Biology: The Cell: The Fundamental Unit of Life

A set of vocabulary flashcards based on key concepts from the lecture on cells in biology.

Prokaryotic Cells

Small, simple cells without organelles, first appearing 3.5 billion years ago and mostly unicellular.

Eukaryotic Cells

Larger, more complex cells with membrane-enclosed organelles, first appearing 2.1 billion years ago and can be unicellular or multicellular.

Chloroplasts

Organelles that convert light energy into food energy through photosynthesis, found in plant cells.

Mitochondria

Organelles involved in cellular respiration that harvest energy from food molecules in both plant and animal cells.

Lysosomes

Membrane-enclosed vesicles containing digestive enzymes that break down and recycle cellular substances.

Endocytosis

The import of substances into the cell by fusing a portion of the cell membrane.

Exocytosis

The export of substances from the cell by vesicles fusing with the plasma membrane.

Nucleus

The organelle that contains most of the cell's DNA and directs cell activities.

Ribosomes

Sites of protein manufacture in the cell; they can be free-floating or attached to the rough endoplasmic reticulum.

Cytoskeleton

A network of protein fibers that maintains the cell's shape, provides support, and aids in movement.

Passive Transport

Movement of substances across a cell membrane without the use of energy, following the concentration gradient.

Active Transport

Movement of substances against a concentration gradient that requires energy.

Plasma Membrane

The outer boundary of the cell that regulates the movement of substances into and out of the cell.

Diffusion

The movement of molecules from an area of higher concentration to an area of lower concentration.

Osmosis

The diffusion of water across a selectively permeable membrane.

Facilitated Diffusion

Process by which large molecules move across a cell membrane via embedded proteins without energy.

Chromatin

DNA molecules wrapped around proteins forming fibers that condense to form chromosomes.

Extracellular Matrix

A sticky substance produced by animal cells that helps hold the cells together, forming tissues.

Cell Wall

A rigid protective layer found in plant and fungal cells that helps maintain cell shape.

Vacuoles

Intracellular sacs used for storage of substances, maintaining the overall health of the cell.