Identify structure and purpose of carbohydrates, lipids, proteins, and nucleic acids - AP Biology

The primary structure of a protein is its amino acid sequence. The coils and folds of a protein are its secondary structure. Irregular contortions in the protein structure due to interactions between amino acid side chains is the tertiary structure. The overall structure when two or more polypeptides aggregated is the quaternary structure.

Disulfide bonds may be formed in both tertiary and/or quaternary structures of a protein. These bonds result from the oxidation of the R-group (side chain) of the amino acid cysteine.

Structurally speaking, a triglyceride molecule contains three fatty acid chains covalently bonded to glycerol—specifically where the hydroxyl groups are located on the glycerol molecule.

The linear sequence of amino acids in a polypeptide chain gives rise to the protein's primary structure.

RNA stands for ribonucleic acid, and each RNA nucleotide contains one phosphate, one nitrogenous base (either adenine, uracil, cytosine, or guanine), and one ribose sugar. RNA does not contain a deoxyribose sugar as seen in DNA.

The formation of disulfide bridge occurs in the tertiary and/or quaternary level of protein structure. This involves two sulfur atoms sharing a lone pair of electrons to form a covalent bond, which enhances the integrity of the protein's structure. The amino acid that is involved in forming disulfide bridges is cysteine.

The term saturated when describing a lipid means that a molecule has the maximum number of hydrogens on its carbons, it is saturated with hydrogens. An unsaturated lipid has less than the maximum amount of hydrogens bonded to its carbons because there is a double bond between two of the carbons. Lipids molecules can have one carbon to carbon double bond (mono-unsaturated) or multiple (poly-unsaturated).

Nucleotides are linked together to form nucleic acids by bonds between the phosphate groups and ribose sugars. A phosphate group is bonded the 5' carbon of one ribose and the 3' carbon of the next ribose, leading to the 5' to 3 directionality of DNA.

Fatty acids occur as free molecules in trace amounts in living organisms. They usually occur as a component of several types of lipid molecules, and are not true monomers, even though 1-3 of them can be attached to a polar head group such as glycerol or a phosphate group. The rest of the choices listed form polymers. Amino acids form proteins, sugars such as glucose form carbohydrates, and nucleotides form both DNA and RNA.

Lipids can be used as an energy source and are often used by cells to store energy for future use. Phosphate groups are not found in all lipids. For example most steroids, which are lipids, do not have phosphate groups. Lipids are hydrophobic and are repelled by water.

In saturated fats, the carbons have single bonds between them and the maximum number of hydrogen atoms. Saturated fats do not have nitrogen, and they are solid at room temperature.

Unsaturated fats have at least one double bond between two carbons in the fatty acid and do not have the maximum number of hydrogens. They do not contain nitrogen and are usually liquid at room temperature.

A nucleotide is made up of a 5-carbon sugar, a phosphate group, and a nitrogenous base. Lipids consist of a glycerol and fatty acid chains

Proteins consist of the elements nitrogen, carbon, hydrogen, and oxygen. They are polymers of molecules called amino acids. Lipids are made up of glycerol and fatty acid chains.

Proteins preform multiple functions in the body. Carrier proteins move molecules from place to place. Sometimes the molecules they carry relay signals between cells. Proteins can bind to substrates to bring the ingredients of key reactions together, catalyzing those reactions. Certain proteins integrate into cell membranes providing structural elements. Fatty acids store energy, while proteins do not. They lack the highly reduced carbon-hydrogen bonds of fatty acids.

Lipids are what make up fats. Fats store energy and help insulate animals against the cold. They also form lipid bilayers that surround cells and organelles. All steroid hormones are derived from cholesterol, a lipid. Thus, lipids play a significant role in signal transduction. Folding proteins is a function left to other proteins.

When two substrates compete for the same active site on an enzyme, it is competitive inhibition. Allosteric inhibition occurs when a substrate binds to another part of the enzyme away from the active site. Noncompetitive inhibition is another name for this. Feedback inhibition is a specific situation when the product of a reaction catalyzed by the enzyme comes back to change its function.

Cholesterol is a steroid and steroids are types of lipids. Cholesterol is common in animal cell membranes and works as a precursor for many other steroids and affects cell membrane fluidity.

Enzymatic proteins are essential to metabolic processes within the cell in that they speed up cellular reactions that would otherwise take too long. Defensive proteins help fight disease, receptor proteins respond to stimuli, motor proteins help with cell movement, and transport proteins move substances across the cell.