. These differences affect treatment effectiveness, as conventional therapies may also damage normal, rapidly dividing cells. Strategies like targeted therapies and immunotherapies are being developed to specifically address cancer cells while minimizing harm to normal cells.
Chemotherapeutic drugs that inhibit the cell cycle are known to have severe side effects. How do these side effects arise from the drugs’ mechanisms of action, and what approaches are being investigated to reduce these adverse effects while maintaining therapeutic efficacy?
Chemotherapeutic drugs that inhibit the cell cycle can affect all rapidly dividing cells, not just cancer cells. This includes cells in the hair follicles, digestive tract, and bone marrow, leading to side effects such as hair loss, nausea, and anemia. Research is focused on developing more selective drugs and improving drug delivery systems to reduce these side effects while maintaining effectiveness against cancer cells.
