Chapter 5 Structure and Function of Large Biological Molecules

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

Macromolecules

Larger molecules composed of thousands of atoms, weighing over 100,000 daltons, formed by joining smaller organic molecules.

Major Classes of Macromolecules

Carbohydrates, lipids, proteins, and nucleic acids.

Polymers

Chainlike molecules consisting of many similar or identical building blocks linked by covalent bonds.

Monomers

The 'small' repeated units that are building blocks for polymers, linked by covalent bonds.

Dehydration Synthesis (Condensation Reaction)

A process of joining monomers to add polymers by losing a molecule of water via formation of covalent bonds.

Hydrolysis

A process of breaking polymers into monomers by adding a molecule of water, disassembling covalent bonds.

Enzymes

Mostly proteins (tertiary and quaternary structures) that act as catalysts to accelerate or speed up chemical reactions without being permanently changed in the process.

Carbohydrates

Macromolecules with a basic composition of carbon plus water ('hydrated carbon'), important as cellular fuel and structural materials.

Monosaccharides

Simple sugars with molecular formulas that are usually multiples of CH2O and contain multiple hydroxyl groups; classified by the location of the carbonyl group and the number of carbons.

Disaccharides

Carbohydrates consisting of two monosaccharide units joined by a glycosidic linkage.

Oligosaccharides

A few monosaccharides covalently linked.

Polysaccharides

Polymers consisting of chains of monosaccharide or disaccharide units linked by glycosidic bonds, typically thousands of subunits.

Aldose (Aldehyde Sugar)

A monosaccharide classified by having the carbonyl group at the end of the carbon skeleton (an aldehyde group).

Ketose (Ketone Sugar)

A monosaccharide classified by having the carbonyl group within the carbon skeleton (a ketone group).

Glucose

A common hexose monosaccharide (C6H12O6), the monomer of most biological polysaccharides, which can form alpha or beta ring structures.

Glycosidic Linkage (Glycosidic Bond)

A type of covalent bond that joins a carbohydrate molecule to another group, formed between two monosaccharides through a dehydration reaction.

Alpha-Glucose

A form of glucose ring where the hydroxyl group attached to the anomeric carbon is below the plane of the ring.

Beta-Glucose

A form of glucose ring where the hydroxyl group attached to the anomeric carbon is above the plane of the ring.

Starch

A storage polysaccharide in plants, unbranched or branched chains of alpha-glucose, consisting of amylose (linear) and amylopectin (branched).

Amylose

A linear polymer of alpha-glucose units linked primarily by 1,4 links, typically assuming a helical configuration.

Amylopectin

A branched polymer of alpha-glucose units with both 1,4 and 1,6 links, highly branched with branches of approximately 20-25 glucose units.

Glycogen

A highly branched storage polysaccharide in animals, similar to starch, often called animal starch.

Cellulose

The major structural component of plant cell walls, an unbranched polysaccharide made of beta-glucose monomers, indigestible by most animals.

Chitin

A structural polysaccharide, a modified form of cellulose with a nitrogen group added to the glucose units, found in fungal cell walls and arthropod exoskeletons.

Lipids

A diverse group of large biological molecules that do not include true polymers, unified by their hydrophobic nature due to consisting mostly of nonpolar hydrocarbons.

Fats (Triacylglycerols/Triglycerides)

Lipids constructed from a glycerol molecule and three fatty acid molecules joined by ester linkages, primarily functioning in energy storage.

Glycerol

A three-carbon alcohol with a hydroxyl group attached to each carbon, forming part of a fat molecule.

Fatty Acid

A molecule consisting of a carboxyl group attached to a long carbon skeleton, which can be saturated or unsaturated.

Ester Linkage

A covalent bond that joins a fatty acid to glycerol in a fat molecule, formed through a dehydration reaction.

Saturated Fatty Acids

Fatty acids that have the maximum number of hydrogen atoms possible and no double bonds in their carbon chains.

Saturated Fats

Fats made from saturated fatty acids, typically solid at room temperature (e.g., most animal fats).

Unsaturated Fatty Acids

Fatty acids that have one or more double bonds in their carbon chains, often causing kinks.

Unsaturated Fats (Oils)

Fats made from unsaturated fatty acids, typically liquid at room temperature (e.g., plant and fish fats).

Hydrogenation

The process of converting unsaturated fats to saturated fats by adding hydrogen, which can also create trans double bonds.

Trans Fats

Unsaturated fats with trans double bonds, formed during hydrogenation of vegetable oils, that may contribute to cardiovascular disease.

Adipose Cells

Cells in which humans and other mammals store their long-term food reserves as fat, also cushioning vital organs and insulating the body.

Phospholipids

Lipids in which two fatty acids and a phosphate group are attached to glycerol, forming a hydrophilic head and hydrophobic tails.

Phospholipid Bilayer

A double-layered structure formed by phospholipids when added to water, with hydrophobic tails pointing inward and hydrophilic heads facing outward, characteristic of cell membranes.

Steroids

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

Cholesterol

A type of steroid that is a component in animal cell membranes and a precursor from which other steroids (like sex hormones) are synthesized.

Proteins

Biologically functional molecules that consist of one or more polypeptides, instrumental in structural support, storage, transport, signaling, movement, defense, and enzymatic regulation.

Polypeptides

Unbranched polymers built from amino acid monomers, linked by peptide bonds.

Amino Acids

Organic molecules that are the monomers of proteins, each possessing an amino group, a carboxyl group, a hydrogen atom, and a unique side chain (R group) attached to a central alpha carbon.

R groups (Side Chains)

The distinguishing part of an amino acid that varies in composition and determines its physical and chemical properties.

Peptide Bond

A covalent bond that links amino acids together to form polypeptides, formed between the carboxyl group of one amino acid and the amino group of another through a dehydration reaction.

N-terminus (Amino End)

The end of a polypeptide chain with a free amino group.

C-terminus (Carboxyl End)

The end of a polypeptide chain with a free carboxyl group.

Primary Structure (Protein)

The unique linear sequence of amino acids in a polypeptide chain, determined by inherited genetic information.

Secondary Structure (Protein)

Coils (alpha helix) and folds (beta pleated sheet) in the polypeptide chain, resulting from hydrogen bonds between repeating constituents of the polypeptide backbone.

Alpha Helix

A common type of secondary protein structure, a delicate coil held together by hydrogen bonding between every fourth amino acid.

Beta Pleated Sheet

A common type of secondary protein structure, where two or more segments of the polypeptide chain lie side by side and are connected by hydrogen bonds.

Tertiary Structure (Protein)

The overall three-dimensional shape of a polypeptide, resulting from interactions between polypeptide R groups (e.g., hydrogen bonds, ionic bonds, hydrophobic interactions, van der Waals interactions, disulfide bridges).

Disulfide Bridges

Strong covalent bonds formed between the thiol groups of two cysteine monomers, reinforcing the protein's tertiary structure.

Quaternary Structure (Protein)

The overall protein structure that results from the aggregation of two or more polypeptide chains (subunits) into one functional macromolecule.

Denaturation

The loss of a protein’s native three-dimensional structure due to alterations in physical and chemical conditions (e.g., pH, salt concentration, temperature), rendering the protein biologically inactive.

Chaperonins (Chaperone Proteins)

Protein molecules that assist the proper folding of other proteins, creating a hydrophilic environment for polypeptide folding.

Nucleic Acids

Polymers (polynucleotides) that store, transmit, and help express hereditary information, with two types: DNA and RNA.

DNA (Deoxyribonucleic Acid)

The genetic material that organisms inherit from their parents, providing directions for its own replication and directing the synthesis of messenger RNA (mRNA).

RNA (Ribonucleic Acid)

A nucleic acid that plays various roles in gene expression, including carrying genetic instructions from DNA to ribosomes (mRNA) and participating in protein synthesis.

Genes

Units of inheritance consisting of DNA fragments that program the amino acid sequence of polypeptides.

Nucleotides

The monomers of nucleic acids, each consisting of a nitrogenous base, a pentose sugar (ribose or deoxyribose), and one or more phosphate groups.

Nucleoside

The portion of a nucleotide without the phosphate group, composed of a nitrogenous base and a pentose sugar.

Nitrogenous Bases

Components of nucleotides, belonging to two families: pyrimidines (cytosine, thymine, uracil) and purines (adenine, guanine).

Pyrimidines

Nitrogenous bases (cytosine, thymine, and uracil) that have a single six-membered ring structure.

Purines

Nitrogenous bases (adenine and guanine) that have a six-membered ring fused to a five-membered ring structure.

Deoxyribose

The pentose sugar found in DNA, lacking one oxygen atom compared to ribose.

Ribose

The pentose sugar found in RNA, containing a hydroxyl group at the 2' carbon.

Phosphodiester Linkage

The type of covalent bond that holds two nucleotides together, forming the sugar-phosphate backbone of a nucleic acid.

DNA Double Helix

The three-dimensional structure of DNA molecules, consisting of two polynucleotides spiraling around an imaginary axis, running in opposite (antiparallel) 5' to 3' directions.

Antiparallel

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

Base Pairing

The specific hydrogen bonding rules between nitrogenous bases: Adenine (A) always pairs with Thymine (T) in DNA (or Uracil (U) in RNA), and Cytosine (C) always pairs with Guanine (G).

Gene Expression

The process by which information from a gene is used in the synthesis of a functional gene product, such as a protein or RNA.

Central Dogma

The flow of genetic information: DNA to RNA to Protein.

Messenger RNA (mRNA)

An RNA molecule that carries genetic information from DNA in the nucleus to ribosomes in the cytoplasm, where it specifies the amino acid sequence of a polypeptide.

Mutations

Changes in the genetic material of a cell or virus.

Point Mutations

Chemical changes in just one base pair of a gene, which can lead to the production of an abnormal protein.

Sickle-Cell Disease

An inherited blood disorder resulting from a single amino acid substitution (valine replaces glutamic acid) in the protein hemoglobin, an example of a point mutation in DNA sequence.

Bioinformatics

The use of computer software and other computational tools to deal with the large amounts of data resulting from sequencing many genomes and proteins.

Genomics

The analysis of large sets of genes or comparing whole genomes of different species.

Proteomics

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

Molecular Genealogy

Assessing evolutionary relationships between species by comparing sequences of genes and their protein products.