Chapter 3: Cell Structure and Function - Vocabulary Flashcards

Key vocabulary terms from Chapter 3 notes on cell structure and function.

Prokaryote

Organisms lacking a membrane-bound nucleus; DNA is free-floating in a nucleoid region; includes bacteria and archaea.

Eukaryote

Organisms with a true nucleus and membrane-bound organelles; includes plants and animals.

Cell theory

All living organisms are composed of cells; new cells arise from pre-existing cells; cells are the basic units of structure and function.

Surface area to volume ratio

Smaller cells have a higher SA:V, enabling more efficient exchange of nutrients and wastes across the cell membrane.

Plasma membrane

The phospholipid bilayer surrounding cells; regulates movement of substances into and out of the cell.

Nucleus

Membrane-bound organelle that houses DNA and controls cellular activities.

Nucleolus

Region within the nucleus where ribosomal subunits are assembled.

Ribosome

Molecular complex that synthesizes proteins by translating mRNA; present in all cells.

DNA

Deoxyribonucleic acid; genetic material stored in the nucleus of eukaryotes or the nucleoid region in prokaryotes.

Endomembrane system

Interconnected membranes (nucleus, ER, Golgi, vesicles, plasma membrane) coordinating synthesis, modification, and transport of proteins and lipids.

Rough endoplasmic reticulum (RER)

ER region studded with ribosomes; synthesizes and processes proteins destined for secretion or membranes.

Smooth endoplasmic reticulum (SER)

ER region lacking ribosomes; synthesizes lipids and participates in carbohydrate metabolism and detoxification.

Golgi apparatus

Stack of flattened sacs that modifies, sorts, and packages proteins and lipids for secretion or delivery to destinations.

Vesicle

Small membrane-bound sac that transports materials between organelles or to/from the cell surface.

Mitochondrion

Organelle producing ATP via cellular respiration; contains its own DNA and ribosomes; double membrane.

Chloroplast

Plant and some protist organelle that conducts photosynthesis; contains chlorophyll and its own DNA and ribosomes; double membrane.

Photosynthesis

Process converting light energy, CO2, and H2O into carbohydrates (glucose) and O2 in chloroplasts.

Cellular respiration

Process converting carbohydrates and O2 into CO2, water, and ATP; occurs in mitochondria of cells.

ATP

Adenosine triphosphate, the cell’s main energy currency produced during cellular respiration.

Plant cell vs. animal cell

Plant cells have cell walls, chloroplasts, and a central vacuole; animal cells lack cell walls and chloroplasts and have centrioles; both have plasma membranes and nuclei.

Cell wall

Rigid layer outside the plasma membrane in plants and many bacteria/fungi; provides structure and protection; not present in animal cells.

Central vacuole

Large plant cell organelle that stores water and maintains turgor pressure.

Cytoskeleton

Network of protein filaments that supports cell shape, organization, and movement of organelles.

Actin filaments

Filaments that support cell shape, enable muscle contraction with myosin, and form microvilli in intestinal cells.

Intermediate filaments

Filaments providing mechanical support, nuclear envelope integrity, and cell-cell junctions; contribute to hair structure.

Microtubules

Hollow tubules made of tubulin; support cell shape, organize organelles, form the spindle during division, and build cilia/flagella.

Centrioles

Animal-cell structures that organize microtubule assembly during cell division.

Cilia and flagella

Hair-like projections; flagella (long) propel, e.g., sperm; cilia line airways and sweep particles; composed of microtubules.

Endosymbiotic theory

Idea that mitochondria and chloroplasts originated as free-living bacteria engulfed by a host cell and became organelles.

Evidence for endosymbiosis

Mitochondria and chloroplasts have double membranes, own circular DNA, ribosomes similar to bacteria, and replicate by splitting.

Archaea relation to eukaryotes

Biochemical data suggest archaea are more closely related to eukaryotes than to bacteria.

Evolution of eukaryotic cells

Fossil record suggests prokaryotes preceded eukaryotes; eukaryotes evolved in stages from prokaryotes; endosymbiosis contributed mitochondria and chloroplasts.

Chromatin

Thread-like form of DNA and associated proteins inside the nucleus; becomes visible as chromosomes during division.

Central dogma (DNA → RNA → protein)

Genetic information flows from DNA to RNA by transcription and from RNA to protein by translation.