The Cellular Level of Organization - OpenStax Anatomy and Physiology Chapter 3

Vocabulary flashcards covering cell membrane structure, transport, organelles, cytoskeleton, nucleus, DNA and RNA biology, protein synthesis, and cell cycle concepts mentioned in the notes.

Phospholipid bilayer

Double layer of phospholipids forming the cell membrane; amphipathic with hydrophilic heads facing fluids and hydrophobic tails inward.

Amphipathic

Molecule that has both hydrophilic (polar) and hydrophobic (nonpolar) regions.

Hydrophilic head

Polar, water loving region of a phospholipid that faces intracellular and extracellular fluids.

Hydrophobic tail

Nonpolar, water fearing region of a phospholipid that faces the interior of the bilayer.

Glycolipid

Membrane lipid with carbohydrate attached; acts as a surface marker.

Cholesterol

Sterol in the membrane that stiffens the membrane by wedging between fatty acid tails.

Integral membrane protein

Membrane protein that spans the lipid bilayer.

Peripheral membrane protein

Membrane protein bound to one side of the bilayer with a specific cellular function.

Channel protein

A membrane protein that forms a pore allowing ions to pass; can be open or gated.

Carrier protein

Membrane protein that carries solutes across the membrane, often using energy.

Na+/K+ pump

ATPase pump that moves sodium and potassium across the membrane to maintain gradients.

Desmosome

Anchoring junction that holds cells together, found in skin and heart intercalated discs.

Gap junction

Channel that allows ions and small molecules to pass between adjacent cells.

Tight junction

Junction that seals space between cells to prevent paracellular transport.

Endomembrane system

Network of membranes (ER, Golgi, vesicles, lysosomes) that modifies, sorts, and transports proteins and lipids.

Rough endoplasmic reticulum

ER with ribosomes; synthesizes and modifies proteins.

Smooth endoplasmic reticulum

ER without ribosomes; synthesizes lipids.

Golgi apparatus

Organelle that sorts, modifies, and ships products from the ER; the cellular post office.

Lysosome

Organelle containing digestive enzymes; involved in autophagy and autolysis.

Autophagy

Self-digestion of cellular components via lysosomes.

Autolysis

Self-destruction of a cell due to lysosomal enzyme release.

Mitochondrion

Powerhouse of the cell; site of cellular respiration.

Peroxisome

Organelle containing enzymes that detoxify reactive species.

Cytoskeleton

Network of filaments providing structural support and enabling movement.

Microfilament

Smallest cytoskeletal filaments (actin) involved in movement and shape.

Intermediate filament

Medium diameter filaments providing mechanical strength.

Microtubule

Hollow tubes that transport organelles and form spindle apparatus; make cilia and flagella.

Cilium

Hair like projection that moves fluids across cell surfaces.

Flagellum

Whip like projection enabling cell movement (as in sperm).

Nucleus

Largest organelle; control center containing genetic material.

Nuclear envelope

Double membrane surrounding the nucleus with nuclear pores for transport.

Nuclear pores

Protein channels regulating exchange of materials between nucleus and cytoplasm.

Nucleolus

Region within nucleus where ribosomal RNA is synthesized.

Chromatin

DNA wrapped around histone proteins; condenses to form chromosomes during division.

Histone

Protein around which DNA winds to form nucleosomes.

Nucleosome

DNA-histone unit; basic unit of chromatin structure.

Chromosome

Condensed DNA-protein structure visible during cell division.

DNA

Double stranded molecule storing genetic information; sugar-phosphate backbone.

RNA

Ribonucleic acid; single stranded; uses uracil instead of thymine.

Adenine

Purine base that pairs with thymine in DNA.

Thymine

Pyrimidine base that pairs with adenine in DNA.

Cytosine

Pyrimidine base that pairs with guanine in DNA.

Guanine

Purine base that pairs with cytosine in DNA.

Transcription

Process of copying DNA into messenger RNA.

Translation

Process of converting mRNA sequence into a polypeptide chain (protein).

mRNA

Messenger RNA; carries genetic code from DNA to ribosomes.

tRNA

Transfer RNA; brings amino acids to ribosomes to build proteins.

rRNA

Ribosomal RNA; forms ribosomes and helps read mRNA during translation.

Ribosome

Molecular machine that synthesizes proteins using mRNA templates.

Codon

Three-base sequence on mRNA that codes for one amino acid.

Anticodon

Three-base sequence on tRNA that pairs with a specific mRNA codon.

DNA replication

Process by which a cell duplicates its DNA to form two identical genomes.

Interphase

Phase where the cell grows and copies DNA; not actively dividing.

Mitosis

Division of the nucleus resulting in two genetically identical nuclei.

Cytokinesis

Division of the cytoplasm, producing two separate daughter cells.

Sister chromatids

Two identical copies of a chromosome held together at the centromere after replication.

Prophase

First mitotic phase; chromatids condense, nuclear envelope breaks down.

Metaphase

Chromatids align at the cell equator before separation.

Anaphase

Chromatids are pulled apart to opposite poles of the cell.

Telophase

New nuclei form around chromosomes; spindle breaks down.

Checkpoint（cell cycle）

Gates that stop or proceed with division based on cellular conditions.

Isotonic

Solution with the same solute concentration as the cell, causing no net water movement.

Hypertonic

Solution with higher solute concentration than the cell, water moves out.

Hypotonic

Solution with lower solute concentration than the cell, water moves in.

Diffusion

Movement of solutes from an area of high concentration to low concentration.

Facilitated diffusion

Passive transport where substances cross the membrane via carrier channels when they cannot pass lipid bilayer alone.

Osmosis

Diffusion of water across a semipermeable membrane.

Filtration

Movement of water and solutes through a membrane due to pressure differences.

Semipermeable membrane

Membrane that allows certain substances to pass while restricting others.