Biological Molecules, Enzymes, and Cell Transport

Comprehensive vocabulary flashcards covering biological molecules (carbohydrates, lipids, proteins, nucleic acids), vitamins, minerals, enzyme kinetics, biotechnology, and cellular transport mechanisms.

Tissue

A group of similar cells having the same shape and function, such as bone, muscle, or nerve tissue.

Organ

A structure composed of several different tissues working together to carry out a special function, such as the heart, lungs, or brain.

Organ System

A group of organs whose functions are closely related, such as the circulatory system or nervous system.

Metabolic Reactions

The collective set of chemical reactions occurring continuously in the body that involve the formation and breakdown of molecules.

Condensation Reaction

A combination reaction that involves the joining of molecules (such as monomers forming a polymer) accompanied by the release of water.

Hydrolysis Reaction

A decomposition reaction that involves the splitting of molecules (such as a polymer into monomers) through the addition of water.

Glycosidic Bond

The covalent chemical bond that forms between sugar molecules during carbohydrate synthesis.

Monosaccharide

A simple carbohydrate unit formed by $1$ single sugar molecule, such as glucose, fructose, or galactose, which is soluble in water and sweet in taste.

Disaccharide

A carbohydrate formed by $2$ sugar molecules combined together by a glycosidic bond, including maltose, lactose, and sucrose.

Polysaccharide

A complex carbohydrate polymer formed by more than $9$ sugar units bonded together, which is typically insoluble in water and not sweet in taste.

Maltose

A disaccharide formed when $2$ molecules of glucose are joined together by a glycosidic bond.

Sucrose

A disaccharide transported in plants that is composed of $1$ molecule of glucose and $1$ molecule of fructose linked by a glycosidic bond.

Lactose

The disaccharide found in milk, composed of $1$ molecule of glucose and $1$ molecule of galactose linked together by a glycosidic bond.

Starch

A water-insoluble storage polysaccharide used by plant cells to store carbohydrates.

Glycogen

The storage polysaccharide used by animal cells to store carbohydrates.

Cellulose

A structural polysaccharide found in the cell walls of plant cells that provides structural support.

Benedict's Test

A biochemical test for reducing sugars where heating with Benedict's reagent above $80^\top\text{C}$ changes color from blue to green, yellow-brown, or brick red as sugar concentration increases.

Iodine Test

A test for the presence of starch using dilute iodine dissolved in potassium iodide; the triiodide anion ($\text{I}_3^-$) complexes with starch to yield an intense blue-black color.

Triglyceride

A lipid molecule composed of $1$ molecule of glycerol linked to $3$ fatty acid molecules via ester bonds.

Ethanol Emulsion Test

A qualitative test for lipids where the food sample is dissolved in $5\,\text{cm}^3$ of ethanol and poured into water; the formation of a cloudy white emulsion indicates the presence of lipids.

Peptide Bond

The chemical covalent bond that links amino acid monomer subunits together to form protein polypeptide chains.

Protein Denaturation

The irreversible loss of a protein's three-dimensional structure and function caused by the breakdown of cross-linkages at temperatures above $50^\circ\text{C}$ or extreme pH.

Biuret Test

A chemical test used to detect the presence of proteins, yielding a violet or purple color as a positive result.

Nucleotide

The monomer building block of nucleic acids, consisting of a simple sugar (ribose or deoxyribose), a phosphate group, and a nitrogenous base.

Messenger RNA (mRNA)

A single-stranded nucleic acid that copies the DNA code and carries the genetic information from the nucleus to ribosomes in the cytoplasm for protein synthesis.

Transfer RNA (tRNA)

A type of RNA that translates the sequence of mRNA nucleic acids into the correct sequence of amino acids during protein synthesis.

Ribosomal RNA (rRNA)

A type of RNA that joins amino acids held by tRNA via peptide bonding to build polypeptide chains.

Scurvy

A nutritional deficiency disease caused by a lack of vitamin C, characterized by bleeding from the teeth and gums.

DCPIP Test

A test for vitamin C in which the addition of vitamin C causes the blue color of DCPIP solution to decolorize and turn colorless.

Rickets

A disease in young children characterized by soft bones, caused by a dietary deficiency of vitamin D or calcium.

Biological Catalyst

A substance, such as an enzyme, that speeds up chemical reactions inside living cells without being consumed or permanently altered in the process.

Substrate

The specific molecule on which an enzyme acts during a chemical reaction.

Active Site

The specific region of an enzyme molecule, consisting of a binding site and a catalytic site, into which a complementary substrate binds.

Enzyme-Substrate Complex

The temporary intermediate formed when a substrate molecule binds to the complementary active site of an enzyme.

Intracellular Enzymes

Enzymes that are produced inside cells and remain within the cell to catalyze reactions in the cytoplasm and nucleus.

Extracellular Enzymes

Enzymes synthesized inside cells and subsequently secreted to perform catalytic functions outside of the cell.

Optimum Temperature

The temperature at which an enzyme operates with maximum catalytic activity, which is $40^\circ\text{C}$ for most human enzymes.

Optimum pH

The specific pH level at which an enzyme works best, such as pH $2$ for stomach pepsin and pH $7$ for salivary amylase.

Pectinase

An enzyme used in the fruit juice industry to catalyze the hydrolysis of pectin, facilitating juice extraction from fruits.

Lactase

An enzyme used in the dairy industry to digest and break down lactose, producing lactose-free milk for lactose-intolerant individuals.

Cellulase

An industrial enzyme that hydrolyzes cellulose into simple sugars suitable for fermentation into biofuel.

Catalase

An intracellular enzyme abundant in liver tissue that catalyzes the decomposition of toxic hydrogen peroxide into water and oxygen gas.

Passive Transport

A mechanism of cellular transport in which molecules or ions move down a concentration gradient across the cell membrane without the expenditure of cellular energy.