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By the end of this section, you will be able to:
  • Describe how feedback inhibition would affect the production of an intermediate or product in a pathway
  • Identify the mechanism that controls the rate of the transport of electrons through the electron transport chain

Cellular respiration must be regulated in order to provide balanced amounts of energy in the form of ATP. The cell also must generate a number of intermediate compounds that are used in the anabolism and catabolism of macromolecules. Without controls, metabolic reactions would quickly come to a stand still as the forward and backward reactions reached a state of equilibrium. Resources would be used inappropriately. A cell does not need the maximum amount of ATP that it can make all the time: At times, the cell needs to shunt some of the intermediates to pathways for amino acid, protein, glycogen, lipid, and nucleic acid production. In short, the cell needs to control its metabolism.

Regulatory mechanisms

A variety of mechanisms is used to control cellular respiration. Some type of control exists at each stage of glucose metabolism. Access of glucose to the cell can be regulated using the GLUT proteins that transport glucose ( [link] ). Different forms of the GLUT protein control passage of glucose into the cells of specific tissues.

When insulin in the bloodstream binds the insulin receptor in the plasma membrane of a target cell, a vesicle containing the glucose transporter Glut-4 fuses with the plasma membrane. Glut-4 is a transporter that allows glucose to enter the cell.
GLUT4 is a glucose transporter that is stored in vesicles. A cascade of events that occurs upon insulin binding to a receptor in the plasma membrane causes GLUT4-containing vesicles to fuse with the plasma membrane so that glucose may be transported into the cell.

Some reactions are controlled by having two different enzymes—one each for the two directions of a reversible reaction. Reactions that are catalyzed by only one enzyme can go to equilibrium, stalling the reaction. In contrast, if two different enzymes (each specific for a given direction) are necessary for a reversible reaction, the opportunity to control the rate of the reaction increases, and equilibrium is not reached.

A number of enzymes involved in each of the pathways—in particular, the enzyme catalyzing the first committed reaction of the pathway—are controlled by attachment of a molecule to an allosteric site on the protein. The molecules most commonly used in this capacity are the nucleotides ATP, ADP, AMP, NAD + , and NADH. These regulators, allosteric effectors, may increase or decrease enzyme activity, depending on the prevailing conditions. The allosteric effector alters the steric structure of the enzyme, usually affecting the configuration of the active site. This alteration of the protein’s (the enzyme’s) structure either increases or decreases its affinity for its substrate, with the effect of increasing or decreasing the rate of the reaction. The attachment signals to the enzyme. This binding can increase or decrease the enzyme’s activity, providing feedback. This feedback type of control is effective as long as the chemical affecting it is attached to the enzyme. Once the overall concentration of the chemical decreases, it will diffuse away from the protein, and the control is relaxed.

Questions & Answers

what is oxidation?
Rose Reply
 the state or result of being oxidized
hahahaha thanks, but my teachers requires a thorough meaning about that
Is the process of oxidizing ,the addition of oxygen to a compound with a loss of electrons, always accompanied by reduction
loss of electron....
thank you. 😊
thank you. 😊
thank you. 😊
what is oxidized
the process or result of oxidizing or being oxidized.
what is genetic
Chibawa Reply
name the enzymes that i found in the saliva
Valuables Reply
draw a bacterium cell and label
Kadijah Reply
What are the osmoregulatory functions of the kidney?
bisi Reply
What is ecology
Hebert Reply
what is cell
Etama Reply
cell is the basic unit of life
cell is the basic structural and functional unit of an living organism
a cell is the smallest and most basic unit of a living thing
cell is the basic unit of life. we are made up of 60,000 billions of cells.Each cell carry out a specific function in the body.
A cell is the smallest basic functioning unit of life.
where is the pectoral gridle located?
Tiania Reply
What is hypotonic
Bright Reply
what is hypotonic
Hypotonic means weak solution
the difference between the two cells
Obeng Reply
explain the courses and the correction of lon term sightedness and short term sightedness
Isaac Reply
long sightedness is said to be like someone that can see far object clearly why short sightedness is someone that only can see near obect
why drinking excess alcohol causes thirst and dehydration
uwikuzo Reply
Can we chat about nutrition please?
Uhm why is it so important to follow the nutritional process?
BC it contribute to the source of life
what is reproduction
smart Reply
it is d act of bringing young ones to life
to ensure survival of a species🚴‍♀️
what is a genotype
what is hazardous
a cell is the smallest unit of a living thing. so we all have cell
It is the formation of a zygote resulting from the fusion of the sperm cell with the ovum.Thus,this results in the production of new species which are genetically dissimilar from their parent cells.
yes we all have cell round our body without the existances of cell them they will be no life in us as human
what is size of cell
Mohd Reply
what is size of Hart
nanometers=um sign thingie
monomers and polymers of nucleic acids?
Jyrl Reply
dna and rna involvement

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Source:  OpenStax, Biology. OpenStax CNX. Feb 29, 2016 Download for free at http://cnx.org/content/col11448/1.10
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