control group

(noun)

a group that contains every feature of the experimental group except it is not given the manipulation that is hypothesized

Related Terms

Examples of control group in the following topics:

  • Cognitive Learning and Sociobiology

    • The results were that the control rats, Group I, learned quickly, figuring out how to run the maze in seven days.
    • Group III did not learn much during the three days without food, but rapidly caught up to the control group when given the food reward.
    • They did not begin to catch up to the control group until the day food was given; it then took two days longer to learn the maze.
    • Group I (the green solid line) found food at the end of each trial; group II (the blue dashed line) did not find food for the first 6 days; and group III (the red dotted line) did not find food during runs on the first three days.
    • Notice that rats given food earlier learned faster and eventually caught up to the control group.

  • The Scientific Method

    • Each experiment will have one or more variables and one or more controls.
    • The control group contains every feature of the experimental group except it is not given the manipulation that is hypothesized.
    • For example, a control group could be a group of varied teenagers that did not drink milk and they could be compared to the experimental group, a group of varied teenagers that did drink milk.
    • Thus, if the results of the experimental group differ from the control group, the difference must be due to the hypothesized manipulation rather than some outside factor.
    • The student could then design an experiment with a control to test this hypothesis.

  • Brain: Cerebral Cortex and Brain Lobes

    • Areas within the motor cortex map to different muscle groups; there is some organization to this map .
    • For example, the neurons that control movement of the fingers are next to the neurons that control movement of the hand.
    • Different parts of the motor cortex control different muscle groups.
    • Muscle groups that are neighbors in the body are generally controlled by neighboring regions of the motor cortex as well.
    • For example, the neurons that control shoulder movement are near the neurons that control elbow movement, which are themselves next to those that control wrist movement.

  • Cancer and Post-Transcriptional Control

    • Modifications, such as the overexpression of miRNAs, in the post-transcriptional control of a gene can result in cancer.
    • Post-transcriptional regulation is the control of gene expression at the RNA level; therefore, between the transcription and the translation of the gene.
    • After being produced, the stability and distribution of the different transcripts is regulated (post-transcriptional regulation) by means of RNA-binding proteins (RBP) that control the various steps and rates of the transcripts: events such as alternative splicing, nuclear degradation (exosome), processing, nuclear export (three alternative pathways), sequestration in DCP2-bodies for storage or degradation, and, ultimately, translation.
    • Changes in the post-transcriptional control of a gene can result in cancer.
    • Recently, several groups of researchers have shown that specific cancers have altered expression of microRNAs (miRNAs) . miRNAs bind to the 3' UTR or 5' UTR of RNA molecules to degrade them.

  • Regulator Molecules of the Cell Cycle

    • The cell cycle is controlled by regulator molecules that either promote the process or stop it from progressing.
    • In addition to the internally controlled checkpoints, there are two groups of intracellular molecules that regulate the cell cycle.
    • The second group of cell cycle regulatory molecules are negative regulators.
    • Retinoblastoma proteins are a group of tumor-suppressor proteins common in many cells.
    • Much of what is known about cell cycle regulation comes from research conducted with cells that have lost regulatory control.

  • Epigenetic Control: Regulating Access to Genes within the Chromosome

    • Nucleosomes can move to open the chromosome structure to expose a segment of DNA, but do so in a very controlled manner.
    • When unmodified, the histone proteins have a large positive charge; by adding chemical modifications, such as acetyl groups, the charge becomes less positive.
    • When this configuration exists, the cytosine member of the pair can be methylated (a methyl group is added).
    • This modification changes how the DNA interacts with proteins, including the histone proteins that control access to the region.
    • These nucleosomes control the access of proteins to the underlying DNA.

  • Citric Acid Cycle

    • CoA is bound to a sulfhydryl group (-SH) and diffuses away to eventually combine with another acetyl group.
    • The rate of this reaction is controlled by negative feedback and the amount of ATP available.
    • Steps three and four are both oxidation and decarboxylation steps, which release electrons that reduce NAD+ to NADH and release carboxyl groups that form CO2 molecules. α-Ketoglutarate is the product of step three, and a succinyl group is the product of step four.
    • CoA binds the succinyl group to form succinyl CoA.
    • A phosphate group is substituted for coenzyme A, and a high-energy bond is formed.

  • Regulating Protein Activity and Longevity

    • Proteins can be chemically modified with the addition of methyl, phosphate, acetyl, and ubiquitin groups.
    • The addition or removal of these groups from proteins regulates their activity or the length of time they exist in the cell.
    • The addition of this chemical group changes the property of the protein and, thus, affects it activity.
    • The addition of an ubiquitin group to a protein marks that protein for degradation.
    • One way to control gene expression is to alter the longevity of the protein: ubiquitination shortens a protein's lifespan.

  • Control of Catabolic Pathways

    • Catabolic pathways are controlled by enzymes, proteins, electron carriers, and pumps that ensure that the remaining reactions can proceed.
    • The control of glycolysis begins with the first enzyme in the pathway, hexokinase .
    • Phosphofructokinase is the main enzyme controlled in glycolysis.
    • If either acetyl groups or NADH accumulate, there is less need for the reaction and the rate decreases.
    • The citric acid cycle is controlled through the enzymes that catalyze the reactions that make the first two molecules of NADH .

  • Control of Homeostasis

    • The receptors sense changes in the environment, sending a signal to the control center (in most cases, the brain), which, in turn, generates a response that is signaled to an effector.
    • Homeostasis is controlled by the nervous and endocrine systems in mammals.
    • However, if an animal has not eaten and blood glucose levels decrease, this is sensed in a different group of cells in the pancreas: the hormone glucagon is released, causing glucose levels to increase.
    • Another example of an increase as a result of a feedback loop is the control of blood calcium.
    • Changes can be made in a group of body organ systems in order to maintain a set point in another system.