RT 2107 Biochemistry in Respiratory Therapy – Units 1-5

What is the primary focus of biochemistry?

The study of chemical substances in living organisms and their interactions, i.e., the chemistry of life at the molecular level.

Name two major goals biochemists seek to achieve.

(1) Describe the structure, organization, and functions of living matter in molecular terms; (2) Explain how organisms obtain energy and transmit information to grow and reproduce.

Which three historical disciplines merged to create modern molecular biology?

Biochemistry, cell biology, and genetics.

Give one example of a disease that clarified biochemical understanding because of its genetic component.

Sickle-cell anemia (also acceptable: atherosclerosis or diabetes mellitus).

What percentage of the human body is water and why is this important?

About 70%; water acts as a universal solvent, has high boiling/low freezing points, and buffers temperature changes.

List the four main classes of biomolecules.

Proteins, carbohydrates, lipids, and nucleic acids.

Differentiate macrominerals from microminerals with one example each.

Macrominerals are required in larger amounts (e.g., Ca²⁺), whereas microminerals are needed in trace amounts (e.g., Zn²⁺).

Define a cell in biochemistry terms.

The smallest living unit capable of growth, metabolism, response to stimuli, and replication, containing organelles composed of macromolecules.

Name the three domains of life.

Archaea, Bacteria (together prokaryotes), and Eukarya.

What is the main genetic structure in a prokaryotic cell called?

The nucleoid (a single circular DNA loop).

Which organelle is known as the cell’s “powerhouse” and why?

The mitochondrion; it oxidizes fuels to produce ATP.

State one primary function of lysosomes.

Break down and remove old cell parts using hydrolytic enzymes (cellular digestion).

What is cell fractionation?

A laboratory method where cells are gently disrupted and centrifuged to isolate organelles for study.

Differentiate autotrophs from heterotrophs.

Autotrophs produce organic compounds from inorganic sources (e.g., plants via photosynthesis); heterotrophs obtain organic carbon by consuming other organisms.

In an oxidation-reduction reaction, what does oxidation involve?

Loss of electrons, gain of oxygen, or loss of hydrogen (increase in oxidation number).

Name the oxidized and reduced forms of NAD.

Oxidized: NAD⁺ ; Reduced: NADH.

Define hydrolysis.

A reaction in which water is split into H⁺ and OH⁻, breaking a bond in the substrate.

What enzyme family catalyzes transamination reactions?

Transaminases.

What is the difference between transamination and deamination?

Transamination transfers an amino group; deamination removes an amino group, often producing ammonia.

Describe a condensation reaction.

Two molecules combine to form one product with the loss of a small molecule, often water.

What pH range is considered physiological for most cells?

Approximately pH 6.7 – 7.4.

Provide the formula for calculating pH.

pH = −log₁₀[H₃O⁺].

What is the ion-product constant of water (Kw) at 25 °C?

1.0 × 10⁻¹⁴.

Define a buffer.

A solution of a weak acid and its conjugate base that resists drastic pH changes when small amounts of acid or base are added.

Name the three main physiological buffer systems.

Phosphate buffer (intracellular), histidine–imidazole buffer, and bicarbonate buffer (blood plasma).

Explain respiratory alkalosis in terms of CO₂ and pH.

Hyperventilation decreases blood CO₂, lowering carbonic acid, decreasing [H⁺], and raising blood pH above normal.

What are proteins chemically?

Polymers of amino acids linked by covalent peptide bonds.

List two elemental components often found in specialized proteins besides C, H, O, and N.

Sulfur (S) and iron (Fe) (others include P or metal ions).

Provide three functional classes of proteins with examples.

Catalytic (e.g., amylase), structural (collagen), transport (hemoglobin).

Define an α-amino acid.

An organic compound where both the amino (-NH₂) and carboxyl (-COOH) groups are attached to the same α-carbon along with a variable R side chain.

How many standard amino acids exist, and on what basis are they commonly classified?

Twenty; classified by R-group polarity (non-polar aliphatic, non-polar aromatic, polar neutral, polar acidic, polar basic).

Differentiate essential from non-essential amino acids.

Essential amino acids cannot be synthesized in adequate amounts by the body and must be obtained from diet; non-essential can be synthesized endogenously.

What is the isoelectric point (pI) of an amino acid?

The pH at which the amino acid has no net electric charge (exists mainly as a zwitterion).

Describe chirality in amino acids.

Except glycine, amino acids have four different groups on the α-carbon, creating D and L enantiomers; naturally occurring proteins use L-forms.

Name the unique covalent bond formed between two cysteine residues.

A disulfide bridge (-S-S-).

Why do phenylalanine, tyrosine, and tryptophan absorb UV light at 280 nm?

Because of their aromatic rings, enabling spectrophotometric detection of proteins.

Define a peptide bond.

An amide linkage between the α-carboxyl of one amino acid and the α-amino of another, releasing water.

What distinguishes primary, secondary, tertiary, and quaternary protein structure?

Primary: amino acid sequence; Secondary: local folding (α-helix, β-sheet); Tertiary: overall 3-D folding of a single chain; Quaternary: spatial arrangement of multiple subunits.

Give one example each of a fibrous and a globular protein.

Fibrous: collagen; Globular: myoglobin.

What is protein denaturation?

Unfolding or disruption of secondary, tertiary, or quaternary structure without breaking peptide bonds, often causing loss of function.

List two