Unit II: Chemistry, Nutrition, and Digestion Vocabulary

This set of vocabulary flashcards covers essential terms from Unit II, including atomic structure, chemical bonding, transport mechanisms, the four major biological macromolecules, cell organelles, and the fundamentals of human nutrition and digestion.

Element

A chemical substance that cannot be broken down into any other substance.

Atom

The smallest unit of an element.

Proton

A subatomic particle that carries a positive charge ($+$).

Neutron

A subatomic particle that carries no charge.

Electron

A subatomic particle that carries a negative charge ($-$) and determines an atom's bonding behavior.

Atomic Mass

The combined mass of the protons and neutrons in the nucleus of an atom.

Radioisotopes

Unstable atoms that spontaneously release high-energy particles as they decay over time.

Half-life

The time it takes for a specific amount of a radioisotope to decrease by half.

Octet Rule

The principle that atoms are most stable and least likely to bond when their outermost electron shell is filled to capacity.

Ion

A charged atom that either has extra electrons (negative charge) or lacks electrons (positive charge) relative to its number of protons.

Molecule

A group of atoms held together by chemical bonds.

Ionic Bond

A bond formed by the electrical attraction between two oppositely charged atoms.

Covalent Bond

A strong bond created by atoms sharing pairs of electrons.

Hydrogen Bond

A weak bond formed between a slightly positive atom in one polar molecule and a slightly negative atom in another.

H+ and OH- ions

The hydrogen and hydroxide ions released when a water molecule is broken apart.

pH Scale

A measurement scale from $0$ to $14$ used to determine how acidic or basic a solution is.

Buffer

A substance that can absorb or release chemicals to keep the pH of a solution stable.

Passive Transport

The movement of molecules across a membrane that does not require the cell to use energy.

Diffusion

The spontaneous movement of a solute from an area of higher concentration to an area of lower concentration.

Osmosis

The specific passive diffusion of water across a membrane.

Active Transport

The movement of molecules across a membrane that requires the use of energy (ATP), often to move substances against their concentration gradient.

Monomers

The small building blocks or base components that are linked together to form polymers.

Dehydration Synthesis

A chemical reaction that creates macromolecules by joining monomers together.

Hydrolysis

A chemical reaction that breaks down macromolecules into smaller units.

Monosaccharides

Simple sugars, such as glucose, that act as the building blocks for carbohydrates.

Starch

A polysaccharide that functions as an energy storage molecule in plants.

Glycogen

A complex carbohydrate that stores energy in humans.

Cellulose

An indigestible polysaccharide found in plant cell walls that provides structural support.

Triglyceride

A type of dietary fat molecule composed of a glycerol head and three hydrocarbon tails.

Hydrogenation

A chemical process that adds hydrogen to unsaturated fats to solidify them, often creating trans fats.

Phospholipid

A dual-natured molecule with a polar hydrophilic head and nonpolar hydrophobic tails that forms the basic structure of the cell membrane.

Amino Acids

The $20$ different building blocks that connect via peptide bonds to form proteins.

Enzymes

Proteins that act as biological catalysts to speed up chemical reactions by lowering the activation energy.

Nucleotides

The building blocks of nucleic acids, each consisting of a phosphate group, a sugar, and a nitrogenous base.

Double-helix

The spiraling ladder-like structure of DNA formed by two strands bound by hydrogen bonds.

Organelles

Specialized compartments within eukaryotic cells, such as mitochondria or lysosomes, that perform specific functions.

Calorie

A unit of energy measurement equivalent to the amount of energy required to raise $1$ gram of water by $1^{\circ}C$.

Amylase

An enzyme in the mouth that begins the physical breakdown of starch molecules.

Peristalsis

The waves of muscle contractions that propel food through the esophagus and into the stomach.

Chyme

The liquefied mixture of food and digestive juices that leaves the stomach for the small intestine.

Peptide

A short chain of amino acids linked by peptide bonds, typically consisting of fewer than 50 amino acids.

Hydrogen Bond

A weak bond formed between a slightly positive atom in one polar molecule and a slightly negative atom in another.

Monomers and Polymers

Monomers are small building blocks that link together to form larger macromolecules (polymers) like carbohydrates, proteins, and nucleic acids.

Dehydration Synthesis

A chemical reaction that creates macromolecules by joining monomers together.

Hydrolysis

A chemical reaction that breaks down macromolecules into smaller units, involving the addition of water.

Types of Carbohydrates

Includes monosaccharides (simple sugars), disaccharides, and polysaccharides, providing insight into carbohydrate molecules.

Types of Amino Acids

The 20 different amino acids that combine to form proteins, each varying in structure and properties.

Enzymes

Proteins that act as biological catalysts, facilitating chemical reactions involving molecules.

Isotope

Variants of a chemical element that differ in neutron number, resulting in different atomic masses.

The Big Four Elements

The four most abundant elements in living organisms: carbon, hydrogen, oxygen, and nitrogen.

Electron Shells

The energy levels around an atom's nucleus where electrons are found, arranged in increasing distance from the nucleus.

Solvency

The ability of a substance to dissolve in a solvent, often used in reference to water as a universal solvent.

Cohesion

The attractive force between molecules of the same substance, contributing to surface tension.

Surface Tension

The tendency of liquid surfaces to shrink to their minimum surface area due to cohesive forces between molecules.

Density

The mass per unit volume of a substance, often influencing its buoyancy in fluids.

Antacids

Substances that neutralize stomach acidity, often used to relieve heartburn and indigestion.

Solutions

Homogeneous mixtures composed of solute(s) dissolved in a solvent.

Tonicity

The ability of a solution to change the shape or tension of cells by altering their internal water content.

Primary Active Transport

The process of moving ions or molecules across a membrane against their concentration gradient using energy (ATP).

Secondary Active Transport

The transport of molecules across a membrane using the energy created by the primary active transport of another molecule.

Primary Function of Complex Carbohydrates

To provide energy storage and structural support in organisms.

Complex Carbohydrates

Polysaccharides made of long chains of monosaccharide units, such as starch and cellulose.

Types of Polysaccharides

Includes starch, glycogen, and cellulose, each serving different functions in organisms.

Triglycerides

A type of fat consisting of glycerol and three fatty acids, used for energy storage.

Saturation Levels of Fats

Refers to the degree of hydrogen saturation in fatty acids: saturated fats have no double bonds, unsaturated fats have one or more double bonds.

Steroids

A class of lipids characterized by a four-ring structure, including hormones like testosterone and cholesterol.

Phospholipids

Molecules that make up the cell membrane, composed of a hydrophilic head and two hydrophobic tails.

Polar

A molecule with an unequal distribution of charge, leading to positive and negative regions.

Nonpolar

A molecule with an even distribution of charge, lacking charged poles.

Bilayer

A double layer of phospholipids that forms the basic structure of cell membranes.

Plasma Membrane Proteins

Proteins embedded in or associated with the plasma membrane that facilitate communication and transport.

Nucleotide

The basic building block of nucleic acids, consisting of a phosphate group, a sugar, and a nitrogenous base.

DNA Structure

Composed of two strands forming a double helix, characterized by uprights (sugar-phosphate backbone) and rungs (base pairs).

Uprights of DNA

The sugar and phosphate components that make up the backbone of the DNA strand.

Rungs of DNA

The pairs of nitrogenous bases (adenine-thymine, cytosine-guanine) that connect the two DNA strands.

Base Pairing Rules

Adenine pairs with thymine, and cytosine pairs with guanine in DNA.

RNA

A single-stranded nucleic acid involved in protein synthesis and genetic information transfer.

Prokaryotic Cells

Unicellular organisms that lack a nucleus and membrane-bound organelles, such as bacteria.

Eukaryotic Cells

Organisms composed of cells that have a nucleus and membrane-bound organelles.

Cytoskeleton

A network of fibers within cells that provides structural support and facilitates cell movement.

Lysosomes

Organelles that contain digestive enzymes for breaking down waste materials and cellular debris.

Rough Endoplasmic Reticulum (RER)

A type of endoplasmic reticulum studded with ribosomes, involved in protein synthesis and modification.

Smooth Endoplasmic Reticulum (SER)

A type of endoplasmic reticulum without ribosomes, involved in lipid synthesis and detoxification.

Golgi Apparatus

An organelle that modifies, sorts, and packages proteins and lipids for secretion or delivery to other organelles.

Central Vacuole

A large organelle found in plant cells that stores nutrients, waste products, and helps maintain turgor pressure.

1 Calorie (cal)

The amount of energy required to raise the temperature of 1 gram of water by 1°C.

1 Kilocalorie (kcal)

Equivalent to 1,000 calories; commonly used to measure the energy content of foods.

Energy Density

The amount of energy (calories) provided per unit of food or substance.

Indigestion

A general term for discomfort in the stomach associated with difficulty in digesting food.

Pathway of Digestion

The sequence of organs through which food passes from ingestion to elimination: mouth, esophagus, stomach, small intestine, large intestine.

Food Label Calculations

Processes to determine nutritional values and serving sizes based on the information provided on food packaging.