Understanding Proteins and Nucleic Acids - High School Biology

Proteins are composed of amino acids linked together by peptide bonds. Nucleic acids are linked by phosphodiester bonds and polysaccharides are held together by glycosidic linkages. Lipid polymers are linked by simple covalent bonds.

In DNA, guanine will always pair with cytosine (C-G) and adenine will always pair with thymine (A-T). In RNA, thymine is replaced with the pyrimidine uracil, meaning that adenine will pair with uracil in RNA (A-U). Guanine and uracil will never be paired together.

Proteins are made up of a string of amino acids. Ribosomes are responsible for facilitating the formation of covalent peptide bonds between amino acids to build the polypeptide chain. Proteins called chaperones then help fold the protein into the proper shape.

Nucleotides are found in DNA and ribonucleotides are found in RNA. Nucleosomes are small regions of DNA that are tightly wound around histone proteins. Phosphates are functional groups made of one phosphorus atom and four oxygen atoms. Phosphates are found in numerous molecules, including DNA, RNA, and phospholipids in the cell membrane, but are not generally found in proteins.

The question states that the pump transports ions against their concentration gradient. This means that this pump must use active transport. Recall that active transport requires energy in the form of ATP. ATP, or adenine triphosphate, is a type of nucleotide because it contains a nitrogenous base, a pentose sugar, and phosphate groups.

Lipids and carbohydrates (such as glucose) are the energy source for the body; however, these macromolecules themselves do not provide energy for cellular processes. They undergo metabolism and generate ATP, the molecule used by cellular processes that require energy.

Primary protein structure is the sequence of the amino acids, linked by peptide bonds. Secondary protein structure involves helices and pleated sheets formed by hydrogen bonds between backbone amino and carboxyl groups. Tertiary protein structure involves electrostatic interactions between the R groups of the amino acids in the polypeptide. The tertiary structure of a protein may be globular or filamentous, and may include disulfide bonds and/or salt bridges. Quaternary protein structure involves interactions between two or more polypeptide chains.

Enzymes are polypeptides. Polypeptides are created from proteins/amino acids. They contain a nitrogen, and have a nitrogen-carbon-carbon backbone.

Carbohydrates are referred to as polysaccharides when they form large molecules. They function as energy storage, and are responsible for the structure of plant cell walls. They are made of carbon, hydrogen, and oxygen.

Lipids in large molecules make up fats, oils, waxes, and phospholipids. They provide membrane structure, energy storage, and insulation. They are also made of carbon, hydrogen, and oxygen, and contain numerous carbon-hydrogen bonds.

Nucleic acids (DNA and RNA) are made of chains of nucleotides, bound together by phosphodiester bonds.

All amino acids have a carboxyl end, and an amino end, both of which contain the same respective atoms. The main differences in amino acids come from the different side chains contained by each amino acid.

The N terminus is the end of the protein with the amino group——exposed, and the C terminus is the end of the protein with the carboxyl group——exposed.

Proteins have six main functions: 1) movement (e.g. actin and myosin), 2) structure (e.g. keratin), 3) transport (e.g. hemoglobin), 4) protection (e.g. antibodies), 5) communication (e.g. hormones), 6) and catalyzation of chemical reactions (e.g. enzymes).

The structure of a given amino acid consists of an alpha carbon, amino group, carboxyl group, hydrogen, and a R-side group. R-side groups can have a variety of characteristics. They can be non-polar, polar, acidic, or basic. Amino acids can bond together through a peptide bond via dehydration synthesis—the loss of a single oxygen from one amino acid’s carboxyl group and two hydrogens from the other amino acid’s amine group.

Polypeptides are polymers of amino acids formed by this process. Glycerol is a component of a phospholipid.

The cysteine-cysteine disulfide bond is an example of a tertiary bond. Tertiary bonds are bonds between R-side groups. Other examples include non-polar associated bonds, polar associations with a polar aqueous environment, and ionic bonds. Primary level bonds are described as the sequence of amino acids. Secondary bonds consist of local folding due to bonds between an oxygen on a carboxyl group with a hydrogen from an amino group. This bonding includes alpha helixes and beta sheets. Quaternary bonds are defined as the association between polypeptides.

All proteins have at least a primary, secondary, and tertiary structure, but only some, such as hemoglobin, have a quaternary structure. Secondary structures are determined by hydrogen bonding between different amino acids in the polypeptide chain that form the primary structure. There may be multiple and different secondary structures in a single protein.

Amino acids link together by peptide bonds to form proteins. Nucleotides link together to form nucleic acids like DNA and RNA. Monosaccharides are sugars that form links to form carbohydrates. Fatty acids attach to a glycerol backbone to form lipids, except those that are derived from cholesterol.

Phosphorous is found in nucleotides, but not amino acids. In certain reactions, proteins can be modified by kinases to contain phosphate groups. Kinases are enzymes that catalyze the transfer of phosphate groups onto substrates. They function in signal transduction pathways.

There are only a few residues (amino acids in proteins) which can be phosphorylated: Serine, threonine, tyrosine, histidine, arginine, and lysine.