Biological Molecules

These flashcards cover key vocabulary related to biological molecules, including definitions of important terms and concepts in biochemistry.

Organic Molecules

Molecules that generally contain carbon skeletons with various chemical groups attached that confer different properties.

Dehydration Reaction

A type of reaction that builds polymers by removing water.

Hydrolysis Reaction

A type of reaction that breaks down polymers by adding water.

Carbohydrates

Biological molecules that serve as energy sources and structural components.

Monosaccharides

The simplest carbohydrates, consisting of single sugar molecules like glucose and fructose.

Disaccharides

Carbohydrates formed from two monosaccharide units, such as sucrose and maltose.

Polysaccharides

Large carbohydrate molecules composed of many monosaccharide units as in starch and cellulose.

Lipids

A class of biological molecules that includes fats and steroids, which are hydrophobic.

Phospholipid

A type of lipid that forms the structural basis of cell membranes, consisting of hydrophilic heads and hydrophobic tails.

Proteins

Polymers made of amino acids that serve various functions in living organisms, including enzymes and structural components.

Amino Acids

The building blocks of proteins, characterized by a central carbon, an amino group, a carboxyl group, a hydrogen atom, and a variable R group.

Peptide Bond

The covalent bond formed between amino acids during protein synthesis.

Nucleic Acids

Macromolecules that store and transmit genetic information, including DNA and RNA.

Nucleotide

The monomer unit of nucleic acids, consisting of a sugar, a phosphate group, and a nitrogenous base.

Cis Fatty Acids

Unsaturated fatty acids that have hydrogen atoms on the same side of the double bond.

Trans Fatty Acids

Unsaturated fatty acids that have hydrogen atoms on opposite sides of the double bond, often created through hydrogenation.

Denaturation

The alteration of a protein's structure due to environmental changes, affecting its function.

Quaternary Structure

The highest level of protein structure, formed by the assembly of multiple polypeptide chains.

Primarily Structure

The unique sequence of amino acids in a protein.

Secondary Structure

The localized folding of a polypeptide chain into structures such as alpha helices or beta pleated sheets.

Tertiary Structure

The overall three-dimensional shape of a protein, determined by interactions among side chains.

Sugar-Phosphate Backbone

The structural framework of nucleic acids formed by alternating sugar and phosphate groups.

Organic Molecules

Molecules that primarily contain carbon and hydrogen, often forming complex carbon skeletons. These molecules are typically associated with living organisms and have various functional groups (such as hydroxyl or amino groups) that determine their chemical properties and reactivity.

Dehydration Reaction

A chemical process where two monomers are covalently bonded to each other with the simultaneous removal of a water molecule ($H_{2}O$). This reaction is the primary mechanism for building polymers from simpler subunits.

Hydrolysis Reaction

A chemical reaction that breaks the covalent bonds between monomers in a polymer by adding a water molecule ($H_{2}O$). One part of the molecule gains a hydrogen atom ($H+$), while the other gains a hydroxyl group ($OH-$).

Carbohydrates

Biological macromolecules composed of carbon, hydrogen, and oxygen, often in a ratio of $1:2:1$. They function as primary sources of short-term dietary energy and serve as structural materials in plants (cellulose) and arthropods (chitin).

Monosaccharides

The simplest form of carbohydrates, also known as simple sugars. Examples include Glucose ($C<em>{6}H</em>{12}O_{6}$) and Fructose. They serve as the fuel for cellular work and as the building blocks for more complex sugars.

Disaccharides

Carbohydrates composed of two monosaccharides joined by a glycosidic linkage formed through a dehydration reaction. Common examples include Sucrose (table sugar), Maltose, and Lactose.

Polysaccharides

Complex carbohydrates made of hundreds to thousands of monosaccharide units. They serve as storage molecules (e.g., starch in plants, glycogen in animals) or structural compounds (e.g., cellulose in plant cell walls).

Lipids

A diverse group of hydrophobic molecules that do not consist of polymers. They include fats (triglycerides) for long-term energy storage, phospholipids for membrane structure, and steroids (like cholesterol and sex hormones) for signaling.

Phospholipid

A molecule with a glycerol backbone, two fatty acid tails (hydrophobic), and a phosphate group head (hydrophilic). This amphipathic nature causes them to assemble into bilayers, forming the fundamental structure of all cell membranes.

Proteins

Highly versatile macromolecules consisting of one or more polypeptide chains folded into a specific three-dimensional shape. They perform essential tasks including catalysis (enzymes), structural support, transport, and immune defense.

Amino Acids

The monomers of proteins, consisting of a central carbon bonded to an amino group ($-NH_{2}$), a carboxyl group ($-COOH$), a hydrogen atom, and a unique side chain (R group) that defines the chemical identity of the amino acid.

Peptide Bond

A specific type of covalent bond that links the carboxyl group of one amino acid to the amino group of the next amino acid during protein synthesis, resulting in the formation of a polypeptide chain.

Nucleic Acids

Polymers called polynucleotides that store, transmit, and help express hereditary information. The two main types are DNA (deoxyribonucleic acid), which provides the genetic blueprint, and RNA (ribonucleic acid), which facilitates protein synthesis.

Nucleotide

The structural subunit of nucleic acids, consisting of three components: a nitrogenous base (Adenine, Guanine, Cytosine, Thymine, or Uracil), a five-carbon pentose sugar (ribose or deoxyribose), and one or more phosphate groups.

Cis Fatty Acids

Unsaturated fatty acids where the hydrogen atoms are located on the same side of the carbon-carbon double bond ($C=C$). This arrangement creates a 'kink' in the fatty acid chain, typically making them liquid at room temperature.

Trans Fatty Acids

Unsaturated fatty acids where the hydrogen atoms are on opposite sides of the double bond. This results in a straight chain similar to saturated fats, making them more likely to be solid at room temperature and associated with increased health risks.

Denaturation

The loss of a protein's native three-dimensional structure due to the disruption of chemical bonds (like hydrogen or ionic bonds) by factors such as extreme heat, pH changes, or high salt concentrations, leading to a loss of biological function.

Quaternary Structure

The level of protein organization that arises when two or more individual polypeptide chains (subunits) aggregate into one functional macromolecule. Examples include hemoglobin, which consists of four subunits.

Primary Structure

The specific, linear sequence of amino acids in a polypeptide chain. This sequence is determined by genetic information and dictates how the protein will eventually fold into its higher-order structures.

Secondary Structure

The localized folding or coiling of the polypeptide backbone caused by hydrogen bonding between non-adjacent amino acids. Common forms include the $\alpha$-helix (coil) and the $\beta$-pleated sheet (folds).

Tertiary Structure

The overall three-dimensional shape of a single polypeptide chain, stabilized by various interactions between R groups (side chains), including hydrophobic interactions, van der Waals forces, ionic bonds, and strong disulfide bridges.

Sugar-Phosphate Backbone

The structural 'rails' of nucleic acids formed by alternating pentose sugar and phosphate groups. These are linked by phosphodiester bonds and provide a directional orientation (5' to 3') for the genetic material.