Cell Structure and Function

Vocabulary flashcards covering the discovery of cells, cell theory, prokaryotic and eukaryotic diversity, plasma membrane structure, and organelles of plant and animal cells.

Cell

The smallest unit of matter that can carry on all the processes of life.

Robert Hooke

An English scientist who, in 1665, used a microscope to observe a thin slice of dead cork; he observed "little boxes" resembling monks' living quarters and coined the term cells.

Anton Van Leeuwenhoek

A Dutch microscope maker who was the first to observe living cells in 1674.

Matthias Schleiden

A scientist who concluded in 1838 that ALL plants are made up of cells.

Theodor Schwann

A scientist who concluded in 1839 that ALL animals are made up of cells.

Rudolph Virchow

A scientist who proposed in 1855 that all cells come from preexisting cells, completing the cell theory.

The Cell Theory

A biological theory comprising three tenets: 1. All living things are composed of one or more cells; 2. Cells are the basic units of structure and function in an organism; 3. Cells come only from the reproduction of existing cells.

Surface Area-to-Volume Ratio

The structural relationship that limits cell size, whereby cells prefer a large surface area relative to a small volume.

Prokaryotes

Organisms consisting of generally smaller and simpler cells that lack a nucleus and membrane-bound organelles, possessing free-floating DNA in the cytoplasm; examples include bacteria.

Eukaryotes

Organisms consisting of generally larger and more complex cells that contain a membrane-bound nucleus enclosing their genetic material along with many internal organelles and membranes; examples include plants, animals, fungi, and protists.

Cell Membrane (Plasma Membrane)

A selectively permeable (semi-permeable) lipid bilayer composed mostly of lipids and proteins that regulates the entry of oxygen and nutrients and the exit of carbon dioxide and wastes.

Fluid Mosaic Model

The model describing the cell membrane structure, where the lipid bilayer behaves more like a fluid than a solid and is mosaic in nature due to its composition of phospholipids and diverse proteins.

Cytoplasm

The fluid portion of the cell that suspends organelles and proteins, houses floating ribosomes, and serves as the site where enzymes are produced.

Nucleus

A large organelle situated near the middle of eukaryotic cells that controls most cellular functions and contains chromosomes composed of DNA and proteins.

Nuclear Envelope

A double membrane, also known as the nuclear membrane, that completely surrounds the cell's nucleus.

Nuclear Pores

Small channels or openings scattered across the nuclear envelope.

Nucleolus

A distinct structure found inside the nucleus that is involved in the synthesis (production) of ribosomes.

Rough Endoplasmic Reticulum

A system of interconnecting intracellular membranes covered with ribosomes that is involved in membrane production and antibody production.

Smooth Endoplasmic Reticulum

A system of intracellular membranes lacking ribosomes that functions in the synthesis of lipids and the detoxification of drugs and poisons.

Ribosomes

Non-membrane-bound organelles composed of ribosomal RNA (rRNA) and proteins that assemble proteins and enzymes according to DNA's code; they reside freely floating in the cytoplasm or attached to the rough endoplasmic reticulum.

Mitochondria

Double-membrane organelles that act as the sites of cellular respiration and ATP production, containing cristae, matrix, ribosomes, and their own small single piece of DNA.

Cristae

The long inner-membrane folds found within mitochondria.

Golgi Apparatus

A stack of flat membrane sacs—also termed the Golgi Complex or Golgi Body—responsible for the packaging, sorting, and shipping of cellular materials.

Cis Face (Golgi Apparatus)

The side of the Golgi apparatus situated close to the endoplasmic reticulum.

Trans Face (Golgi Apparatus)

The side of the Golgi apparatus situated away from the endoplasmic reticulum that pinches off vesicles filled with material.

Lysosomes

Double-membrane organelles containing digestive enzymes that perform intracellular digestion by breaking down food particles, worn-out cell parts, and invading viruses or bacteria.

Vacuole

A membrane-bound storage organelle that primarily holds water, enzymes, food, and cellular waste; plant cells contain one large permanent vacuole, whereas animal cells may have small temporary vacuoles.

Cytoskeleton

A network of thin, fibrous protein layers that acts as a scaffold to provide structural support for organelles, maintain cell shape, and assist in organelle movement.

Microtubules

Larger, hollow cytoskeletal protein cylinders made of tubulin that assist organelle movement and make up cilia, flagella, and centrioles.

Microfilaments

Thin cytoskeletal fibers made of the protein actin.

Cilia

Short, hair-like external structures composed of microtubules that assist in cellular movement and, in the animal respiratory tract, help trap dust particles in mucus.

Flagella

Long, whip-like external structures made of microtubules (typically present as only $1$ to $2$ per cell) that facilitate cell propulsion, such as in sperm cells.

Centrioles

Paired, cylindrical cytoplasmic structures made of microtubules that occur exclusively in animal cells to assist during mitosis and meiosis.

Chloroplast

A double-membraned plant and algae organelle containing chlorophyll that serves as the site of photosynthesis, transforming light energy into usable chemical energy stored in food molecules (sugars).

Thylakoid

A single membranous disc within the stacks located inside a chloroplast.

Grana

Stacks of thylakoid discs contained within a chloroplast.

Stroma

The fluid portion found inside a chloroplast surrounding the grana where solar energy is trapped.

Cell Wall

A rigid outermost layer composed of cellulose fibers found in plants, fungi, bacteria, and some protists that protects and supports the cell.