Hole's Human Anatomy & Physiology: Chapters 3 and 4 Vocabulary

Vocabulary flashcards covering key terms and definitions from Chapters 3 and 4 of Hole's Human Anatomy & Physiology, including cell biology, membrane transport, metabolic processes, cellular respiration, genetic control, and cell division.

Metabolism

The sum of all chemical reactions occurring in the body.

Cellular Metabolism

The sum of all chemical reactions occurring specifically inside a cell.

Anabolism

A metabolic process in which smaller molecules are built into larger ones, requiring ATP energy.

Catabolism

A metabolic process in which larger molecules are broken down into smaller ones, releasing energy.

Dehydration Synthesis

An anabolic reaction where smaller molecules are bound together to form larger molecules, producing $H_2O$ in the process.

Hydrolysis

A catabolic reaction that uses $H_2O$ to split larger molecules into smaller ones; the reverse of dehydration synthesis.

Enzyme

A globular protein catalyst that increases the rate of a chemical reaction by lowering its required activation energy without being consumed.

Denaturation

The inactivation of an enzyme or protein due to an irreversible change in its conformation, preventing it from binding to its substrate.

Metabolome

All small molecules (metabolites) that are part of the metabolism in a cell, tissue, organ, or organism.

Metabolic Pathway

A series of enzyme-controlled chemical reactions leading to the formation of a specific product.

Rate-Limiting Enzyme

A regulatory enzyme present in limited quantities that sets the overall rate for an entire metabolic reaction sequence, typically positioned first in the pathway.

Cofactor

A non-protein substance, such as an ion, element, or small organic molecule, that combines with an enzyme to activate it.

Coenzyme

An organic cofactor molecule, usually derived from essential vitamins, that aids enzyme function.

Phenylketonuria (PKU)

An inborn error of metabolism where a missing or nonfunctional enzyme blocks the conversion of phenylalanine to tyrosine, causing excess phenylalanine to poison the brain.

Cellular Respiration

A metabolic process consisting of glycolysis, the citric acid cycle, and the electron transport chain that transfers energy from molecules like glucose to make ATP available for cellular use.

ATP (Adenosine Triphosphate)

The main energy-carrying molecule in a cell, consisting of adenine, ribose, and three phosphate groups attached by high-energy bonds.

Phosphorylation

The process of attaching a third phosphate group to ADP using energy from cellular respiration to recreate ATP.

Glycolysis

The anaerobic phase of cellular respiration occurring in the cytosol that breaks down a 6-carbon glucose molecule into two 3-carbon pyruvic acid molecules, yielding a net gain of 2 ATP.

Citric Acid Cycle

An aerobic cyclic metabolic pathway in the mitochondria where acetyl CoA combines with oxaloacetic acid to form citric acid, producing 1 ATP, 8 hydrogen transfers to FAD, and 2 $CO_2$ per turn.

Electron Transport Chain (ETC)

A series of enzyme complexes in the inner mitochondrial membrane that transfer high-energy electrons from NADH and FADH2 to ATP synthase, producing 26 to 28 ATP with oxygen as the final electron acceptor.

Genome

The complete set of genetic information in a cell.

Exome

The small portion of the genome that codes directly for functional proteins.

Gene Expression

The control of which proteins are produced in a cell type, in what amounts, and under which specific circumstances.

Complementary Base Pairing

The specific hydrogen bonding between nitrogenous base pairs in nucleic acids, specifically Adenine with Thymine (or Uracil in RNA) and Cytosine with Guanine.

Transcription

The process occurring in the nucleus where RNA polymerase copies a DNA sequence into a complementary messenger RNA (mRNA) sequence.

Translation

The process occurring in the cytoplasm where mRNA genetic codons are decoded by ribosomes and tRNAs to assemble a specific sequence of amino acids into a polypeptide chain.

Codon

A three-base mRNA sequence that specifies a particular amino acid or signals the initiation or termination of protein synthesis.

Anticodon

A three-base nucleotide sequence on a tRNA molecule that binds to a complementary mRNA codon during translation.

Mutation

A change in the DNA base sequence caused spontaneously or induced by exposure to mutagens such as chemicals or radiation.

Differentiated Cells

Cells that have developed specialized structural and functional characteristics.

Cytosol

The fluid portion of the cytoplasm in which cellular organelles are suspended.

Cell Membrane

The selectively permeable outer phospholipid boundary of a cell that regulates the entry and exit of substances and handles signal transduction.

Signal Transduction

The process by which the cell membrane allows a cell to receive, process, and respond to incoming molecular signals.

Cellular Adhesion Molecules (CAMs)

Membrane proteins like selectins and integrins that anchor, guide, and direct moving cells to specific cellular targets.

Ribosome

An organelle composed of rRNA and protein molecules that provides structural support and enzymatic activity to link amino acids during translation.

Endoplasmic Reticulum (ER)

A tubular membrane network in the cytoplasm divided into Rough ER (studded with ribosomes for protein synthesis) and Smooth ER (lacks ribosomes, conducts lipid synthesis).

Golgi Apparatus

A stack of flattened membranous sacs that refines, packages, and delivers proteins synthesized on the rough ER.

Mitochondria

Fluid-filled, membrane-bound organelles known as the powerhouse of the cell that conduct cellular respiration reactions to generate ATP.

Lysosomes

Membranous organelles containing digestive enzymes that break down proteins, carbohydrates, nucleic acids, debris, and worn-out cell parts.

Peroxisomes

Membranous sacs containing enzymes that digest lipids, alcohol, and hydrogen peroxide.

Centrosome

A structure near the nucleus consisting of two centrioles made of microtubules that produce spindle fibers during cell division.

Cilia

Abundant, short, motile extensions of the cell membrane made of microtubules that beat in a coordinated fringe pattern to move fluids across cell surfaces.

Flagellum

A long, single motile extension of the cell membrane, such as a sperm cell tail, that moves an entire cell.

Krabbe Disease

An organelle-level disease caused by the lack of a single lysosomal enzyme, preventing myelin production and damaging the nervous system.

Adrenoleukodystrophy (ALD)

A metabolic disorder caused by a missing protein in peroxisome membranes, leading to fatty acid accumulation that destroys myelin sheaths.

Diffusion

The passive movement of atoms, molecules, or ions from a region of higher concentration to one of lower concentration until equilibrium is reached.

Facilitated Diffusion

Passive transport of water-soluble substances across the cell membrane using membrane-bound ion channels or transporter proteins.

Osmosis

The passive movement of water across a selectively permeable membrane toward a region containing a higher concentration of impermeant solute.

Osmotic Pressure

The force generated by osmosis to lift a volume of water, which increases as impermeant solute concentrations rise.

Isotonic Solution

A solution that has the same osmotic pressure as intracellular fluid, resulting in no net gain or loss of water by the cell.

Hypertonic Solution

A solution with higher osmotic pressure than intracellular fluid, causing cells to lose water and shrink.

Hypotonic Solution

A solution with lower osmotic pressure than intracellular fluid, causing cells to gain water and swell.

Filtration

A passive physical process that forces water and small solute molecules through membranes using hydrostatic or fluid pressure.

Active Transport

The ATP-requiring movement of substances across a cell membrane against their concentration gradient using specific carrier proteins.

Pinocytosis

A form of endocytosis in which a cell membrane indents and engulfs tiny droplets of liquid into a vesicle.

Phagocytosis

A form of endocytosis in which a cell membrane engulfs solid particles such as cellular debris or bacteria.

Receptor-Mediated Endocytosis

A selective form of endocytosis where specific target molecules bind to membrane receptor proteins before being internalized in a vesicle.

Exocytosis

The process by which membrane-bound vesicles fuse with the cell membrane to release their contents outside the cell.

Transcytosis

A process combining receptor-mediated endocytosis and exocytosis to rapidly transport a particle across a cellular barrier.

Interphase

The active phase of the cell cycle comprising $G_1$, $S$ (DNA replication), and $G_2$ phases, during which the cell grows and prepares for division.

Mitosis

The division of the cell nucleus in somatic cells, consisting of prophase, metaphase, anaphase, and telophase.

Cytokinesis

The division of the cytoplasm beginning in anaphase and ending in telophase via a contractile ring of actin filaments.

Telomeres

Repeated DNA sequences at chromosome tips that shorten with each round of mitosis, functioning as a mitotic clock.

Oncogenes

Abnormal or overexpressed versions of regulatory genes that increase the rate of cell division, contributing to cancer.

Tumor Suppressor Genes

Genes that normally limit or inhibit cell division, whose inactivation or deletion permits uncontrolled mitosis and cancer.

Stem Cell

An undifferentiated cell capable of self-renewal or dividing to produce one stem cell and one partially specialized progenitor cell.

Progenitor Cell

A partially specialized, committed daughter cell derived from a stem cell that can divide to form a restricted set of cell types.

Totipotent

Cells (like a fertilized egg or early embryonic cells) capable of developing into any specialized cell type.

Pluripotent

Cells capable of differentiating into a limited number of specialized cell types.

Apoptosis

A continuous, stepwise, programmed pathway of normal cell death.

Necrosis

Disordered cell death resulting from severe tissue damage or injury.