Organelles/cell types

Cell

The basic structural and functional unit of every organism.

Structures found in all cells

Every cell has a plasma membrane, cytosol, chromosomes, and ribosomes.

Prokaryotic cell

A generally small cell without a nucleus or other membrane-bound organelles; bacteria and archaea are prokaryotes.

Eukaryotic cell

A cell with DNA inside a nucleus and many membrane-bound organelles; animals, plants, fungi, and protists are eukaryotes.

Organelle

A specialized structure inside a cell that performs a particular function.

Compartmentalization

The separation of cellular reactions into different organelles; prevents interfering reactions and increases membrane surface area for reactions.

Endomembrane system

A group of connected or interacting membranes including the nuclear envelope, ER, Golgi apparatus, lysosomes, vesicles, vacuoles, and plasma membrane.

Energy organelles

Mitochondria and chloroplasts; organelles that transform energy and contain their own DNA and ribosomes.

Plasma membrane

A selectively permeable boundary that surrounds every cell and controls what enters and leaves.

Cytosol

The fluid portion of the cytoplasm where many chemical reactions occur.

Cytoplasm

Everything between the plasma membrane and nucleus, including the cytosol and suspended organelles.

Chromosome

A DNA molecule containing genetic information; located in the nucleus of eukaryotes and nucleoid of prokaryotes.

Nucleus

Stores the chromosomes and protects the genetic information of a eukaryotic cell.

Nuclear envelope

A double membrane that surrounds the nucleus and separates its contents from the cytoplasm.

Nuclear pores

Openings in the nuclear envelope that regulate movement of RNA, proteins, and ribosomal subunits into and out of the nucleus.

Nucleolus

A dense region inside the nucleus where ribosomal RNA is produced and ribosomal subunits begin assembling.

Ribosomal RNA (rRNA)

RNA that combines with proteins to form the large and small subunits of ribosomes.

Messenger RNA (mRNA)

An RNA copy of genetic instructions that carries information from DNA to a ribosome.

Ribosome

A structure made of rRNA and proteins that performs translation and builds polypeptides.

Translation

The process in which a ribosome reads mRNA and joins amino acids into a polypeptide.

Free ribosome

A ribosome suspended in the cytosol; usually produces proteins that function inside the cytosol.

Bound ribosome

A ribosome attached to the rough ER or nuclear envelope; usually produces proteins for secretion, membranes, or the endomembrane system.

Endoplasmic reticulum (ER)

A network of membrane sacs and tubes that synthesizes membranes and separates cellular reactions.

Rough ER

Ribosome-covered ER that produces and begins processing proteins that will be secreted or placed in membranes.

Smooth ER

ER without ribosomes that synthesizes lipids, metabolizes carbohydrates, stores calcium, and detoxifies chemicals.

Golgi apparatus

Stacks of flattened membrane sacs that modify, sort, and package proteins and lipids.

Cisternae

The separate flattened membrane sacs that form the Golgi apparatus.

Cis face of the Golgi

The receiving side of the Golgi that accepts transport vesicles from the ER.

Trans face of the Golgi

The shipping side of the Golgi that sends packaged materials to other locations or the plasma membrane.

Transport vesicle

A small membrane sac that carries proteins and other materials between organelles.

Secretory vesicle

A vesicle that fuses with the plasma membrane to release proteins or insert membrane proteins.

Exocytosis

The release of materials when a vesicle fuses with the plasma membrane.

Secreted protein pathway

A protein is made by a ribosome on the rough ER, packaged in a vesicle, modified by the Golgi, placed in a secretory vesicle, and released through exocytosis.

Lysosome

An enzyme-filled membrane sac that digests macromolecules, food, pathogens, and damaged cell parts.

Hydrolytic enzyme

An enzyme inside a lysosome that uses water to break large molecules into smaller components.

Autophagy

The process in which lysosomes digest and recycle damaged organelles or other parts of their own cell.

Peroxisome

A membrane-bound organelle that breaks down fatty acids and detoxifies harmful substances; especially important in liver cells.

Vesicle

A small membrane-bound sac that stores, transports, or secretes materials.

Vacuole

A membrane-bound sac that stores food, water, nutrients, or waste.

Central vacuole

A large plant-cell vacuole that stores water and nutrients and helps maintain turgor pressure.

Turgor pressure

Pressure created when water in the central vacuole pushes against the cell wall and keeps a plant firm.

Endosymbiotic theory

The theory that mitochondria and chloroplasts developed from free-living prokaryotes engulfed by an early eukaryotic cell.

Evidence for endosymbiotic theory

Mitochondria and chloroplasts have double membranes, circular DNA, bacterial-like ribosomes, and the ability to reproduce partly independently.

Mitochondrion

The organelle that performs aerobic cellular respiration and produces most of a eukaryotic cell’s ATP.

Outer mitochondrial membrane

The smooth outer boundary of a mitochondrion.

Inner mitochondrial membrane

The folded mitochondrial membrane containing the electron transport chain and ATP synthase.

Cristae

Folds of the inner mitochondrial membrane that increase surface area for ATP production.

Intermembrane space

The region between the inner and outer mitochondrial membranes where hydrogen ions accumulate during cellular respiration.

Mitochondrial matrix

The space enclosed by the inner membrane; contains enzymes for the Krebs cycle, mitochondrial DNA, and ribosomes.

Krebs cycle location

The Krebs cycle occurs in the mitochondrial matrix.

Electron transport chain location

The electron transport chain of cellular respiration is located in the inner mitochondrial membrane.

ATP synthesis location

Most ATP from aerobic respiration is produced by ATP synthase in the inner mitochondrial membrane.

Metabolic activity and mitochondria

Cells with high energy demands, such as contracting muscle cells, normally contain more mitochondria.

Chloroplast

An organelle in plants and other photosynthetic eukaryotes that performs photosynthesis.

Chlorophyll

The green pigment in chloroplasts that absorbs light energy.

Thylakoid

A flattened membrane sac inside a chloroplast where the light-dependent reactions occur.

Granum

A stack of thylakoids that provides additional membrane surface area for light-dependent reactions.

Stroma

The fluid surrounding the thylakoids; contains enzymes for the Calvin cycle, chloroplast DNA, and ribosomes.

Light-dependent reactions location

These photosynthetic reactions occur in the thylakoid membranes and transform light energy into chemical energy.

Calvin cycle location

The Calvin cycle occurs in the stroma and uses carbon dioxide to help build sugars.

Main mitochondrion versus chloroplast difference

Mitochondria release usable energy from food through cellular respiration, while chloroplasts capture light energy to produce sugars through photosynthesis.

Cytoskeleton

A network of protein fibers that supports the cell, anchors organelles, transports materials, and allows movement.

Motor protein

A protein that uses ATP to carry vesicles or other materials along cytoskeletal fibers.

Microtubule

A hollow cytoskeletal rod made of tubulin; supports the cell, transports organelles, separates chromosomes, and forms cilia and flagella.

Tubulin

The protein subunit from which microtubules are constructed.

Centrosome

The region where microtubules are organized and assembled in animal cells.

Centriole

A cylindrical structure inside many animal-cell centrosomes that helps organize microtubules during cell division.

Microfilament

A thin solid cytoskeletal fiber made of actin; maintains shape and assists with movement, muscle contraction, and cell division.

Actin

The protein that forms microfilaments and works with myosin during movement and contraction.

Myosin

A motor protein that interacts with actin to produce contraction and movement.

Cleavage furrow

The indentation formed by an actin-based contractile ring as an animal cell divides.

Intermediate filament

A durable cytoskeletal fiber that maintains cell shape and anchors the nucleus and other organelles.

Nuclear lamina

A layer of intermediate filaments lining the nuclear envelope and supporting the nucleus.

Cilia

Numerous short projections made from microtubules that move a cell or move material across its surface.

Flagellum

A long projection used for movement in some cells; eukaryotic flagella are built from microtubules.

Pseudopod

A temporary actin-supported extension used by cells such as amoebas for movement or engulfing material.

Microvilli

Small actin-supported projections that increase a cell’s surface area for absorption.

Cell wall

A rigid extracellular layer that provides support, protection, and shape.

Plant cell wall

A cell wall made primarily from the polysaccharide cellulose.

Fungal cell wall

A cell wall made primarily from the polysaccharide chitin.

Bacterial cell wall

A cell wall made primarily from peptidoglycan.

Plasmodesmata

Channels through plant cell walls that allow neighboring plant cells to exchange materials and communicate.

Extracellular matrix (ECM)

A network of proteins outside animal cells that provides support and helps cells attach to one another.

Collagen

A major protein in the extracellular matrix that gives tissues strength.

Gap junction

A channel connecting neighboring animal cells and allowing small substances or signals to pass directly between them.

Tight junction

A connection that seals neighboring animal cells and prevents substances from leaking between them.

Nucleoid

The non-membrane-bound region of a prokaryotic cell containing its main chromosome.

Plasmid

A small circular piece of prokaryotic DNA that replicates separately from the main chromosome.

Pili

Short projections used by some prokaryotes for attachment or DNA transfer.

Capsule

A sticky protective coating around some prokaryotes that helps prevent drying and assists attachment.

Photoautotroph

An organism that uses light energy to produce organic molecules from carbon dioxide; plants are photoautotrophs.

Chemoheterotroph

An organism that obtains both energy and carbon by consuming organic molecules; animals are chemoheterotrophs.

If the nucleolus becomes defective

The cell will make fewer ribosomal subunits, reducing its ability to produce proteins.

If the rough ER becomes defective

The cell will have difficulty producing and processing secreted and membrane proteins.

If the Golgi apparatus becomes defective

Proteins may not be correctly modified, sorted, packaged, or delivered.

If lysosomes become defective

Waste and damaged cell components may accumulate because the cell cannot digest or recycle them properly.

If smooth ER or peroxisomes become defective

The cell may have difficulty detoxifying chemicals and breaking down lipids.

If mitochondrial cristae decrease

The cell will have less inner-membrane surface area and may produce less ATP.

If thylakoid membranes become damaged

The light-dependent reactions and production of chemical energy for the Calvin cycle will decrease.

If microtubules become defective

Chromosome separation, organelle transport, cilia movement, and flagellar movement may be disrupted.