What are the monomers and polymers of protein? | Socratic
Monomers are small, simple molecules that can be joined together to form polymers. Example of polymer. Monomer. Bonds. Monomers: Key monomers to learn easy because there's only one difference between them, as the diagram below. Answer to: Explain the relationship between monomers and polymers. By signing up, you'll get thousands of step-by-step solutions to your homework.
Three extended helices of a type called polyproline II helices because polyproline can take this form hydrogen bonded to one another interchain ; no intrachain hydrogen bonds form because each helix is too extended, and hydrogen bonds cannot reach from one level of the helix up or down to the next level placed at the corners of a triangle.
The entire assembly is twisted into a superhelix. The stability of the collagen triple helix is due to its unusual amino acid composition and sequence. One third of the amino acid residues is glycine, and the glycyl residues are evenly spaced: Gly X Y n, where X and Y are other amino acids is the amino acid sequence of collagen. This places a glycyl residue at each position where the chain is in the interior of the triple helix.
There would be no room for a bulky R-group in this position glycine's R-group is H. The high glycine content with its small R-group would otherwise permit too much conformational freedom and favor a random coil.
- What is the relationship between monomers and polymers? Give an example using proteins.
- 3.1: Synthesis of Biological Macromolecules
- What are some examples of monomers and polymers?
Proline and hydroxyproline together comprise about one third of the total amino acid residues, and Gly Pro Hypro is a common sequence. The relative inflexibility of the prolyl and hydroxyprolyl residues stiffens the chains.
Collagen occurs in tough, inelastic tissues, like tendon. The collagen helix is already fully extended. Unlike the alpha-helix, it cannot stretch; tendon ought not to stretch under heavy load.
Introduction to macromolecules
Collagen is the single most abundant protein in the body; fortunately collagen defects are rare. Tertiary structure is the three dimensional arrangement of helical and nonhelical regions of macromolecules. Let's look first at the Tertiary structure of nucleic acids. Most circular double-stranded DNA is partly unwound before the ends are sealed to make the circle. Partial unwinding is called negative superhelicity. Overwinding before sealing would be called positive superhelicity.
Superhelicity introduces strain into the molecule. Think of holding a coil spring by the two ends and twisting it to unwind it; it takes effort to introduce this strain The strain of superhelicity can be relieved by forming a supercoil. The identical phenomenon occurs in retractable telephone headset cords when they get twisted.
The twisted circular DNA is said to be supercoiled.
The supercoil is more compact. This is exemplified by yeast tRNA. There are four regions in which the strand is complementary to another sequence within itself. These regions are antiparallel, fulfilling the conditions for stable double helix formation. X-ray crystallography shows that the three dimensional structure of tRNA contains the expected double helical regions.
Large RNA molecules have extensive regions of self-complementarity, and are presumed to form complex three-dimensional structures spontaneously. Tertiary structure in Proteins The formation of compact, globular structures is governed by the constituent amino acid residues.
Folding of a polypeptide chain is strongly influenced by the solubility of the amino acid R-groups in water.
Hydrophobic R-groups, as in leucine and phenylalanine, normally orient inwardly, away from water or polar solutes. Polar or ionized R-groups, as in glutamine or arginine, orient outwardly to contact the aqueous environment. Some amino acids, such as glycine, can be accommodated by aqueous or nonaqueous environments. The rules of solubility and the tendency for secondary structure formation determine how the chain spontaneously folds into its final structure.
Forces stabilizing protein tertiary structure. Hydrophobic interactions -- the tendency of nonpolar groups to cluster together to exclude water. Hydrogen bonding, as part of any secondary structure, as well as other hydrogen bonds. Ionic interactions -- attraction between unlike electric charges of ionized R-groups. Disulfide bridges between cysteinyl residues. The disulfide bridge is a covalent bond.
It strongly links regions of the polypeptide chain that could be distant in the primary sequence.
It forms after tertiary folding has occurred, so it stabilizes, but does not determine tertiary structure. Globular proteins are typically organized into one or more compact patterns called domains. This concept of domains is important. In general it refers to a region of a protein. But it turns out that in looking at protein after protein, certain structural themes repeat themselves, often, but not always in proteins that have similar biological functions.
This phenomenon of repeating structures is consistent with the notion that the proteins are genetically related, and that they arose from one another or from a common ancestor. In looking at the amino acid sequences, sometimes there are obvious homologies, and you could predict that the 3-dimensional structures would be similar. But sometimes virtually identical 3-dimensional structures have no sequence similarities at all!
The four-helix bundle domain is a common pattern in globular proteins.
Introduction to macromolecules (article) | Khan Academy
Helices lying side by side can interact favorably if the properties of the contact points are complementary. Hydrophobic amino acids like leucine at the contact points and oppositely charged amino acids along the edges will favor interaction. If the helix axes are inclined slightly 18 degreesthe R-groups will interdigitate perfectly along 6 turns of the helix. Sets of four helices yield stable structures with symmetrical, equivalent interactions.
Interestingly, four-helix bundles diverge at one end, providing a cavity in which ions may bind. All-beta structures comprise domains in many globular proteins. Beta-pleated sheets fold back on themselves to form barrel-like structures.
Part of the immunoglobulin molecule exemplifies this. The interiors of beta-barrels serve in some proteins as binding sites for hydrophobic molecules such as retinol, a vitamin A derivative. What keeps these proteins from forming infinitely large beta-sheets is not clear. They consist of a beta-barrel surrounded by a wheel of alpha-helices. Examples Triose phosphate isomerase.
Domain 1 of pyruvate kinase. Beta-sheet surrounded by alpha-helices also occur. This is a variation on the theme of beta-structure inside and alpha-helix outside. Examples Lactate dehydrogenase domain 1 Phosphoglycerate kinase domain 2 Now that we are familiar with the structures of single chain macromolecules, we are in a position to look at some of the interactions of macromolecules with other macromolecules and with smaller molecules.
Macromolecular interactions involving proteins. Quaternary structure refers to proteins formed by association of polypeptide subunits. Individual globular polypeptide subunits may associate to form biologically active oligomers. The association is specific.
A limited number of subunits is involved. At the same time, the monomers share electrons and form covalent bonds. As additional monomers join, this chain of repeating monomers forms a polymer.
Different types of monomers can combine in many configurations, giving rise to a diverse group of macromolecules.
Even one kind of monomer can combine in a variety of ways to form several different polymers: During these reactions, the polymer is broken into two components: In the hydrolysis reaction shown here, the disaccharide maltose is broken down to form two glucose monomers with the addition of a water molecule.
These reactions are similar for most macromolecules, but each monomer and polymer reaction is specific for its class. For example, in our bodies, food is hydrolyzed, or broken down, into smaller molecules by catalytic enzymes in the digestive system.
This allows for easy absorption of nutrients by cells in the intestine. Each macromolecule is broken down by a specific enzyme. One of the glucose molecules loses an H, the other loses an OH group, and a water molecule is released as a new covalent bond forms between the two glucose molecules. As additional monomers join by the same process, the chain can get longer and longer and form a polymer. Even though polymers are made out of repeating monomer units, there is lots of room for variety in their shape and composition.
Carbohydrates, nucleic acids, and proteins can all contain multiple different types of monomers, and their composition and sequence is important to their function. For instance, there are four types of nucleotide monomers in your DNAas well as twenty types of amino acid monomers commonly found in the proteins of your body.
Even a single type of monomer may form different polymers with different properties. For example, starch, glycogen, and cellulose are all carbohydrates made up of glucose monomers, but they have different bonding and branching patterns. Hydrolysis How do polymers turn back into monomers for instance, when the body needs to recycle one molecule to build a different one?
Polymers are broken down into monomers via hydrolysis reactions, in which a bond is broken, or lysed, by addition of a water molecule.
During a hydrolysis reaction, a molecule composed of multiple subunits is split in two: This is the reverse of a dehydration synthesis reaction, and it releases a monomer that can be used in building a new polymer.
For example, in the hydrolysis reaction below, a water molecule splits maltose to release two glucose monomers.