Cell Structure and Function

Vocabulary

capsule

a polysaccharide layer tightly adhered to the outside of the cell wall that prevents cell dehydration and helps the cell to stick to surfaces

cell membrane

the structure that encloses the cell, made of the phospholipid bilayer

cell wall

a rigid carbohydrate structure that provides overall support and protection for the cell

centrosome

a structure in the cytoplasm of animal cells that coordinates the formation of microtubules, which allow cell division to proceed during reproduction

chloroplast

a membrane-bound organelle found in plants and some other organisms that captures energy from light and converts it into chemical energy

chromosome

a structure that contains DNA, the genetic material that is passed from one generation to the next

cytoplasm

a combination of cytosol, a jellylike fluid primarily made up of water and dissolved substances that fill the spaces around the internal cell structures, and organelles (excluding the nucleus)

cytoskeleton

a network of filaments that gives the cell its shape and forms the support network for cell functions, such as cell division

deoxyribonucleic acid (DNA)

an organic molecule containing coded instructions for the life processes of an organism, which consists of nucleotides bonded together in the form of a double helix

endomembrane system

a system of membranes suspended within eukaryotic cells to partition the cells into functional compartments, such as the Golgi apparatus and endoplasmic reticulum

endoplasmic reticulum (ER)

a network of membranes that helps process molecules in a cell and transports cell materials; may be rough (with ribosomes attached) or smooth (without ribosomes attached)

eukaryote

an organism characterized by membrane-bound organelles, such as the nucleus

flagellum (plural, flagella)

threadlike tail that allows some cells to move; structure differs between prokaryotes and eukaryotes

Golgi apparatus

an organelle that attaches chemical markers to molecules produced in the endoplasmic reticulum in order to transport the molecules to their places inside or outside a cell

junction

a point at which cells are bound together

lysosome

an organelle that digests bacteria that enter a cell, eliminates toxins, and recycles unneeded cell materials

mitochondrion (plural, mitochondria)

an organelle that changes energy from food into energy a cell can use

nucleoid

the area inside a prokaryotic cell where genetic material (DNA) is found

nucleolus (plural, nucleoli)

a site within the nucleus where ribosomal subunits are assembled before export to the cytoplasm

nucleus (plural, nuclei)

a membrane-bound organelle that contains most of the genetic material (DNA); this structure directs a cell's growth, division, and death

organelle

a structure in a cell that has a specific task, such as a mitochondrion or Golgi apparatus

peroxisome

a structure in eukaryotes that transforms fatty acids into sugars and aids chloroplasts in oxidizing plant sugars

pilus (plural, pili)

short, hairlike projection found on the surface of many bacteria that helps cells stick together; longer pili can transfer DNA from cell to cell

prokaryote

a unicellular organism with no internal membrane-bound structures

ribosome

a structure composed of RNA and protein that constructs proteins based on the instructions provided by DNA; may be free-floating in cytoplasm or attached to form rough endoplasmic reticulum