L13 SAQ - Cell

About 90% of the time.

Skin cells.

Liver cells.

<p>Mature nerve cells and muscle cells.</p> Signup and view all the answers

<p>Typically 12-24 hours.</p> Signup and view all the answers

<p>Chiasmata are the sites where nonsister chromatids exchange genetic material, leading to genetic variation in tetrads.</p> Signup and view all the answers

<p>Tetrads align on the metaphase plate and are attached by their centromeres to spindle fibers from centrioles.</p> Signup and view all the answers

<p>Independent assortment is the random alignment and separation of homologous chromosomes during meiosis, leading to genetic variation.</p> Signup and view all the answers

<p>Spindle guides the homologous chromosomes toward opposite poles, while sister chromatids remain attached and move as a unit toward the same pole.</p> Signup and view all the answers

<p>Each pole now has a haploid set of sister chromatids, cytokinesis occurs, and two daughter cells are formed, each with a haploid set of duplicated chromosomes.</p> Signup and view all the answers

<p>Mitosis is the process of nuclear division in eukaryotic cells that occurs when a parent cell divides to produce two identical daughter cells.</p> Signup and view all the answers

<p>During metaphase, the centrosomes are at opposite poles of the cell, the chromosomes migrate to the metaphase plate, and the centromeres of all chromosomes are aligned on the metaphase plate.</p> Signup and view all the answers

<p>During telophase, non-kinetochore microtubules further elongate the cell, daughter nuclei begin to form at the two poles, nuclear envelope forms around chromosomes, nucleoli reappear, chromatin proteins uncoil, and chromosomes become less distinct.</p> Signup and view all the answers

<p>Cytokinesis is the division of cytoplasm and organelles. It involves the contractile ring of actin and myosin that cleaves the cell in two.</p> Signup and view all the answers

<p>Meiosis is a source of distinction as it is the process that allows for the sharing of some but not all characters of each parent. The rules of this sharing game lie in meiosis.</p> Signup and view all the answers

<p>The three main checkpoints in the cell cycle control system are G1/S checkpoint, G2/M checkpoint, and M checkpoint.</p> Signup and view all the answers

<p>When cancer cells ignore normal signals of the cell cycle, they undergo rapid proliferation.</p> Signup and view all the answers

<p>Cyclins are regulatory molecules that fluctuate in concentration and bond with kinases to serve as checkpoints in the cell cycle. Cyclin-dependent kinases (Cdks) are enzymes that phosphorylate molecules and are inactive until cyclins are present.</p> Signup and view all the answers

<p>Growth factors are external signals that control the passage of cells from the G1 phase into the S phase of the cell cycle. They check for correct size and environment. External agents regulate the progression.</p> Signup and view all the answers

<p>Platelet-derived growth factor (PDGF) is a specific growth factor that is required for fibroblast division in wound healing.</p> Signup and view all the answers

<p>Density-dependent inhibition is a physical factor that inhibits cell division when cells come into contact with each other. It regulates cell division by preventing overcrowding.</p> Signup and view all the answers

<p>The main reasons for cell division in the body are developmental growth, maintenance of tissue and organ functions, repair of damaged tissues, and immune cell proliferation.</p> Signup and view all the answers

<p>The Rb protein plays a key role at the G1 checkpoint by determining cell cycle progression through its phosphorylation status.</p> Signup and view all the answers

<p>Cyclin-CDK complex formation phosphorylates the Rb protein and dissociates it from the pRb-E2F complex, allowing progression to the S phase.</p> Signup and view all the answers

<p>MPF triggers progression to M phase by phosphorylating a number of proteins.</p> Signup and view all the answers

<p>MPF is regulated through the phosphorylation and dephosphorylation of specific sites on the CDC2 subunit and the degradation of cyclin B.</p> Signup and view all the answers

<p>Oocyte maturation refers to the transition between prophase and metaphase I in the meiotic division of oocytes.</p> Signup and view all the answers

<p>MPF induces exit from the prophase I arrest and continues to rise during the first meiotic division, contributing to meiotic progression.</p> Signup and view all the answers

<p>The decrease in MPF at the end of meiosis I is necessary for the segregation of homologous chromosomes and re-arrest of the egg at Metaphase II.</p> Signup and view all the answers

<p>CSF mediates the arrest of eggs at Metaphase II by inhibiting the anaphase-promoting complex (APC), and its inhibition is necessary for progression to fertilization and development.</p> Signup and view all the answers