Cells

Vocabulary practice flashcards covering cellular biology concepts including organelle functions, plasma membrane structure, cell division, and cell cycle regulation.

Cell

The basic unit of life responsible for protection, support, movement, communication, cell metabolism, energy release, and inheritance.

Differentiated Cells

Cells with specialized characteristics that perform specific functional roles in the body.

Plasma Membrane

A flexible, sturdy barrier that surrounds and contains the cytoplasm of a cell, forming the outermost limit that separates the cytosol from extracellular fluid.

Fluid Mosaic Model

A structural model describing the plasma membrane as a sea of lipids containing a mosaic of embedded proteins.

Lipid Bilayer

Two back-to-back layers of lipid molecules self-assembled so that hydrophilic heads form intra- and extracellular surfaces and hydrophobic tails make up the middle portion.

Integral Proteins

Membrane proteins that extend into or across the entire lipid bilayer among the fatty acid tails of phospholipid molecules.

Transmembrane Protein

A type of integral protein that extends through both sides of the lipid bilayer.

Peripheral Proteins

Membrane proteins found at the inner or outer surface of the membrane that associate with one side of the bilayer and can be stripped away without disturbing membrane integrity.

Ion Channel

An integral membrane protein forming a passageway or water-filled pore that allows specific ions to move across the plasma membrane.

Transporter Proteins

Integral membrane proteins that bind a specific substance, change shape, and move the substance across the membrane.

Receptor Proteins

Integral membrane proteins that serve as cellular recognition sites by binding specific substances (such as hormones) to alter cell function.

Linker Proteins

Integral or peripheral membrane proteins that anchor filaments inside and outside the plasma membrane, providing structural stability, maintaining cell shape, and supporting cell movement.

Cell Identity Marker

A glycoprotein (such as Major Histocompatibility Complex proteins) that enables a cell to recognize other similar cells and distinguish self from non-self.

Cellular Adhesion Molecules (CAMs)

Proteins that guide cell movement and facilitate cell adhesion.

Microvilli

Non-motile extensions of the plasma membrane, built of actin filaments, that function to increase cell surface area.

Cilia

Microscopic, hairlike extensions on the exposed surfaces of most cells (such as in the lungs) that move substances across the cell surface.

Flagella

Long, motile processes extending from the surface of sperm cells that aid in locomotion.

Inclusions

Inert chemicals present within the cytoplasm of a cell.

Ribosomes

Structures composed of RNA and proteins scattered in the cytoplasm or bound to the rough endoplasmic reticulum that serve as the site of translation and protein synthesis.

Rough Endoplasmic Reticulum

A membranous network studded with attached ribosomes where proteins are produced and modified.

Smooth Endoplasmic Reticulum

A membranous network lacking attached ribosomes that synthesizes lipids and fatty acids.

Golgi Apparatus

An organelle composed of a stack of 3 to 8 membranous sacs called cisternae that modifies, packages, and distributes proteins and lipids for secretion or internal use.

Lysosomes

Membranous vesicles containing digestive enzymes that serve as the garbage disposals of the cell.

Autophagy

The process of self-digestion where lysosomes break down and recycle worn-out organelles and cellular debris.

Peroxisomes

Membranous structures smaller than lysosomes that contain enzymes to break down fatty acids and amino acids, generating hydrogen peroxide as a by-product.

Proteasomes

Large protein complexes containing enzymes that break down and recycle unneeded or damaged proteins in the cell.

Mitochondria

Double-membraned organelles that serve as the major site of ATP synthesis and contain their own DNA.

Cytoskeleton

An internal framework composed of microtubules, microfilaments, and intermediate filaments that maintains cell shape, aids movement, and assists in cell division.

Nucleus

The innermost principal part of the cell enclosed by the nuclear envelope, containing DNA that directs cellular functions.

Nucleolus

A small structure within the nucleus containing RNA and proteins that serves as the site of ribosome production.

Chromatin

A complex of DNA and protein in the nucleus that makes up the cell's 46 chromosomes.

Centromere

The constricted structure on a chromosome that physically attaches one sister chromatid to another.

Interphase

The stage of the cell life cycle between cell divisions, divided into $G_1$, S, and $G_2$ phases, where the cell grows and replicates its DNA.

$G_0$ Phase

A specialized non-dividing phase entered during the $G_1$ stage by cells that will never divide again.

Mitosis

A series of nuclear division events (prophase, metaphase, anaphase, telophase) leading to the production of two genetically identical daughter cells.

Cytokinesis

The division of the cell cytoplasm following nuclear division.

Apoptosis

Genetically programmed cell death triggered either internally or externally via suicide genes.

Necrosis

Pathological cell death resulting from injury or damage.

Maturation Promoting Factor (MPF)

A protein complex that induces cell division.

Meiosis

Reproductive cell division consisting of two successive stages (Meiosis I and Meiosis II) that yields four haploid gametes containing 23 chromosomes each.