Human Biology, Chemistry, Cells, and Energy Review

Vocabulary review flashcards covering key terms and definitions from Chapters 1, 2, 3, 4, 5, 6, and 14 of Human Biology.

Biology

The study of living things.

Metabolism

The process by which living things assimilate energy and use it to grow, involving the transfer of energy from one form to another.

Homeostasis

The ability of an organism or cell to regulate and maintain stable internal conditions despite changes in the external environment.

Thermoregulation

A negative feedback system that maintains normal body temperature by constricting blood vessels and shivering when temperature falls, or dilating blood vessels and sweating when temperature rises.

Defining Features of Humans

The four specific biological features characteristic of humans: bipedalism, opposable thumbs, a large brain, and the capacity for complex language.

Matter

Anything that has mass and occupies space, existing as a solid, liquid, gas, or plasma.

Element

Pure matter that cannot be broken down into a simpler form, defined by the specific number of protons in its nucleus.

Atom

The smallest possible sample of an element that still retains the physical and chemical properties of that particular element.

Valence Shell

The outermost electron shell of an atom, which determines atomic reactivity and serves as the region where chemical bonding occurs.

Octet Rule

The principle that atoms tend to interact to achieve stability by filling their outermost shell with eight electrons (or two for helium).

Isotope

Atoms of the same element that contain the same number of protons but a different number of neutrons.

Radioisotope

An unstable isotope that emits radiation as it decays.

Covalent Bond

A chemical bond formed when two or more atoms share electrons in their outer valence shell.

Polar Covalent Bond

A covalent bond where shared electrons are pulled closer to the atom with more protons due to greater attraction, producing unequal charge distribution.

Ion

An atom that has lost one or more electrons to become positively charged, or gained one or more electrons to become negatively charged.

Ionic Bond

A chemical bond created by the transfer of electrons, where one atom donates electrons and another accepts them.

Electrolytes

Ions in the body—such as $Ca^{2+}$, $Na^+$, $K^+$, $H^+$, $PO_4^{3-}$, $HCO_3^-$, $Cl^-$, and $OH^-$—that maintain bodily function and homeostasis.

Hydrogen Bond

A weak attraction between the slightly negative end of one polar molecule and the slightly positive end of another polar molecule.

Hydrophilic

Having an affinity for water; water-loving molecules that bond easily with electrical charges.

Hydrophobic

Lacking an affinity for water; water-hating nonpolar molecules.

pH Scale

A measure of the concentration of $H^+$ ions in a solution, where pH values below 7 are acidic ($H^+ > OH^-$) and values above 7 are basic ($OH^- > H^+$).

Buffer

A substance or chemical system that prevents dramatic changes in pH.

Carbohydrates

Biological macromolecule polymers made of saccharides (containing C, H, and O) that provide fuel for the body; includes monosaccharides, disaccharides, and polysaccharides.

Glycogen

The short-term storage polysaccharide in animals, representing approximately $1\text{\%}$ of energy reserves.

Lipids

Water-insoluble organic molecules made of C, H, and O that store long-term energy, protect vital organs, and form cell membranes.

Triglycerides

The storage form of fat in the body composed of glycerol and fatty acids, accounting for $78\text{\%}$ of energy reserves.

Phospholipids

Structural lipid molecules featuring a polar hydrophilic head and two nonpolar hydrophobic tails, serving as the main components of cell membranes.

Proteins

Polymers made of amino acids linked by peptide bonds into polypeptides, forming functional globular structures (enzymes, antibodies) or supportive fibrous structures (keratin, collagen).

Nucleic Acids

Polymers of nucleotides (consisting of a 5-carbon sugar, phosphate group, and nitrogenous base) that comprise DNA for genetic storage and RNA for protein synthesis.

Adenosine Triphosphate (ATP)

The primary short-term energy currency of life, storing reversible and instantly available energy in the bond between its second and third phosphate groups.

Plasma Membrane Structure

A semi-permeable phospholipid bilayer embedded with receptor proteins, channel proteins, gated channels, glycoproteins, carbohydrates, and cholesterol that regulates passage into and out of the cell.

Nucleus

The information center and control center of a eukaryotic cell that contains DNA.

Ribosome

An organelle responsible for protein synthesis.

Rough Endoplasmic Reticulum

Organelle studded with ribosomes that transports and modifies newly synthesized proteins.

Smooth Endoplasmic Reticulum

Organelle lacking ribosomes that synthesizes carbohydrates and lipids (such as fatty acids and hormones), metabolizes alcohol, and performs detoxification.

Golgi Complex

An organelle that puts finishing touches on proteins and lipids, sorting and shipping them via vesicles.

Lysosome

An organelle containing digestive enzymes that breaks down damaged organelles, cellular debris, and foreign material inside the cell.

Peroxisome

A cellular organelle that destroys toxic waste products within the cell.

Mitochondrion

An organelle that breaks down glucose to produce ATP energy for the cell.

Diffusion

Passive transport process moving solutes down a concentration gradient from high to low concentration without requiring energy.

Osmosis

The passive movement of water molecules across a semipermeable membrane from an area of high water concentration to low water concentration.

Tonicity Effects on Red Blood Cells

Changes in cell shape due to osmosis: cells remain normal in isotonic solution ($9\text{ g}$ salt/L), shrivel in hypertonic solution ($18\text{ g}$ salt/L), and swell or burst in hypotonic pure water.

Active Transport

Movement of substances across a cell membrane requiring ATP energy, including protein pumps, endocytosis (outside to inside), and exocytosis (inside to outside).

Anabolism

Metabolic reactions that assemble simple molecules into larger, higher-energy molecules (building up).

Catabolism

Metabolic reactions that break down complex molecules into simpler ones to release energy.

Glycolysis

An anaerobic metabolic pathway occurring in the cell cytoplasm that splits one glucose molecule into two 3-carbon pyruvate molecules, producing a net yield of $2\text{ ATP}$.

Citric Acid Cycle (Krebs Cycle)

An aerobic metabolic pathway in the mitochondria that disassembles pyruvate into Acetyl Co-A, produces $CO_2$, yields $2\text{ ATP}$, and transfers high-energy electrons/$H^+$ to NAD+ and FAD.

Aerobic Cellular Respiration Pathways

The complete metabolic process consisting of Glycolysis ($2\text{ ATP}$), the Krebs Cycle ($2\text{ ATP}$), and the Electron Transport System ($32\text{ ATP}$ to $34\text{ ATP}$) using oxygen to convert glucose into ATP, $CO_2$, and $H_2O$.

Anaerobic Respiration

ATP generation in the absence of oxygen where glycolysis proceeds, but pyruvate is converted to lactic acid because it cannot enter the Citric Acid Cycle, yielding only $2\text{ ATP}$.

Peristalsis

Involuntary wave-like smooth muscle contractions that push food and substances through the gastrointestinal tract.