Human Anatomy and Physiology: Chemical Building Blocks of Life

Comprehensive practice flashcards covering introductory chemical concepts, elements, atomic structure, chemical bonds, reactions, inorganic compounds, and biological macromolecules in human anatomy and physiology.

How many base pairs are contained in human DNA?

There are approximately $3$ billion base pairs in human DNA.

What is the difference between an object's mass and its weight?

An object's mass is the amount of matter contained within it and remains constant regardless of location, whereas its weight is its mass affected by the pull of gravity.

How many fundamental elements exist in the natural world?

All matter in the natural world is composed of one or more of the $92$ fundamental elements.

What are the four most abundant elements in the human body?

Oxygen ($O$), carbon ($C$), hydrogen ($H$), and nitrogen ($N$).

What is the mass of an electron relative to a proton or neutron?

An electron has approximately $\frac{1}{2000}$th the mass of a proton or neutron.

What is the difference between an element's atomic number and its mass number?

The atomic number is the number of protons in the atom's nucleus, while the mass number is the sum of the number of protons and neutrons in its nucleus.

Which naturally occurring element has the most mass, and what are its atomic and mass numbers?

Uranium ($U$), which has an atomic number of $92$ ($92$ protons) and a mass number of $238$ ($146$ neutrons).

What is the half-life of tritium, a radioisotope of hydrogen?

The half-life of tritium is approximately $12 formulation years$.

What principle governs the electron capacity and stability of an atom's valence shell?

The octet rule states that an atom (except hydrogen and helium) will give up, gain, or share electrons so that it ends up with $8$ electrons in its valence shell.

What is the distinction between a cation and an anion?

A cation is a positively charged ion that has donated one or more electrons, while an anion is a negatively charged ion that has accepted one or more electrons.

How do nonpolar covalent bonds differ from polar covalent bonds?

Nonpolar covalent bonds share electrons equally so that no region is more positive or negative, whereas polar covalent bonds share electrons unequally, creating partial positive and partial negative charges.

What is a hydrogen bond?

A hydrogen bond is an attraction formed when a weakly positive hydrogen atom already bound in a polar molecule is attracted to another electronegative atom from another molecule.

What is the difference between exergonic and endergonic chemical reactions?

Exergonic reactions release more energy than they absorb, whereas endergonic reactions absorb more energy than they release.

What are the general equations for synthesis, decomposition, and exchange reactions?

Synthesis: $A + B \rightarrow AB$; Decomposition: $AB \rightarrow A + B$; Exchange: $A + BC \rightarrow AB + C$.

How do enzymes increase the rate of chemical reactions in the body?

Enzymes act as catalysts that lower the activation energy—the threshold level of energy needed to break chemical bonds in the reactants.

What distinguishes an organic compound from an inorganic compound?

An organic compound is a substance that contains both carbon and hydrogen, whereas an inorganic compound does not contain both carbon and hydrogen.

What percentage of an adult human's body weight is composed of water?

Water makes up as much as $70\,\%$ of an adult's body weight.

What is the average blood glucose concentration in a healthy adult, and how many particles are in one mole of a substance?

Average blood glucose concentration is about $100\,mg/dL$, and one mole of any substance contains Avogadro's number of particles: $6.02 \times 10^{23}$.

How do dehydration synthesis and hydrolysis reactions differ?

Dehydration synthesis links monomers together by releasing a molecule of water ($H_2O$), while hydrolysis breaks down polymers into monomers by consuming and splitting a molecule of water.

What defines a chemical salt?

A salt is a substance that, when dissolved in water, dissociates into ions other than $H^+$ or $OH^-$.

What is the normal pH range of human blood, and what conditions describe deviations from this range?

Normal blood pH ranges from $7.35$ to $7.45$. Acidosis occurs when fluid pH drops below $7.35$, and alkalosis occurs when fluid pH rises above $7.45$.

What are the five functional groups important in human physiology?

The hydroxyl, carboxyl, amino, methyl, and phosphate groups.

What are the three hexose monosaccharides important in human biology?

Glucose, fructose, and galactose, each of which contains $6$ carbon atoms.

What structural difference distinguishes saturated fatty acids from unsaturated fatty acids?

Saturated fatty acids have no double carbon bonds along their hydrocarbon chain and hold maximum hydrogen, while unsaturated fatty acids contain one or more double carbon bonds that create kinks.

What is the structural foundation of a steroid compound?

A set of $4$ hydrocarbon rings bonded to a variety of other atoms and molecules.

What four structural groups are bonded to the central carbon atom of an amino acid?

A hydrogen atom, an alkaline amino group ($-NH_2$), an acidic carboxyl group ($-COOH$), and a variable side chain ($R$-group).

What are the four levels of protein structure?

Primary (amino acid sequence), secondary (alpha-helix or beta-pleated sheet), tertiary ($3D$ folding shape), and quaternary (association of two or more polypeptide subunits).

What three subunits make up a nucleotide?

One or more phosphate groups, a pentose sugar (deoxyribose or ribose), and a nitrogen-containing base.

Which nitrogen-containing bases are classified as purines and which as pyrimidines?

Purines (double-ring structure) are adenine and guanine; pyrimidines (single-ring structure) are cytosine, thymine (DNA only), and uracil (RNA only).

What reaction occurs when ATP is hydrolyzed to yield energy in a cell?

Cleavage of a phosphate group converts adenosine triphosphate ($ATP$) into adenosine diphosphate ($ADP$) and inorganic phosphate ($P_i$), liberating stored energy.