Lesson 2_Ch. 2: The Cellular Level of Organization Flashcards

A comprehensive vocabulary flashcard set covering cytology, cell theory, microscopy, cell shapes, plasma membrane structure, organelles, cell junctions, cytoskeleton elements, cell cycle phases, mitosis, and stem cell biology based on Lesson 2_Ch. 2.

Cytology

The study of cell structure and function.

Cell Theory

The principle stating that: (1) all organisms are composed of cells; (2) the cell is the basic structural and functional unit of life; (3) cells arise from preexisting cells; (4) cells share fundamental biochemical similarities; (5) organismal functions arise from cellular activity; (6) most metabolism occurs within cells.

Magnification

The enlargement of an image.

Resolution

The ability to distinguish two close points as separate, determining image clarity and detail.

Light Microscope (LM)

A microscope that uses visible light to view whole cells and tissues with moderate resolution.

Transmission Electron Microscope (TEM)

A microscope that passes electrons through ultrathin sections to reveal the highest internal detail.

Scanning Electron Microscope (SEM)

A microscope that directs electrons over surfaces to provide 3D-like surface detail.

Squamous

Thin, flat, scale-like cell shape suited for rapid diffusion; found in alveoli, capillary endothelium, and surface epidermis.

Cuboidal

Cell shape where height is approximately equal to width, featuring a central round nucleus; found in kidney tubules and gland ducts.

Columnar

Cell shape taller than wide, with nuclei often basal, and may have microvilli or cilia; found in intestinal lining and uterine tubes.

Polygonal

Irregular, many-sided cell shape found in hepatocytes and many epithelia.

Stellate

Star-shaped cell with multiple processes, typical of neurons.

Spheroidal–ovoid

Round to oval cell shape, characteristic of oocytes and leukocytes.

Discoidal

Disc-shaped (often biconcave) cell shape, characteristic of erythrocytes (RBCs).

Fusiform

Spindle-shaped cell with a thick center and tapered ends, characteristic of smooth muscle.

Fibrous

Long, slender, threadlike cell shape, characteristic of skeletal muscle fibers and long axons.

Intracellular Fluid (ICF)

The cytosol or fluid located inside cells.

Extracellular Fluid (ECF)

Fluids located outside cells, such as interstitial fluid, plasma, and cerebrospinal fluid (CSF).

Apical Surface

The free surface of a polarized cell.

Basal Surface

The surface of a polarized cell attached to the basement membrane.

Lateral Surface

The cell-to-cell side surface of a polarized cell.

Selective Permeability

The property of the plasma membrane that regulates the entry and exit of substances.

Glycocalyx

An external carbohydrate coat formed by glycolipids and glycoproteins used for protection, adhesion, and identity.

Transmembrane Proteins

Membrane proteins that span across the lipid bilayer.

Peripheral Proteins

Membrane proteins that attach to the inner or outer surfaces of the membrane bilayer.

Unit Membrane

The structure consisting of the phospholipid bilayer together with its associated proteins.

Microvilli

Cell-surface extensions that increase surface area for absorption.

Primary Cilia

Non-motile cell extensions that serve sensory functions.

Motile Cilia

Cell-surface extensions containing an axoneme, basal body, and dynein that move fluid across the cell surface.

Flagellum

A long motile appendage responsible for cell movement, found on sperm cells.

Pseudopods

Changing cellular projections used for cell movement and phagocytosis.

Tight Junctions

Cellular junctions that seal cells near the apical surface to prevent leakage between cells (e.g., intestinal epithelium).

Desmosomes

Cellular junctions that act as mechanical anchors to hold cells together (e.g., in the epidermis).

Gap Junctions

Junctions consisting of connexon channels that allow passage of ions and small solutes for electrical and metabolic coupling (e.g., cardiac muscle).

Cytosol

The intracellular fluid containing solutes inside the cytoplasm.

Microfilaments

Cytoskeletal elements made of actin (~6 nm in size) involved in cell shape, support, terminal web structure, and cell contraction.

Intermediate Filaments

Cytoskeletal elements (8–10 nm in size, e.g., keratin) providing tensile strength and junction support.

Microtubules

Dynamic cytoskeletal cylinders (~25 nm in size) made of tubulin arising from the centrosome that serve as tracks, cilia/flagella elements, and the mitotic spindle.

Nucleus

The control center of the cell surrounded by a double envelope with pores, containing chromatin and a nucleolus for rRNA synthesis.

Rough Endoplasmic Reticulum (RER)

A membrane network studded with ribosomes that functions in protein synthesis.

Smooth Endoplasmic Reticulum (SER)

A membrane network lacking ribosomes that functions in lipid and steroid synthesis, as well as detoxification.

Ribosomes

Structures composed of protein and RNA, either free in cytosol or RER-bound, responsible for protein synthesis.

Golgi Apparatus

An organelle that modifies, sorts, and packages proteins into vesicles for secretion or delivery to lysosomes.

Proteasomes

Organelles responsible for degrading tagged proteins.

Lysosomes

Membrane-bound organelles containing hydrolytic enzymes used for autophagy and apoptosis.

Peroxisomes

Organelles that carry out oxidation reactions and contain catalase to break down $H_2O_2$.

Mitochondria

Double-membrane organelles containing cristae, matrix, enzymes, ribosomes, and mtDNA that produce ATP.

Centrosome

An organelle containing a pair of centrioles (microtubule cylinders) that organizes the mitotic spindle and forms basal bodies in ciliated cells.

Inclusions

Nonliving, non-membrane-bound, and nonessential cell components, such as stored products (glycogen, lipids) or foreign matter (dust, bacteria, viral particles).

$G_1$ Phase

First gap phase of interphase characterized by growth and normal cellular tasks.

S Phase

Synthesis phase of interphase during which DNA and centrioles are replicated.

$G_2$ Phase

Second gap phase of interphase focused on final preparation for cell division.

$G_0$ Phase

A quiescent state in which cells exit the active cell cycle.

M Phase

The period of the cell cycle comprising mitosis and cytokinesis.

Tumor (Neoplasm)

An abnormal mass resulting from excessive cell growth.

Malignancy

An invasive and metastatic form of cancer.

Prophase

The first phase of mitosis where chromosomes condense, the nuclear envelope breaks down, and the spindle attaches to kinetochores.

Metaphase

The stage of mitosis where chromosomes align along the cell equator.

Anaphase

The stage of mitosis where sister chromatids separate and move toward opposite poles.

Telophase

The stage of mitosis where new nuclear envelopes form and chromosomes uncoil.

Cytokinesis

The division of the cytoplasm resulting in two distinct cells.

Stem Cell

Immature cells with the ability to develop into one or more types of mature, specialized cells.

Developmental Plasticity

The ability of stem cells to give rise to a diversity of mature cell types.

Unipotent Stem Cells

Adult stem cells that can develop into only one mature cell type.

Multipotent Stem Cells

Adult stem cells that can develop into multiple mature cell types.

Pluripotent Stem Cells

Embryonic stem cells found in human embryos up to 150 cells that have broad potential to develop into any cell type.