Inside the Cell
cilium
A hairlike structure arranged in tightly packed rows that projects from the surface of some cells.
gap junction
A type of intercellular junction in animal cells that allows the passage of material or current between cells.
rough ER
ER (endoplasmic reticulum) that is dotted with ribosomes
endoplasmic reticulum
a cell structure that forms a maze of passageways in which proteins and other materials are carried from one part of the cell to another
plasmodesmata
a cell-to-cell junction in plants that connects the cytoplasm of adjacent cells
nuclear envelope
a double membrane that surrounds the nucleus in the cell
secretion
a functionally specialized substance (especially one that is not a waste) released from a gland or cell
cytoplasm
a jellylike fluid inside the cell in which the organelles are suspended
flagellum
a lash-like appendage used for locomotion (e.g., in sperm cells and some bacteria and protozoa)
vesicle
a membrane bound sac that contains materials involved in transport of the cell.
thykaloid
a membrane system found within chloroplasts that contains the components for photosynthesis
motor protein
a protein that interacts with cytoskeletal elements and other cell components, producing movement of the whole cell or parts of the cell.
fimbria
a short, hairlike appendage of a prokaryotic cell that helps it adhere to the substrate or to other cells; also known as an attachment pilus.
organelle
a specialized part of a cell
capsule
a sticky, gelatinous substance around the cell wall; allows cells to stick together or to the host cell
cell wall
a thin membrane around the cytoplasm of a cell
chromosome
a threadlike body in the cell nucleus that carries the genes in a linear order
transport vesicle
a tiny membranous sac in a cell's cytoplasm carrying molecules produced by the cell
prokaryotic cell
a type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles.
tight junction
a type of intercellular junction in animal cells that prevents the leakage of material between cells
lyosome
a vesicle that buds from the Golgi apparatus, contains digestive enzymes that break down large molecules
mitochondrion
an organelle containing enzymes responsible for producing energy
vacuole
cell organelle that stores materials such as water, salts, proteins, and carbohydrates
eukaryotic cell
cell with a nucleus (surrounded by its own membrane) and other internal organelles
stroma
dense fluid within the chloroplast
cell theory
idea that all living things are composed of cells, cells are the basic units of structure and function in living things, and new cells are produced from existing cells
conjugation pili
in a bacterium, elongated, hollow appendage used to transfer DNA to other cells
cristae
inner foldings of the inner membrane of mitochondria
adhesion junction
junction between cells in which the adjacent plasma membranes do not tough but are help together by intercellular filaments attached to buttonlike thickenings
surface-area-to-volume-ratio
limits cell size
chromatin
long strands of DNA found in the eukaryotic cell nucleus; condense to form chromosomes
centrosome
material present in the cytoplasm of all eukaryotic cells, important during cell division; the microtubule-organizing center.
cytoskeleton
network of protein filaments within some cells that helps the cell maintain its shape and is involved in many forms of cell movement
adenosine triphosphate (ATP)
one of the principal chemical compounds that cells use to store and release energy
centriole
one of two tiny structures located in the cytoplasm of animal cells near the nuclear envelope
nuclear pore
opening in the nuclear envelope that permits the passage of proteins into the nucleus and ribosomal subunits out of the nucleus
chloroplast
organelle found in cells of plants and some other organisms that captures the energy from sunlight and converts it into chemical energy
cellular respiration
process that releases energy by breaking down glucose and other food molecules in the presence of oxygen
actin filament
protein fibers that play a role in movement of cell and organelles
nucleoid
shaped like or having the appearance of a nucleus
ribosome
small particle in the cell on which proteins are assembled; made of RNA and protein
Golgi apparatus
stack of membranes in the cell that modifies, sorts, and packages proteins from the endoplasmic reticulum
microtubule
straight, hollow tube of proteins that gives rigidity, shape, and organization to a cell
smooth ER
that portion of the endoplasmic reticulum that is free of ribosomes.
endomembrane system
the collection of membranes inside and around a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles; includes the smooth and rough endoplasmic reticulum, the Golgi apparatus, lysosomes, and vacuoles
nucleus
the control center of the cell
matrix
the extracellular substance that gives connective tissues their strength and flexibility. can be solid, semisolid, or liquid
nucleolus
the site where DNA is concentrated when it is in the process of making ribosomal RNA
granum
the smallest particle that is capable of carrying out photosynthesis; the functional unit of a chloroplast
extracellular matrix (ECM)
the substance in which animal cells are embedded, consisting of protein and polysaccharides synthesized and secreted by cells.
plasma membrane
thin outer boundary of a cell that regulates the traffic of chemicals between the cell and its surroundings
