Biology: Cells, Organelles, and Transport (Vocabulary Flashcards)

Vocabulary-style flashcards covering cell theory, organelles, and transport mechanisms.

Cell theory

All living things are composed of cells; cells are the basic unit of structure; new cells are produced from existing ones.

Cell membrane

The phospholipid bilayer that encloses the cell, supports a fluid mosaic structure, and is selectively permeable.

Cholesterol (in the cell membrane)

Molecule that provides flexibility and stability to the cell membrane.

Simple diffusion

Movement of small nonpolar molecules from high to low concentration without energy.

Facilitated diffusion

Passive diffusion that uses membrane proteins to aid the movement of substances down a concentration gradient.

Aquaporin

Protein channel that facilitates water diffusion across the cell membrane.

Osmosis

Diffusion of water across a selectively permeable membrane.

Hypertonic

Solutions cause cells to shrink as water moves out of the cell.

Hypotonic

Solutions cause cells to swell as water moves into the cell.

Isotonic

Solutions that cause water to move in and out at a roughly equal rate, keeping cell volume stable.

Endocytosis

Process of bringing materials into the cell via vesicles.

Exocytosis

Process of releasing materials from the cell via vesicles.

Phagocytosis

Engulfing of solid particles (food or debris) by the cell.

Pinocytosis

Engulfing of liquids by the cell.

Receptor-mediated endocytosis

Endocytosis triggered when molecules bind to cell-surface receptors.

Passive transport

Movement of substances across membranes without using cellular energy.

Active transport

Movement of substances against their concentration gradient, requiring energy.

Endosymbiotic theory

Idea that some organelles (mitochondria, chloroplasts) originated from free-living prokaryotes that entered into a symbiotic relationship with early eukaryotic cells.

Margulis

Scientist who proposed and supported the endosymbiotic theory.

Chloroplast

Organelle where photosynthesis occurs; double-membraned, contains chlorophyll, has own DNA, and thylakoid membranes.

Chlorophyll

Green pigment in chloroplasts that captures light for photosynthesis.

Photosynthesis

Process by which chloroplasts capture solar energy and convert it to chemical energy stored in food.

Mitochondria

Organelle that converts energy stored in food into usable cellular energy (ATP); double-membraned with folded inner membrane.

Cellular respiration

Process by which cells convert nutrients into ATP energy.

Double membrane

Two membranes surrounding certain organelles (e.g., mitochondria and chloroplasts).

Inner membrane (cristae)

Folded inner membrane of mitochondria that increases surface area for energy production.

Cristae

Folds of the inner mitochondrial membrane that enhance ATP production.

Thylakoid

Flattened sac inside chloroplasts where light-dependent reactions occur; organized into grana.

Granum

A stack of thylakoids within a chloroplast.

Nucleus

Control center of the cell; contains DNA; surrounded by the nuclear envelope with pores; site of ribosome assembly.

Nucleolus

Dense region inside the nucleus where ribosomal RNA is synthesized and ribosomes begin to assemble.

Nuclear envelope

Double membrane surrounding the nucleus that regulates traffic to and from the nucleus.

Nuclear pores

Channels in the nuclear envelope that regulate movement of RNA and proteins between the nucleus and cytoplasm.

Chromatin

DNA associated with proteins in the nucleus; condenses to form chromosomes during cell division.

Chromosomes

Condensed DNA-protein structures that carry genetic information; visible during cell division.

Ribosome

Molecular machine that synthesizes proteins; can be free-floating or attached to the rough ER.

Rough endoplasmic reticulum (RER)

ER with ribosomes on its surface; synthesizes and packages proteins for export.

Smooth endoplasmic reticulum (SER)

ER lacking ribosomes; synthesizes lipids/carbohydrates and detoxifies chemicals.

Golgi apparatus

Modifies, sorts, and ships proteins and lipids from the ER; forms vesicles for transport.

Vesicle

Small membrane-bound sac that stores and transports substances within the cell.

Lysosome

Organelle containing enzymes that digest and recycle cellular waste and foreign material.

Peroxisome

Organelle that breaks down fatty acids and detoxifies harmful substances.

Cytoskeleton

Network of protein filaments (microfilaments, intermediate filaments, microtubules) that gives the cell shape and enables movement.

Microfilaments

Thin, actin filaments involved in cell movement and shape changes.

Microtubules

Hollow tubes that maintain cell shape and guide organelle movement.

Intermediate filaments

Filaments providing mechanical support and resilience to cells.

Centriole

Structure in animal cells that organizes spindle fibers during cell division.

Spindle fibers

Fibers that separate chromosomes during mitosis and meiosis.

Plasmodesmata

Small channels through plant cell walls that connect adjacent plant cells’ cytoplasm.

Cilium (cilia)

Hair-like projections that move substances along the cell surface or help move the cell.

Central vacuole

Large plant cell vacuole that stores water, ions, and wastes and helps maintain turgor pressure.

Chloroplast DNA

Circular DNA found in chloroplasts, supporting endosymbiotic origins (information in notes).