Ch 12.1: The Cell Cycle Flashcards
What occurs during prophase?
The chromatin become tightly coiled into chromosomes, the nucleoli disappear, mitotic spindles begin to form from the aster, and the centrosomes move away from eachother
What occurs during prometaphase?
the nuclear envelope fragments, the chromosomes have become even more condensed, microtubules have attached to the kinetochores, and nonkinetochore microtubules interact with those from the opposite pole of the spindle, lengthening the cell
What occurs during metaphase?
the centrosomes are now at opposite poles of the cell and the chromosomes have arrived at the metaphase plate
What occurs during anaphase?
shortest stage, sister chromosomes are pulled apart and begin moving toward opposite ends of the cell, and the cell elongates as the nonkinetochore microtubules lengthen
What occurs during telophase?
two daughter nuclei form in the cell, nuclear envelopes arise from the fragments of the parent cell’s nuclear envelopes, nucleoli reappear, chromosomes become less condensed, and any remaining spindle microtubules are depolymerized
What occurs during cytokenisis?
in animal cells, cytokinesis involves that formation of a cleavage furrow, which pinches the cell in two
What is a mitotic spindle?
a structure made of microtubules that controls chromosome movement during mitosis
What is a centrosome?
a type of microtubule-organizing center where the assembly of spindle microtubules begins
When do centrosomes replicate?
during interphase
What are kinetochore?
a protein complex associated with centromeres
What is the metaphase plate?
an imaginary plane midway between the spindle’s two poles
How are microtubules shortened?
motor proteins “walk” or “reel” the chromosomes along the microtubules
What forms during cytokinesis for plant cells?
a cell plate
How do prokaryotes reproduce?
with binary fission
What occurs during binary fission?
the chromosome replicates (beginning at the origin of replication), and then two daughter chromosomes actively move apart, the plasma membrane pinches inward, dividing the cell in two
What is the cycle control system?
it directs the events of the cell cycle by both internal and external controls with specific checkpoints where the cell cycle stops until a go-ahead signal is received
What are two types of regulatory proteins that are involved in cell cycle control?
cyclins and cyclin-dependent kinases (Cdks)
What is a MPF (maturation-promoting factor)?
a cyclin-Cdk complex that triggers a cell’s passage past the G2 checkpoint into the Mphase
What happens if a cell does not receive a go-ahead signal at the G1 checkpoint?
it will exit the cycle, switching into a nondividing state called the G0 phase
What are growth factors?
they are released by certain cells and stimulate other cells to divide (external factor)
What is density-dependent inhibition?
crowded cells will stop dividing
What is anchorage dependence?
for animal cells to divide, they must be attached to a substratum
Both density-dependent inhibition and anchorage dependence check:
the growth of cells at an optimal density
What happens to a cell that undergoes transformation?
cells now have the ability to divide indefinitely
What is a benign tumor?
abnormal cells that remain at the original site
What is a malignant tumor?
abnormal cells that invade surrounding tissues
What is metastasis?
the spread of cancer cells to other parts of the body, where they may form additional tumors
