prosthetic group

Examples of prosthetic group in the following topics:

• Electron Transport Chain

  • FMN, which is derived from vitamin B2 (also called riboflavin), is one of several prosthetic groups or co-factors in the electron transport chain.
  • A prosthetic group is a non-protein molecule required for the activity of a protein.
  • Prosthetic groups can be organic or inorganic and are non-peptide molecules bound to a protein that facilitate its function.
  • Prosthetic groups include co-enzymes, which are the prosthetic groups of enzymes.
  • Cytochrome proteins have a prosthetic heme group.

• Functional Groups

  • Functional groups are groups of molecules attached to organic molecules and give them specific identities or functions.
  • Functional groups are groups of atoms that occur within organic molecules and confer specific chemical properties to those molecules.
  • A functional group can participate in specific chemical reactions.
  • Some of the important functional groups in biological molecules include: hydroxyl, methyl, carbonyl, carboxyl, amino, phosphate, and sulfhydryl groups.
  • This carboxyl group ionizes to release hydrogen ions (H+) from the COOH group resulting in the negatively charged COO- group; this contributes to the hydrophilic nature of whatever molecule it is found on.

• Amino Acids

  • An amino acid contains an amino group, a carboxyl group, and an R group, and it combines with other amino acids to form polypeptide chains.
  • Every amino acid also has another atom or group of atoms bonded to the central atom known as the R group.
  • The name "amino acid" is derived from the amino group and carboxyl-acid-group in their basic structure.
  • The carboxyl group of one amino acid is linked to the amino group of the incoming amino acid.
  • Amino acids have a central asymmetric carbon to which an amino group, a carboxyl group, a hydrogen atom, and a side chain (R group) are attached.

• 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.
  • Another example of chemical modifications affecting protein activity include the addition or removal of methyl groups.
  • 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.

• Peptide Bonding between Amino Acids

  • Amino acids are chemical compounds consisting of a carbon atom bonded to an amine group, a hydrogen atom, a carboxylic group, and a varying side-chain (R group); it is this side chain that distinguishes each amino acid from another.
  • It occurs when the carboxylic group of one molecule reacts with the amino group of the other molecule, linking the two molecules and releasing a water molecule.
  • The amide group has three resonance forms, which confer important properties.
  • First, the stabilization afforded from the resonance structures effectively stabilizes it by 80kj/mol, making it less reactive than similar groups.
  • Peptide bonds are amide bonds, characterized by the presence of a carbonyl group attached to an amine.

• Building Phylogenetic Trees

  • A phylogenetic tree sorts organisms into clades or groups of organisms that descended from a single ancestor using maximum parsimony.
  • This system sorts organisms into clades: groups of organisms that descended from a single ancestor.
  • A change in the genetic makeup of an organism leads to a new trait which becomes prevalent in the group.
  • A clade may contain multiple groups, as in the case of animals, fungi, and plants, or a single group, as in the case of flagellates.
  • Groups that diverge at a different branch point, or that do not include all groups in a single branch point, are not considered clades.

• Diversity of Angiosperms

  • Monocots include grasses and lilies while eudicots or dicots form a polyphyletic group.
  • Basal angiosperms are a group of plants that are believed to have branched off before the separation into monocots and eudicots because they exhibit traits from both groups.
  • Members in these groups all share traits from both monocot and dicot groups.
  • Familiar plants in this group include the bay laurel, cinnamon, spice bush, and avocado tree.
  • The Piperales are a group of herbs, shrubs, and small trees that grow in the tropical climates.

• Acetyl CoA to CO2

  • In the presence of oxygen, acetyl CoA delivers its acetyl group to a four-carbon molecule, oxaloacetate, to form citrate, a six-carbon molecule with three carboxyl groups.
  • During this first step of the citric acid cycle, the CoA enzyme, which contains a sulfhydryl group (-SH), is recycled and becomes available to attach another acetyl group.
  • In the citric acid cycle, the two carbons that were originally the acetyl group of acetyl CoA are released as carbon dioxide, one of the major products of cellular respiration, through a series of enzymatic reactions .
  • For each molecule of acetyl CoA that enters the citric acid cycle, two carbon dioxide molecules are released, removing the carbons from the acetyl group.

• Breakdown of Pyruvate

  • A carboxyl group is removed from pyruvate, releasing a molecule of carbon dioxide into the surrounding medium.
  • (Note: carbon dioxide is one carbon attached to two oxygen atoms and is one of the major end products of cellular respiration. ) The result of this step is a two-carbon hydroxyethyl group bound to the enzyme pyruvate dehydrogenase; the lost carbon dioxide is the first of the six carbons from the original glucose molecule to be removed.
  • The hydroxyethyl group is oxidized to an acetyl group, and the electrons are picked up by NAD+, forming NADH (the reduced form of NAD+).
  • The enzyme-bound acetyl group is transferred to CoA, producing a molecule of acetyl CoA.
  • Each pyruvate molecule loses a carboxylic group in the form of carbon dioxide.

• Cognitive Learning and Sociobiology

  • Group III rats had food available on the third day and every day thereafter.
  • 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.
  • Group II learned very slowly for the six days with no reward to motivate them.
  • 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.