REGULATION OF THE CELL CYCLE Flashcards
Name, locate and describe the function of the three checkpoints which occur at various points of the cell cycle
The three checkpoints in the cell cycle are:
- G1 checkpoint: Located at the end of G1 phase, it checks for DNA damage and ensures the cell is ready for DNA synthesis.
- G2 checkpoint: Located at the end of G2 phase, it ensures DNA replication is complete and checks for DNA damage before mitosis.
- M checkpoint: Occurs during metaphase of mitosis, ensuring all chromosomes are properly attached to the spindle fibers before cell division proceeds.
Describe the function of the spindle
The spindle is a structure made of microtubules that helps separate chromosomes during cell division by attaching to centromeres and pulling sister chromatids to opposite poles of the cell.
Differentiate between sister chromatids and chromosomes
Sister chromatids are identical copies of a chromosome, joined together by a centromere, formed during DNA replication, while chromosomes are the structures that carry genetic information, made up of DNA, and are visible during cell division.
Identify actively dividing cells in human tissues
Actively dividing cells in human tissues are typically found in areas such as the skin, bone marrow, digestive lining, and hair follicles, where rapid cell turnover is necessary.
Define apoptosis and describe how it occurs
Apoptosis is programmed cell death, a controlled process where a cell self-destructs in response to signals such as DNA damage or stress, involving steps like cell shrinkage, DNA fragmentation, and the formation of apoptotic bodies for clearance.
Explain why apoptosis is required and naturally occurs
Apoptosis is required to remove damaged, infected, or unnecessary cells, maintaining healthy tissue function and preventing cancer. It naturally occurs to ensure proper development, immune system function, and tissue homeostasis.
Explain how cancers can occur
Cancers occur when mutations in a cell’s DNA lead to uncontrolled cell division, bypassing normal regulatory mechanisms, allowing cells to grow and spread uncontrollably.
Identify the four steps that occur in apoptosis
The four steps of apoptosis are: 1) Activation of death signals, 2) Cell shrinkage and membrane blebbing, 3) DNA fragmentation, and 4) Formation of apoptotic bodies, which are then cleared by phagocytes.
Name the two mechanisms by which apoptosis can be achieved and differentiate between them
Apoptosis can be achieved through the intrinsic pathway, where internal signals like DNA damage trigger cell death, and the extrinsic pathway, where external signals from death receptors on the cell surface initiate the process.
Differentiate between normal cells and cancer cells
Normal cells grow and divide in a controlled manner, while cancer cells grow uncontrollably, ignore signals to stop dividing, and can invade other tissues.
Differentiate between malignant and benign
Malignant tumors are cancerous, invasive, and can spread to other parts of the body, while benign tumors are non-cancerous, grow locally, and do not spread.
Describe metastasis
Metastasis is the process by which cancer cells spread from their original site to other parts of the body through the bloodstream or lymphatic system.
