Reproduction + Mutations Flashcards
What are labile (proliferative) cells?
Labile cells are found in the epithelium of skin, GI tract, and urinary tract, and they undergo the most rapid cell division due to constant shedding of cells.
What are hematopoietic stem cells?
Hematopoietic stem cells in the bone marrow produce platelets and blood cells.
What are stable cells?
Stable cells replicate only when stimulated by strong signals, such as growth factors. Examples include hepatocytes in the liver, epithelial cells in kidney tubules, and alveolar cells.
What are permanent cells?
Permanent cells do not return to the cell cycle, such as neurons, skeletal muscle, and cardiac muscle.
How are chromosomes counted?
Chromosomes are counted by the centromere.
What is the importance of the cell cycle?
The cell cycle is important for repairing damaged cells and tissues, allows a unicellular zygote to grow into a multicellular organism, and is essential for asexual reproduction.
What happens during the G-1 phase of interphase?
During the G-1 phase, the number of organelles increases, DNA is replicated, enzymes and transcription factors are produced, and thymine dimers (causes a stiff kink in DNA so DNA polymerase has difficulty reading it- factor causing skin cancer photo-lesions due to UV light) are repaired by scanning DNA before replication.
What happens during the S phase of interphase?
The S phase is the synthesis phase, where semi-conservative DNA replication occurs, and DNA polymerases are used to replicate DNA, increasing the chromosome number from 2n to 4n.
What happens during the G-2 phase of interphase?
During the G-2 phase, the cell continues to grow by increasing its cytoplasm, tubulin proteins are produced for microtubules, and centrioles replicate.
What happens during prophase of mitosis?
During prophase, chromatin forms a dense network, creating thicker chromosomes with sister chromatids attached by the centromere. The nuclear envelope dissolves as proteins are phosphorylated to enable proteases to break it down, and centrioles form microtubules.
What happens during metaphase of mitosis?
In metaphase, centrioles separate to opposite poles, and spindle fibers join to the centromeres by proteins called kinetochores, aligning chromosomes along the equator of the cell. Each sister chromatid is attached to a spindle fiber from opposite poles.
What happens during anaphase of mitosis?
During anaphase, motor proteins move chromosomes toward opposite poles by pulling them along the microtubules, which shorten.
What happens during telophase of mitosis?
In telophase, actin and myosin proteins create a constriction ring at the cleavage furrow to squeeze daughter nuclei apart, and the nuclear envelope reforms around the chromosome groups in each daughter cell. Chromatin becomes diffuse, and spindle fibers break down.
What is cytokinesis in mitosis?
Cytokinesis evenly distributes the cytoplasm between the daughter cells, forming two genetically identical diploid cells.
How is the movement from one phase of the cell cycle to another regulated?
Movement from one phase to another is regulated by cyclins (regulators), which activate cyclin-dependent kinases. These kinases catalyze the phosphorylation of proteins that activate or inactivate genes by binding to them.
How do growth factors control the cell cycle?
Growth factors bind to receptors, activating an enzyme cascade and transcription factors (kinases), which control gene expression of genes which control transcription and initiate the cell cycle.
What are transcription factors?
Transcription factors stimulate genes to produce other transcription factors, creating a cascade of events that regulate the cell cycle.
How do tumor suppressor genes like P53 function?
Tumor suppressor genes like P53 inhibit cell division when mistakes are detected in DNA, stimulate DNA repair enzymes, and can trigger apoptosis of genetically damaged cells.
What is checked at the G1/S checkpoint?
The G1/S checkpoint checks for damage to DNA and ensures that all chromosomes have been replicated.
What is checked at the G2/M checkpoint?
The G2/M checkpoint performs an additional check for DNA damage.
What is checked at the M checkpoint?
The M checkpoint ensures that chromosomes are correctly attached to the spindle fibers.
What happens when p53 genes are mutated?
Mutated p53 genes lead to uncontrolled cell division, resulting in cancerous cells that form tumors and pass on mutated oncogenes.
What are oncogenes?
Oncogenes are genes that have been mutated, leading to abnormal/uncontrolled cell division. Most mutations in oncogenes result in early cell death or are destroyed by the immune system.
What is the difference between benign and malignant tumors?
Benign tumors do not cause cancer and can’t spread throughout the body, while malignant tumors can damage normal functions and spread via blood or lymphatic systems, forming secondary growths (metastasis).
