Krishnan

Question 1

Define Saddle Node Bifurcation

Answer 1

When there is a transition from 0 to 2 steady states as a parameter changes sign

Question 2

Define Steady State Stability

Answer 2

Deviating away from the steady state will result in a return towards the steady state

Question 3

Define Asymptotic Stability

Answer 3

If located within a certain vicinity of the the steady state point, are guarenteed to return to that point

Question 4

Define Transcritical Bifurcation

Answer 4

Exchange of stability between the two steady states when the parameter changes sign

Question 5

Define Pitchfork Bifurcation

Answer 5

Transition from 1 to 3 steady states as the parameter changes sign

Question 6

Define Supercritical Pitchfork Bifurcation

Answer 6

Transition from 1 to 3 steady states as the parameter changes sign where both the arcs are stable, and the zero steady state is unstable

Question 7

Define Subcritical Pitchfork Bifurcation

Answer 7

Transition from 1 to 3 steady states as the parameter changes sign where both the arcs are unstable, and the zero steady state is stable

Question 8

Define Supercritical Hoff Bifurcation

Answer 8

Transition from 1 stable steady state at zero to 2 steady states: an unsteady state at zero and a stable (from birth) non zero steady state which branches out from zero

Question 9

Define Subcritical Hoff Bifurcation

Answer 9

Transition from 1 stable steady state at zero to 2 steady states: an unsteady state at zero and a stable non zero steady state. However at their birth both are unstable, but the non-zero steady state is an oscillatory steady state which once beyond a certain value is stable

Question 10

Define the unsaturated limit

Answer 10

The enzyme is in excess or the catalytic rate is high such that the enzyme is assumed all to be free and the complex concentration approaching zero. (i.e. [E]t = [E] & [ES] = 0).

Question 11

Define a Hill Function

Answer 11

sigmoidal function with a steep increase at a particular between 2 “x” values. Switch-like behaviour

Question 12

Define Bistable Switch

Answer 12

Associated with a saddle-node bifurcation. Hysteresis of the steady states. Therefore 3 steady states for one parameter value. Middle steady state is very unstable.

Question 13

Define linear direct feedback

Answer 13

Feedback where the rate of change of x is directly proportional to x

Question 14

Define non-linear feedback

Answer 14

Rate of change of x is proportional to a non linear function of x

Question 15

Define Retroactivity

Answer 15

System where downstream species can affect upstream reactions

Question 16

Define Bistability

Answer 16

Multiple steady states at one parameter value

Question 17

Define Co-operativity

Answer 17

The affect of one promoter binding to a promoter site has on the rate of another promoter binding to a different site

Question 18

Auto-inhibition

Answer 18

The mutual repression of multiple gene/protein elements in sequence