Ch 5: The Structure and Function of Large Biological Molecules

Flashcards covering the structure and function of large biological molecules, including macromolecules, enzymes, carbohydrates, lipids, proteins, and nucleic acids, based on lecture notes.

Macromolecules

Large in size, chain-like molecules called polymers.

Polymers

A long molecule consisting of many similar or identical building blocks linked by covalent bonds.

Monomers

The repeating units ('building blocks') that make up a polymer.

Enzymes

Specialized macromolecules (often proteins) that speed up chemical reactions.

Substrates

The monomers and polymers that react with enzymes.

Condensation reaction

The reaction that connects a monomer to another monomer/polymer, where two molecules are covalently bonded to each other with the loss of a small molecule.

Dehydration reaction

A type of condensation reaction where a water molecule is lost to form a covalent bond and synthesize polymers like carbohydrates and proteins.

Hydrolysis

The opposite of a dehydration reaction, where the addition of a water molecule breaks the bond between monomers.

Carbohydrates

Sugars and polymers of sugars that serve as fuel and building blocks.

Monosaccharides

'Simple sugars' that are the monomers from which more complex carbohydrates are built.

Disaccharides

'Double sugars' formed by two monosaccharides joined by a covalent bond.

Polysaccharides

Carbohydrate macromolecules/polymers composed of many sugar building blocks.

Glucose

A common monosaccharide with the formula C6H12O6, central to life processes, possessing a carbonyl group and multiple hydroxyl groups.

Aldose

A monosaccharide containing an aldehyde carbonyl group.

Ketose

A monosaccharide containing a ketone carbonyl group.

Glycosidic linkage

A covalent bond formed between two monosaccharides by a dehydration reaction, joining them into a disaccharide or polysaccharide.

Starch

A storage polysaccharide in plants, stored as granules within cellular structures like plastids, providing surplus glucose.

Glycogen

A storage polysaccharide in animals, a polymer of glucose stored in liver and muscle cells, providing glucose when energy demand increases.

Cellulose

A major structural polysaccharide component of plant cell walls, a polymer of glucose with 1-4 glycosidic linkages, difficult for most animals to digest.

Chitin

A structural polysaccharide used by arthropods to build exoskeletons and by fungi for cell walls, similar to cellulose in structure.

Lipids

A diverse group of hydrophobic molecules that mix poorly or not at all with water, mostly consisting of hydrocarbons.

Hydrophobic

Water-fearing; describes substances that do not mix well with water.

Fat

A lipid assembled from a glycerol molecule joined to three fatty acids via dehydration reactions.

Glycerol

An alcohol molecule that forms part of a fat, to which fatty acids are attached.

Fatty acid

A long carbon skeleton (hydrocarbon chain) with a carboxyl group at one end, forming part of a fat.

Saturated fatty acid

A fatty acid with no C=C bonds, where each carbon in the skeleton is bonded to as many hydrogens as possible.

Unsaturated fatty acid

A fatty acid that has one or more C=C bonds.

Trans fat

Unsaturated fats with trans double bonds, which can contribute to cardiovascular disease.

Phospholipids

Lipids with two fatty acids attached to a glycerol and a third hydroxyl group joined to a phosphate group, forming cell membranes.

Amphipathic

Having both hydrophilic (polar head) and hydrophobic (nonpolar tails) regions, characteristic of phospholipids.

Steroids

Lipids characterized by a carbon skeleton consisting of four fused rings.

Cholesterol

A steroid that is a component of animal cell membranes and a precursor to other steroids.

Proteins

Biologically functional molecules made up of one or more polypeptides, each folded and coiled into a specific 3D shape, performing diverse functions in living beings.

Amino acids

The monomers of proteins, each possessing both an amino group and a carboxyl group, along with a unique side chain (R group).

Peptide bonds

Covalent bonds that link amino acids together in a polypeptide, formed by a dehydration reaction between the carboxyl group of one amino acid and the amino group of another.

Polypeptide

A polymer of amino acids linked by peptide bonds.

Primary structure (protein)

The unique sequence of amino acids in a polypeptide chain.

Secondary structure (protein)

Regions of a polypeptide stabilized by hydrogen bonds between atoms of the polypeptide backbone, often forming alpha helices or beta pleated sheets.

Alpha helix

A delicate coil in a protein's secondary structure held together by hydrogen bonds between every fourth amino acid.

Beta pleated sheet

A protein's secondary structure where two or more polypeptide chains lie side by side, connected by hydrogen bonds between parallel segments.

Tertiary structure (protein)

The overall 3D shape of a polypeptide, stabilized by interactions between side chains (R groups), including hydrophobic interactions, Van der Waals interactions, hydrogen bonds, ionic bonds, and disulfide bridges.

Disulfide bridges

Covalent bonds that form between the sulfhydryl groups of two cysteine amino acid monomers, helping to stabilize tertiary and quaternary protein structure.

Quaternary structure (protein)

The overall protein structure resulting from the aggregation of two or more polypeptide subunits, not present in all proteins.

Denaturation

When a protein loses its weak chemical bonds, causing it to unravel, lose its specific shape, and therefore lose its function, often caused by changes in pH, salt concentration, or temperature.

X-ray crystallography

A method used to determine the 3D structure of a protein by utilizing the diffraction pattern of an X-ray beam by the atoms of a crystallized molecule.

Nucleic acids

Polymers (DNA and RNA) that store, transmit, and express hereditary information.

Genes

Units of hereditary information, consisting of DNA, that determine the amino acid sequence of a polypeptide.

Deoxyribonucleic acid (DNA)

The genetic material that organisms inherit from their parents, providing directions for its own replication, RNA synthesis, and protein synthesis.

Ribonucleic acid (RNA)

A nucleic acid that directs protein synthesis, acting as a messenger (mRNA) to carry genetic information from DNA to the cell's protein synthesis machinery.

Gene expression

The process by which DNA directs RNA synthesis, and through RNA, controls protein synthesis.

Polynucleotides

The polymers that make up nucleic acids.

Nucleotides

The monomers that combine to form polynucleotides; each has a 5-carbon sugar (pentose), a nitrogenous base, and one to three phosphate groups.

Pyrimidine

A type of nitrogenous base with a 6-membered ring of carbon and nitrogen atoms (Cytosine, Thymine, Uracil).

Purines

A larger type of nitrogenous base with a 6-membered ring fused to a 5-membered ring (Adenine, Guanine).

Deoxyribose

The 5-carbon sugar found in DNA nucleotides.

Ribose

The 5-carbon sugar found in RNA nucleotides.

Nucleoside

The part of a nucleotide consisting only of a nitrogenous base covalently attached to a sugar.

Phosphodiester linkage

A covalent bond that joins adjacent nucleotides in a polynucleotide, linking the sugar of one nucleotide to the phosphate group of the next.

Sugar-phosphate backbone

The repeating sugar and phosphate units that form the structural framework of a polynucleotide strand.

Double helix

The characteristic structure of DNA, consisting of two polynucleotide strands that wind around an imaginary axis and are held together by hydrogen bonds between paired bases.

Antiparallel

Describes the orientation of the two sugar-phosphate backbones in a DNA double helix, running in opposite 5' to 3' directions from each other.

Base pairing (DNA)

The specific hydrogen bonding rules in DNA where Adenine (A) pairs with Thymine (T), and Cytosine (C) pairs with Guanine (G).

Base pairing (RNA)

The specific hydrogen bonding rules in RNA where Adenine (A) pairs with Uracil (U).

Genomics

The analysis of large sets of genes or even whole genomes of a species.

Proteomics

The analysis of large sets of proteins, including their sequences and functions.

Bioinformatics

The use of computer software and other computational tools to handle and analyze large sets of biological data, such as genomic and proteomic information.