Chapter 3 Cell Biology Flashcards

A complete set of vocabulary flashcards covering cell biology basics, microscopy, membrane components, transport methods, organelles, nuclear structures, protein synthesis, and the cell cycle based on Chapter 3 lecture notes.

Cytology

The scientific discipline through which cells, the basic unit of all living things, are studied.

Micrometer

The unit of measurement used for cells, equivalent to $1/10,000\,cm$.

Light Microscope (LM)

An instrument that produces a two-dimensional image by passing light through a specimen, using glass lenses to focus and enlarge the image.

Electron Microscope (EM)

An instrument that uses a beam of electrons to illuminate a specimen, providing greater magnification and resolution than a light microscope.

Transmission Electron Microscope (TEM)

A type of electron microscope that directs an electron beam through thin cut sections to produce two-dimensional images.

Scanning Electron Microscope (SEM)

A type of electron microscope that directs an electron beam across the surface of a specimen to generate a three-dimensional study.

Plasma Membrane

The outer limiting barrier that separates the internal contents of a cell from the external environment.

Nucleus

The largest structure in the cell, acting as the control center, enclosed by a nuclear envelope, and containing genetic material ($DNA$).

Cytoplasm

The cellular contents located between the plasma membrane and the nucleus, consisting of cytosol, organelles, and inclusions.

Cytosol

The viscous, intracellular fluid of the cytoplasm characterized by high water content and containing dissolved macromolecules and ions.

Phospholipid Bilayer

The basic structure of the plasma membrane, composed of two layers of phospholipids with polar heads and hydrophobic tails, ensuring the separation of cytosol and interstitial fluid.

Interstitial Fluid

The fluid that surrounds cells externally.

Cholesterol

A lipid scattered within the phospholipid bilayer that strengthens and stabilizes the membrane against temperature extremes.

Glycolipids

Lipids with attached carbohydrate groups located on the outer phospholipid region that help form the glycocalyx.

Glycocalyx

The "coating of sugar" on the cell's surface formed by glycolipids and glycoproteins, facilitating cell communication and recognition.

Passive Transport

A process that does not require energy and depends on substances moving down a concentration gradient from an area of high concentration to low concentration.

Active Transport

A process that requires energy (usually from $ATP$) to move a substance against its concentration gradient.

Diffusion

The net movement of a substance from an area of greater concentration to an area of lesser concentration due to the kinetic energy of molecules and ions.

Simple Diffusion

A passive process where small, nonpolar molecules move unassisted between phospholipid molecules, including respiratory gases ($O_2$ and $CO_2$), ethanol, and urea.

Facilitated Diffusion

A transport process for small charged or polar solutes that requires assistance from plasma membrane proteins.

Channel-Mediated Diffusion

The movement of small ions through water-filled protein channels that are specific for one ion type.

Carrier-Mediated Diffusion

The movement of small polar molecules across the membrane assisted by a specific carrier protein that changes shape upon binding.

Uniporter

A carrier protein that transports only one type of substance.

Transport Maximum

The maximum rate of substance transport across a membrane, determined by the total number of channels and carriers.

Osmosis

The passive movement of water through a selectively permeable membrane from an area of higher water concentration to an area of lower water concentration.

Aquaporins

Specific integral protein water channels that facilitate the movement of water across the plasma membrane.

Permeable Solutes

Substances that can pass through the phospholipid bilayer, such as oxygen, carbon dioxide, and urea.

Non-Permeable Solutes

Substances prevented from passing through the phospholipid bilayer, including ions, glucose, and proteins.

Isotonic Solution

A solution where the cytosol and the external fluid have the same relative concentration of solutes, such as $0.9\%\,NaCl$ for erythrocytes.

Hypotonic Solution

A solution with a lower concentration of solutes than the cytosol, which may cause water to enter the cell and lead to lysis (rupture).

Hypertonic Solution

A solution with a higher concentration of solutes than the cytosol, which may cause water to leave the cell and lead to crenation (shrinking).

Sodium-Potassium ($Na^+/K^+$) Pump

A type of exchange pump that moves $3\,Na^+$ out of the cell and $2\,K^+$ into the cell against their respective concentration gradients.

Phagocytosis

A form of active transport (cellular eating) where a cell engulfs a large particle by forming extensions called pseudopodia.

Pinocytosis

A form of active transport (cellular drinking) where a cell internalizes droplets of interstitial fluid by forming multiple small vesicles.

Exocytosis

The process by which a cell releases the contents of a secretory vesicle into the interstitial fluid.

Ligand-Receptor Signaling

Communication between cells where molecules (ligands) bind to surface receptors to control grow, reproduction, and other cellular processes.

Endoplasmic Reticulum (ER)

An extensive interconnected membrane network serving as a transport system within the cell.

Rough ER

A region of the endoplasmic reticulum with attached ribosomes, responsible for synthesizing and transporting proteins.

Smooth ER

A region of the endoplasmic reticulum without ribosomes, involved in lipid synthesis, carbohydrate metabolism, and detoxification.

Golgi Apparatus

The "warehouse" of the cell, composed of cisternae, which modifies, packages, and sorts proteins into secretory vesicles or lysosomes.

Lysosomes

Small membranous sacs containing digestive enzymes used to break down endocytosed vesicles or damaged organelles (autophagy).

Peroxisomes

Vesicles pinched off from the rough ER that contain enzymes for the chemical digestion of hydrogen peroxide and the beta oxidation of fatty acids.

Mitochondria

The double-membrane "powerhouses" of the cell that perform aerobic cellular respiration to produce $ATP$.

Ribosomes

Non-membrane-bound organelles containing protein and $RNA$ that function as the sites for protein synthesis.

Cytoskeleton

A network of microfilaments, intermediate filaments, and microtubules that provide structural support, organization, and a track for movement within the cell.

Cilia

Hairlike projections containing microtubules that move substances along the surface of the cell.

Flagella

Long, hairlike projections used to propel an entire cell, such as a sperm cell.

Microvilli

Extensions of the plasma membrane supported by actin microfilaments that increase the surface area of the cell.

Centrosome

A structure located near the nucleus containing a pair of cylindrical centrioles, responsible for organizing microtubules and forming the mitotic spindle during cell division.

Nucleolus

A dark-staining spherical body within the nucleus that produces ribosomes and $RNA$.

Chromatin

The form of genetic material consisting of finely filamented mass of $DNA$ and proteins when the cell is not dividing.

Chromosomes

The tightly coiled mass of $DNA$ observed during cell division.

Genes

Stretches of nucleotides within $DNA$ that provide the instructions for the synthesis of specific proteins.

Transcription

The process by which an $RNA$ polymerase forms an $RNA$ copy of a gene from $DNA$ within the nucleus.

Translation

The synthesis of a new protein where the code in the nucleotide sequence of $mRNA$ is converted into amino acids at the ribosomes.

Codons

Linear sequences of three nucleotide bases in $mRNA$ that code for specific amino acids or signals (start/stop) during translation.

Mitosis

Cell division occurring in somatic cells resulting in two identical daughter cells with the diploid number of chromosomes ($46$ or $2n$).

Meiosis

Cell division in sex cells resulting in cells with the haploid number of chromosomes ($23$ or $n$).

Interphase

The long phase of the cell cycle where the cell carries out normal metabolic activities and prepares for division, consisting of $G1$, $S$, and $G2$ phases.

DNA Polymerase

The enzyme responsible for assembling new strands of $DNA$ during the $S$ phase of interphase by pairing complementary deoxyribonucleotides.

Prophase

The first stage of mitosis where chromatin supercoils into chromosomes, the nucleolus breaks down, and spindle fibers grow from centrioles.

Metaphase

The second stage of mitosis where spindle fibers attach to the centromere of each chromosome and align them on the equatorial plate.

Anaphase

The third stage of mitosis where spindle fibers move sister chromatids apart toward opposite poles of the cell.

Telophase

The final stage of mitosis where chromosomes uncoil back into chromatin, new nucleoli form, and a new nuclear envelope develops around each set of chromosomes.

Cytokinesis

The division of the cytoplasm between two new daughter cells, involving the formation of a cleavage furrow by microfilament proteins.

Apoptosis

The process of programmed cell death or "cellular suicide."

Cellular Differentiation

The process by which unspecialized cells develop into specialized cells with unique functions and characteristics.