secondary active transport

Examples of secondary active transport in the following topics:

• Secondary Active Transport

  • In secondary active transport, a molecule is moved down its electrochemical gradient as another is moved up its concentration gradient.
  • Unlike in primary active transport, in secondary active transport, ATP is not directly coupled to the molecule of interest.
  • Both antiporters and symporters are used in secondary active transport.
  • Secondary active transport brings sodium ions, and possibly other compounds, into the cell.
  • An electrochemical gradient, created by primary active transport, can move other substances against their concentration gradients, a process called co-transport or secondary active transport.

• Primary Active Transport

  • The primary active transport that functions with the active transport of sodium and potassium allows secondary active transport to occur .
  • The secondary transport method is still considered active because it depends on the use of energy as does primary transport.
  • This difference in charge is important in creating the conditions necessary for the secondary process.
  • Primary active transport moves ions across a membrane, creating an electrochemical gradient (electrogenic transport).

• Importance of Glycolysis

  • One method is through secondary active transport in which the transport takes place against the glucose concentration gradient.
  • The other mechanism uses a group of integral proteins called GLUT proteins, also known as glucose transporter proteins.
  • These transporters assist in the facilitated diffusion of glucose.

• Electrochemical Gradient

  • To move substances against the membrane's electrochemical gradient, the cell utilizes active transport, which requires energy from ATP.
  • Because active transport mechanisms depend on a cell's metabolism for energy, they are sensitive to many metabolic poisons that interfere with the supply of ATP.
  • Primary active transport moves ions across a membrane and creates a difference in charge across that membrane, which is directly dependent on ATP.
  • Secondary active transport describes the movement of material that is due to the electrochemical gradient established by primary active transport that does not directly require ATP.
  • An important membrane adaption for active transport is the presence of specific carrier proteins or pumps to facilitate movement.

• Secondary Groups

  • Some secondary groups may last for many years, though most are short term.
  • Secondary relationships involve weak emotional ties and little personal knowledge of one another.
  • The distinction between primary and secondary groups was originally proposed by Charles Cooley.
  • A secondary group is one you have chosen to be a part of.
  • They are based on interests and activities.

• Vascular Tissue: Xylem and Phloem

  • Tracheids have thick secondary cell walls and are tapered at the ends.
  • Despite the fact that their cytoplasm is actively involved in the conduction of food materials, sieve-tube members do not have nuclei at maturity.
  • The activity of the sieve tubes is controlled by companion cells through plasmadesmata.
  • Xylem and phloem tissue make up the transport cells of stems.
  • The direction of water and sugar transportation through each tissue is shown by the arrows.

• Primary and Secondary Groups

  • These groups are marked by concern for one another, shared activities and culture, and long periods of time spent together.
  • Secondary groups are large groups whose relationships are impersonal and goal-oriented.
  • Some secondary groups may last for many years, though most are short term.
  • People in a secondary group interact on a less personal level than in a primary group.
  • Since secondary groups are established to perform functions, people's roles are more interchangeable.

• Control of Hormone Secretion

  • In essence, it is a chemical messenger that transports a signal from one cell to another.
  • Hormones in animals are often transported in the blood.
  • Hormones exit their cell of origin via exocytosis or another means of membrane transport.
  • A cell may have several different receptors that recognize the same hormone and activate different signal transduction pathways, or a cell may have several different receptors that recognize different hormones and activate the same biochemical pathway.
  • The interaction of hormone and receptor typically triggers a cascade of secondary effects within the cytoplasm of the cell, often involving phosphorylation or dephosphorylation of various other cytoplasmic proteins, changes in ion channel permeability, or increased concentrations of intracellular molecules that may act as secondary messengers (e.g., cyclic AMP).

• Routing

  • This chapter focuses on the role of routing in transportation networks.
  • Transport engineers use mathematical graph theory to analyze a transport network to determine the flow of vehicles (or people) through it.
  • A transport network may combine different modes of transport.
  • At the tactical level of supply chain activities, the transportation strategy of goods must be considered.
  • In order to reduce costs, companies often look for ways to streamline routes and supply chain activities.

• Primary and Secondary Growth in Stems

  • Plants undergo primary growth to increase length and secondary growth to increase thickness.
  • The increase in stem thickness that results from secondary growth is due to the activity of the lateral meristems, which are lacking in herbaceous plants.
  • The thickening of the stem that occurs in secondary growth is due to the formation of secondary phloem and secondary xylem by the vascular cambium, plus the action of cork cambium, which forms the tough outermost layer of the stem.
  • This supplies oxygen to the living- and metabolically-active cells of the cortex, xylem, and phloem.
  • The activity of the vascular cambium gives rise to annual growth rings.