Molecular Biology

Molecular biology

The study of biological activity at a molecular level, including the structure and function of chemical substances and their interactions in living processes.

Organic compounds

Compounds that contain carbon and are found in living things, excluding carbides, carbonates, oxides of carbon, and cyanides.

Carbohydrates

Abundant organic compounds composed of carbon, hydrogen, and oxygen atoms in a common ratio, primarily functioning as a source of energy and as recognition and structural molecules.

Lipids

Non-polar, hydrophobic molecules that serve as major components of cell membranes, long-term energy storage molecules, and signaling molecules.

Nucleic acids

Genetic material of all cells, composed of nucleotides, and responsible for determining inherited features and protein assembly.

Proteins

Composed of amino acids, proteins are major regulatory molecules involved in catalysis, structural molecules, and cellular signaling.

Monosaccharides

Monomers of carbohydrates, building blocks of disaccharides and polysaccharides, and exist in different 3D configurations.

Fatty acids

Long chains of hydrocarbons, components of certain lipids, and can be saturated or unsaturated.

Amino acids

Monomers of proteins, consisting of a central carbon connected to an amine group, a carboxyl group, and a variable group.

Nucleotides

Monomers of nucleic acids, consisting of a pentose sugar, a phosphate group, and a nitrogenous base.

Anabolic reactions

Metabolic reactions that build up complex molecules from simpler ones, occurring via condensation reactions.

Catabolic reactions

Metabolic reactions that break down complex molecules into simpler ones, occurring via hydrolysis reactions.

Water

A polar molecule with a slight charge difference across its different poles, capable of forming hydrogen bonds and possessing unique thermal, cohesive, adhesive, and solvent properties.

Vitalism

A disproven doctrine that organic molecules could only be synthesized by living systems due to a "vital force" possessed by living things.

Metabolism

The totality of chemical processes that occur within a living organism, involving enzyme-catalyzed reactions that provide energy and synthesize new materials.

Evaporation

The change of water from liquid to vapor, requiring an input of energy and functioning as a cooling mechanism.

Cohesion

The ability of like molecules to stick together, exhibited by water due to its hydrogen bonding.

Adhesion

The ability of dissimilar molecules to stick together, exhibited by water through intermolecular associations with polar and charged molecules.

Universal solvent

Water's ability to dissolve a large number of substances that contain charged particles or electronegative atoms.

Polar attraction

The polar attraction of water molecules weakens intramolecular forces and can cause dissociation of atoms.

Hydrophilic

Substances that freely associate and dissolve in water, including polar molecules and ions.

Hydrophobic

Substances that do not freely associate or dissolve in water, including large, non-polar molecules like fats and oils.

Water soluble

Substances that can dissolve in water, such as sodium chloride, oxygen, glucose, and ionized amino acids.

Water insoluble

Substances that cannot dissolve in water, such as lipids (fats and cholesterol) and carbohydrates.

Disaccharide

Two monosaccharide monomers joined together via a glycosidic linkage.

Polysaccharide

Many monosaccharide monomers joined together via glycosidic linkages.

Cellulose

A structural polysaccharide found in the cell wall of plants, composed of β-glucose subunits.

Starch

An energy storage polysaccharide found in plants, composed of α-glucose subunits.

Glycogen

An energy storage polysaccharide formed in the liver in animals, composed of α-glucose subunits.

Fatty acids

Long hydrocarbon chains found in lipids, can be saturated or unsaturated.

Saturated fatty acids

Fatty acids with no double bonds, linear in structure, and typically solid at room temperature.

Unsaturated fatty acids

Fatty acids with double bonds, bent in structure, and typically liquid at room temperature.

Trans fatty acids

Unsaturated fatty acids with hydrogen atoms on different sides of the carbon double bond, typically solid at room temperature.

Triglycerides

The largest class of lipids, formed by condensation reactions between glycerol and three fatty acids.

LDL

Low density lipoproteins, carry cholesterol from the liver to the rest of the body, raising blood cholesterol levels.

HDL

High density lipoproteins, scavenge excess cholesterol and carry it back to the liver for disposal, lowering blood cholesterol levels.

Atherosclerosis

Hardening and narrowing of arteries due to the accumulation of fat deposits, leading to cardiovascular diseases.

BMI

Body mass index, a measure of relative mass based on weight and height, used to screen for weight problems in sedentary adults.

Amino acids

The building blocks of proteins, comprised of an amine group, a carboxylic acid group, a hydrogen atom, and a variable side chain.

Side chains

Distinct chemical properties of amino acids that cause proteins to fold and function differently.

Polypeptide chain

Long chains of covalently bonded amino acids.

Peptide bond

Covalent bond formed between the amine and carboxylic acid groups of adjacent amino acids.

Dipeptide

Two amino acids joined together by a peptide bond.

Primary structure

The order of amino acids in a polypeptide chain.

Secondary structure

The folding of amino acid sequences into alpha helices, beta-pleated sheets, or random coils.

Tertiary structure

The overall three-dimensional configuration of a protein determined by interactions between variable side chains.

Quaternary structure

The arrangement of multiple polypeptide chains or inorganic prosthetic groups in a protein.

Denaturation

Structural change in a protein that results in the loss of its biological properties.

Gene

A sequence of DNA that encodes a polypeptide sequence.

Transcription

The process of making an mRNA transcript based on a DNA template.

Translation

The process of using the mRNA transcript to link amino acids together and form a polypeptide.

Proteome

The totality of proteins expressed within a cell, tissue, or organism at a certain time.

Enzyme

A globular protein that acts as a biological catalyst by speeding up chemical reactions.

Active site

The region on the surface of an enzyme that binds to the substrate molecule.

Collision frequency

The rate of enzyme-substrate collisions, which can be increased by increasing molecular motion or concentration of particles.

Denaturation

Disruption of the tertiary structure of an enzyme, resulting in loss of activity.

Temperature

A factor that affects enzyme activity by disrupting hydrogen bonds and denaturing the enzyme.

pH

A factor that affects enzyme activity by altering the charge and shape of the enzyme.

Substrate concentration

A factor that affects enzyme activity by increasing the frequency of enzyme-substrate collisions until saturation is reached.

Biotechnology

The use of enzymes in various processes, such as gene splicing.

Gene splicing

The process of combining DNA from different sources to create a new genetic sequence.

Food production

The use of enzymes in the production and refinement of beers and dairy products.

Enzymes

Proteins that catalyze chemical reactions in living organisms.

Textiles

The use of enzymes in the processing of fibers, such as polishing cloth.

Paper production

The use of enzymes to assist in the pulping of wood for paper production.

Lactose

A disaccharide of glucose and galactose that can be broken down by the enzyme lactase.

Lactase

An enzyme that breaks down lactose into glucose and galactose.

Lactose intolerance

A condition where individuals have a decreased ability to digest lactose due to a decrease in lactase production.

Lactose-free milk

Milk that has been treated with lactase enzyme to break down lactose into glucose and galactose.

Transgenic cows

Cows that have been genetically modified to produce lactose-free milk by splicing the lactase gene into their genome.

Nucleic acids

The genetic material of the cell, composed of nucleotide monomers.

Nucleotides

The monomeric units of nucleic acids, consisting of a pentose sugar, phosphate group, and nitrogenous base.

DNA

Deoxyribonucleic acid, a double-stranded molecule that stores the genetic blueprint for cells.

RNA

Ribonucleic acid, a single-stranded molecule that transfers genetic information for decoding.

DNA replication

The process of copying DNA to produce two identical double-stranded DNA molecules.

Semi-conservative replication

The process where each new DNA molecule consists of one original strand and one newly synthesized strand.

Polymerase chain reaction (PCR)

A laboratory technique used to amplify specific sequences of DNA.

Transcription

The process of synthesizing RNA from a DNA template.

Translation

The process of protein synthesis where the genetic information in mRNA is translated into a sequence of amino acids on a polypeptide chain.

Peptide bonds

Covalent bonds that link amino acids together to form polypeptides.

Genetic code

The universal code used by almost every living organism, where the same codons code for the same amino acids.

Recombinant gene transfer

The process of transferring genes between species, often used to produce human insulin in bacteria.

mRNA

Complementary copy of a DNA segment (gene) that can be used to deduce the gene sequence.

DNA

The original code that mRNA is converted back into, using the rules of complementary base pairing.

Polypeptide

A chain of amino acids formed through the translation of mRNA.

Cell respiration

The controlled release of energy from organic compounds to produce ATP.

Anaerobic respiration

The partial breakdown of glucose in the cytosol without the use of oxygen, resulting in a small yield of ATP.

Aerobic respiration

The complete breakdown of glucose in the mitochondria using oxygen, resulting in a larger yield of ATP.

ATP

Adenosine triphosphate, a high-energy molecule that functions as an immediate source of power for cell processes.

Glycolysis

The anaerobic breakdown of glucose into pyruvate, producing a small yield of ATP.

Lactic acid fermentation

The conversion of pyruvate into lactic acid in animals during anaerobic respiration.

Exercise intensity

The level of intensity during exercise, which affects the type of respiration used and the production of lactate.

Photosynthesis

The process by which cells synthesize organic compounds from inorganic molecules in the presence of sunlight.

Chlorophyll

A green pigment found in photosynthetic organisms that absorbs light for photosynthesis.

Absorption spectrum

The wavelengths of light absorbed by pigments such as chlorophyll.

Action spectrum

The overall rate of photosynthesis at each wavelength of light.

Light dependent reactions

The first step of photosynthesis, where light energy is converted into chemical energy (ATP).

Light independent reactions

The second step of photosynthesis, where ATP and hydrogen are used to synthesize organic compounds.

Chromatography

An experimental technique used to separate mixtures, such as photosynthetic pigments.

Law of limiting factors

The rate of a chemical process, such as photosynthesis, is limited by the factor that is nearest its minimum value.