Biology Reference
In-Depth Information
TABLE 14.1
Glossary
a
Factor
A budding yeast pheromone that induces mating of haploid strains of opposite mating types (a and
a
).
Aneuploid
Having an unbalanced genome, with too few or too many copies of some chromosomes or sub-chromosomal
regions.
Bifurcation point
A point in parameter space where a dynamical system undergoes a qualitative change in long-term behavior
(e.g., from monostability to bistability).
Bistability
A dynamical system that has two stable steady states for physically realistic values of its variables (0
x
i
x
i,max
).
Centromere
The region of a replicated chromosome where the two sister chromatids are held together by cohesin rings in
prometaphase.
Checkpoint
A molecular mechanism that detects problems in cell cycle processes and prevents progression to later events
until the earlier processes can be successfully completed.
Coupled reactions
A chemical reaction (R1) can be made to proceed in the non-spontaneous direction (
D
G
1
>
0) by coupling it to
a spontaneous reaction (R2;
D
G
2
<
0) in such a way that
D
G
coupled
¼ D
G
1
þ D
G
2
<
0.
Dynamic system
A system of interacting components (e.g., genes and proteins) that undergoes changes in time (and possibly also
in space); in a continuous dynamical system, those changes can be described by a set of coupled differential
equations.
Irreversibility,
thermodynamic
At constant temperature and pressure, a non-equilibrium chemical reaction will proceed spontaneously
(irreversibly) in the direction for which
D
G
<
0.
Irreversibility,
dynamic
A transition in a dynamical system from one stable solution to another that is induced by a parameter change
through a bifurcation point and that cannot be reversed by a small change in the parameter value in the opposite
direction.
Kinetochore
The docking site for microtubules in the centromeric region of a chromatid.
Monostability
A dynamical system that has only one stable steady state for physically realistic values of its variables (0
x
i
x
i,max
).
Nullcline
The locus of points in the phase plane where f(x,y)
¼
0org(x,y)
¼
0.
One-parameter
bifurcation diagram
Plot of the steady state value of a dynamical variable as a function of a parameter of the dynamical system.
Parameter
A constant used to define the rate expression on the right-hand-side of a differential equation, e.g., the rate
constant of a chemical reaction.
Phase plane
The state space of a two-variable dynamical system; dx/dt
¼
f(x,y), dy/dt
¼
g(x,y).
Proteosome
A multiprotein complex that functions as the cell's garbage disposal unit, capturing polyubiquitinated proteins
and hydrolyzing them.
Restriction point
A point-of-no-return in G1 phase of the mammalian cell cycle with respect to removal of growth factor.
Reversibility, equilibrium All chemical reactions are intrinsically reversible, and at equilibrium the forward and reverse reactions are
occurring at the same rate.
Saddle-node bifurcation
A bifurcation point where a stable node and an unstable saddle point coalesce and annihilate each other.
Steady state
A constant solution {x(t)
¼
x
o
, y(t)
¼
y
o
} of a dynamical system with the property that f(x
o
,y
o
)
¼
0 and
g(x
o
,y
o
)
¼
0.
Steady state, stable
A constant solution of a dynamical system with the property that any small perturbation away from the steady
state grows smaller as time proceeds.
Steady state, unstable
A constant solution of a dynamical system with the property that some small perturbations away from the steady
state grow larger as time proceeds.
Stochastic
Random fluctuations in the number of molecules of a chemical species due to the probabilistic nature of
chemical reactions.
