Kapitel 18 Flashcards
Stage of mitosis during which the two sets of chromosomes separate and are pulled toward opposite ends of the dividing cell.
anaphase
A protein complex that triggers the separation of sister chromatids and orchestrates the carefully timed destruction of proteins that control progress through the cell cycle; the complex catalyzes the ubiquitylation of its targets.
anaphase-promoting complex (APC)
A tightly controlled form of programmed cell death that allows cells that are unneeded or unwanted to be eliminated from an adult or developing organism.
apoptosis
Star-shaped array of microtubules emanating from a centrosome or from a pole of a mitotic spindle.
aster
Related group of intracellular proteins that regulates apoptosis; some family members promote cell death - others inhibit it.
Bcl2 family
The symmetrical attachment of a sister chromatid pair on the mitotic spindle - such that one chromatid in the duplicated chromosome is attached to one spindle pole and the other is attached to the opposite pole.
bi-orientation
A family of proteases that - when activated - mediates the destruction of the cell by apoptosis.
caspase
Regulatory protein that blocks the assembly or activity of cyclin–Cdk complexes - delaying progression primarily through the G1 and S phases of the cell cycle.
Cdk inhibitor protein
Network of regulatory proteins that govern the orderly progression of a eukaryotic cell through the stages of cell division.
cell-cycle control system
Process by which the centrosome duplicates (during interphase) and the two new centrosomes separate (at the beginning of mitosis) to form the poles of the mitotic spindle.
centrosome cycle
Mechanism by which the cell-cycle control system can regulate progression through the cycle - ensuring that conditions are favorable and each process has been completed before proceeding to the next stage.
checkpoint
Process by which a duplicated chromosome becomes packed into a more compact structure prior to cell division.
chromosome condensation
Protein complex that holds sister chromatids together after DNA has been replicated in the cell cycle.
cohesin
Protein complex that helps configure duplicated chromosomes for segregation by making them more compact.
condensin
Structure made of actin and myosin filaments that forms a belt around a dividing cell - pinching it in two.
contractile ring
Regulatory protein whose concentration rises and falls at specific times during the eukaryotic cell cycle; cyclins help control progression from one stage of the cell cycle to the next by binding to cyclin-dependent protein kinases (Cdks).
cyclin
Enzyme that - when complexed with a regulatory cyclin protein - can trigger various events in the cell-division cycle by phosphorylating specific target proteins.
cyclin-dependent protein kinase (Cdk)
Process by which the cytoplasm of a plant or animal cell divides in two to form individual daughter cells.
cytokinesis
Regulatory protein that helps drive a cell through the first gap phase of the cell cycle and toward S phase.
G1 cyclin
Gap 1 phase of the eukaryotic cell cycle; falls between the end of cytokinesis and the start of DNA synthesis.
G1 phase
Protein complex whose activity drives the cell through the first gap phase of the cell cycle; consists of a G1 cyclin plus a cyclin-dependent protein kinase (Cdk).
G1-Cdk
Regulatory protein that helps to launch the S phase of the cell cycle.
G1/S cyclin
Protein complex whose activity triggers entry into S phase of the cell cycle; consists of a G1/S cyclin plus a cyclin-dependent protein kinase (Cdk).
G1/S-Cdk
Gap 2 phase of the eukaryotic cell cycle; falls between the end of DNA synthesis and the beginning of mitosis.
G2 phase
Extracellular signaling molecule that stimulates a cell to increase in size and mass. Examples include epidermal growth factor (EGF) and platelet-derived growth factor (PDGF).
growth factor
Long period of the cell cycle between one mitosis and the next. Includes G1 phase - S phase - and G2 phase.
interphase
Protein complex that assembles on the centromere of a condensed mitotic chromosome; the site to which spindle microtubules attach.
kinetochore
Regulatory protein that binds to mitotic Cdk to form M-Cdk - the protein complex that triggers the M phase of the cell cycle.
M cyclin
Period of the eukaryotic cell cycle during which the nucleus and cytoplasm divide.
M phase
Protein complex that triggers the M phase of the cell cycle; consists of an M cyclin plus a mitotic cyclin-dependent protein kinase (Cdk).
M-Cdk
Stage of mitosis in which chromosomes are firmly attached to the mitotic spindle at its equator but have not yet segregated toward opposite poles.
metaphase
An extracellular signal molecule that stimulates cell proliferation.
mitogen
Division of the nucleus of a eukaryotic cell.
mitosis
Array of microtubules and associated molecules that forms between the opposite poles of a eukaryotic cell during mitosis and pulls duplicated chromosome sets apart.
mitotic spindle
Transcription regulator that controls the cell’s response to DNA damage - preventing the cell from entering S phase until the damage has been repaired or inducing the cell to commit suicide if the damage is too extensive; mutations in the gene encoding this protein are found in many human cancers.
p53
In a dividing plant cell - structure made of microtubules and membrane vesicles that guides the formation of a new cell wall.
phragmoplast
A tightly controlled form of cell suicide that allows cells that are unneeded or unwanted to be eliminated from an adult or developing organism; also called apoptosis.
programmed cell death
Stage of mitosis in which the nuclear envelope breaks down and duplicated chromosomes are captured by the spindle microtubules; precedes metaphase.
prometaphase
First stage of mitosis - during which the duplicated chromosomes condense and the mitotic spindle forms.
prophase
Regulatory protein that helps to launch the S phase of the cell cycle.
S cyclin
Period during a eukaryotic cell cycle in which DNA is synthesized.
S phase
Protein complex whose activity initiates DNA replication; consists of an S cyclin plus a cyclin-dependent protein kinase (Cdk).
S-Cdk
Copy of a chromosome - produced by DNA replication - that remains bound to the other copy.
sister chromatid
Centrosome from which microtubules radiate to form the mitotic spindle.
spindle pole
Extracellular signal molecule that must be present to suppress apoptosis.
survival factor
Final stage of mitosis in which the two sets of separated chromosomes decondense and become enclosed by a nuclear envelope.
telophase
See anaphase-promoting complex
APC
Separation of a cell into two daughter cells. In eukaryotic cells - entails the splitting of the nucleus (mitosis) closely followed by cleavage of the cytoplasm (cytokinesis).
cell division
See sister chromatid
chromatid
See chromosome condensation
condensation
Assembly of proteins that is bound to the DNA at origins of replication in eukaryotic chromosomes throughout the cell cycle.
origin recognition complex (ORC)
During cell division - the process by which duplicated chromosomes are organized and then separated into the chromosome sets that will be inherited by each of the daughter cells.
segregation
Protein complex in centrosomes from which microtubules grow.
γ-tubulin ring
