growth phase transitions

Examples of growth phase transitions in the following topics:

• Solid to Gas Phase Transition

  • Sublimation is the phase transition from the solid to the gaseous phase, without passing through an intermediate liquid phase.
  • Sublimation is the process of transformation directly from the solid phase to the gaseous phase, without passing through an intermediate liquid phase.
  • It is an endothermic phase transition that occurs at temperatures and pressures below a substance's triple point (the temperature and pressure at which all three phases coexist) in its phase diagram.
  • In these cases, the transition from the solid to the gaseous state requires an intermediate liquid state.
  • But at temperatures below that of the triple point, a decrease in pressure will result in a phase transition directly from the solid to the gaseous.

• Liquid to Solid Phase Transition

  • Freezing is a phase transition in which a liquid turns into a solid when its temperature is lowered to its freezing point.
  • Freezing, or solidification, is a phase transition in which a liquid turns into a solid when its temperature is lowered to or below its freezing point.
  • This is a first-order thermodynamic phase transition, which means that as long as solid and liquid coexist, the equilibrium temperature of the system remains constant and equal to the melting point.
  • Crystallization consists of two major events: nucleation and crystal growth.
  • The crystal growth is the subsequent growth of the nuclei that succeed in achieving and surpassing the critical cluster size.

• Major Features of a Phase Diagram

  • A phase diagram is a graph which shows under what conditions of temperature and pressure distinct phases of matter occur.
  • The simplest phase diagrams are of pure substances.
  • The major features of a phase diagram are phase boundaries and the triple point.
  • In this phase diagram, which is typical of most substances, the solid lines represent the phase boundaries.
  • The green line marks the freezing point (or transition from liquid to solid), the blue line marks the boiling point (or transition from liquid to gas), and the red line shows the conditions under which a solid can be converted directly to a gas (and vice-versa).

• Interpreting Phase Diagrams

  • The lines that separate these single phase regions are known as phase boundaries.
  • By focusing attention on distinct single phase regions, phase diagrams help us to understand the range over which a particular pure sample of matter exists as a particular phase.
  • When evaluating the phase diagram, it is worth noting that the solid-liquid phase boundary in the phase diagram of most substances has a positive slope.
  • With a knowledge of the major components of phase diagrams and the features of phase plots, a phase diagram can be used to understand how altering thermodynamic parameters influences the states/phases of matter a sample of a substance is in.
  • The thermodynamic properties of mothballs, made of 1,4-Dichlorobenzene, are used to repel insects. 1,4- Dichlorobenzene sublimates (transitions from solid to gas) at room temperature.

• Generation Time

  • In autecological studies, bacterial growth in batch culture can be modeled with four different phases: lag phase, exponential or log phase, stationary phase, and death phase .
  • During lag phase, bacteria adapt themselves to growth conditions.
  • During this phase of the bacterial growth cycle, synthesis of RNA, enzymes, and other molecules occurs.
  • The exponential phase (sometimes called the log phase or the logarithmic phase) is a period characterized by cell doubling.
  • The phases of growth are labelled on top.

• Regulation of the Cell Cycle at Internal Checkpoints

  • These checkpoints occur near the end of G1, at the G2/M transition, and during metaphase .
  • External influences, such as growth factors, play a large role in carrying the cell past the G1 checkpoint.
  • A cell that does not meet all the requirements will not progress to the S phase.
  • This transition, as with all of the major checkpoint transitions in the cell cycle, is signaled by cyclins and cyclin dependent kinases (CDKs).
  • The G2 checkpoint bars entry into the mitotic phase if certain conditions are not met.

• Phase Changes and Energy Conservation

  • During a phase transition, certain properties of the medium change, often discontinuously, as a result of some external condition.
  • During a phase transition of a given medium certain properties of the medium change, often discontinuously, as a result of some external condition, such as temperature or pressure.
  • The measurement of the external conditions at which the transformation occurs is termed the phase transition.
  • The term is most commonly used to describe transitions between solid, liquid and gaseous states of matter and, in rare cases, plasma.
  • There are well-defined regions on these graphs that correspond to various phases of matter, so PT graphs are called phase diagrams .

• The Evaporating Atmosphere

  • Within each phase, the properties are uniform but between the two phases properties differ.
  • Even at equilibrium, molecules are constantly in motion and, once in a while, a molecule in the liquid phase gains enough kinetic energy to break away from the liquid phase and enter the gas phase.
  • If the liquid is heated a little over 100 °C, the transition from liquid to gas will occur not only at the surface, but throughout the liquid volume: the water boils.
  • The water vapor in it changes phases.
  • It is in a phase equilibrium.

• Liquid to Gas Phase Transition

  • Vaporization of a sample of liquid is a phase transition from the liquid phase to the gas phase.
  • Vaporization of a sample of liquid is a phase transition from the liquid phase to the gas phase.
  • Gradually, Pw will rise as molecules escape from the liquid phase and enter the vapor phase.
  • At the same time, some of the vapor molecules will condense back into the liquid phase (step 2).
  • This video looks at how vaporization and evaporation happens, and it addresses a big mistake that many people make when they deal with the liquid gas phase transition.

• Interphase

  • During interphase, the cell undergoes normal growth processes while also preparing for cell division.
  • The centrosome is duplicated during the S phase.
  • There may be additional cell growth during G2.
  • The cell cycle consists of interphase and the mitotic phase.
  • Interphase is followed by the mitotic phase.