cell theory
theory that all living things are composed of cells and that all cells come from other cells
cell wall
a protective layer exterior to the plasma membrane in plant cells, bacteria, fungi, and some protists; protects the cell and helps maintain its shape
cellular metabolism
all the chemical activities of the cell
central vacuole
in a plant cell, a large membraneous sac w/ diverse roles in growth and the storage of chemicals and waste
centriole
a structure in an animal cell composed of cylinders of microtubule triplets arranges in a 9+0 pattern. An animal usually has a centrosome w/ these involved in cell division
chloroplast
an organelle found in plants and photosynthetic protists that absorbs sunlight and uses it to drive the synthesis of organic molecules (sugars) from CO2 and water
chromatin
the combination of DNA and proteins that constitutes eukaryotic chromosomes; often used to refer to the diffuse, very extended form taken by chromosomes when cell is not dividing
chromosome
a threadlike, gene-carrying structure found in the nucleus of a eukaryotic cell and most
cilia
short cellular appendage specialized for locomotion, formed from a core of 9 outer doublet microtubules (the 9+2 pattern)covered by the cell's plasma membrane
crista (pl cristae)
an infolding of the inner mitochondrial membrane
cytoplasm
the contents of a eukaryotic cell btwn the plasma membrane and the nucleus, consists of a semifluid medium and organelles; can also refer to the interior of a prokaryotic cell
cytoskeleton
a network of protein fibers in the cytoplasm of a eukaryotic cell; includes microfilaments, intermediate filaments, and microtubules
electron microscope (EM)
a microscope that uses magnets to focus an electron beam through, or onto the surface of, a specimen, An electron microscope achieves a 100fold greater resolution than a light microscope
endomembrane system
a network of membranes inside and around a eukaryotic cell, related either through direct physical contact or by the transfer of membraneous vesicles
endoplasmic reticulum (ER)
an extensive membraneous network in a eukaryotic cell, continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome-free (smooth) regions
endosymbiont theory
a theory that mitochondria and chloroplasts originated as prokaryotic cells engulfed by an ancestor eukaryotic cell. The engulfed cell and its host cell then evolved into a single organism
eukaryotic cell
a cell w/ membrane-enclosed nucleus and organelles. = all organisms except bacteria and archea
extracellular matrix (ECM)
the meshwork surrounding animal cells; consists of glycoproteins and polysaccharides
flagellum (pl flagella)
a long cellular appendage specialized for locomotion. differs in prokaryotes and eukaryotes in structure and function. Like cilia, it has a 9+2 arrangement of microtubules covered by the cell's plasma membrane
glycoprotein
a protein w/ one or more short chains of sugars attached
Golgi apparatus
an organelle in eukaryotic cells consisting of stacks of membrane sacs that modify, store, and ship products of the endoplasmic reticulum
granum (pl grana)
a stack of membrane-brounded thylakoids in a chloroplast. They are the sites where light energy is trapped by chlorophyll and converted to chemical energy during the light reactions of photosynthesis
integrins
a transmembrane protein that interconnects the extracellular matrix and the cytoskeleton
intermediate filament
an medium-sized protein fiber that is one of the 3 main kinds of fibers making up the cytoskeleton of eukaryotic cells. they are ropelike, made of fibrous proteins
light microscope (LM)
an optical instrument with lenses that refract (bend) visible light to magnify images and project them into a viewer's eye or onto photographic film
lysosome
a digestive organelle in eukaryotic cells; contains hydrolytic enzymes that digest engulfed food or damaged organelles
microfilament
the thinnest of 3 main kinds of protein fibers making up the cytoskeleton of a eukaryotic cell; a solid, helical rod composed of the globular protein actin
microtubule
the thickest of 3 main kinds of protein fibers making up the cytoskeleton of a eukaryotic cell; a hollow tube made of globular proteins called tubulins; found in cilia and flagella
mitochondrial matrix
the compartment of the mitochondrion enclosed by the inner membrane and containing enzymes and substrates for the citric acid style
mitochondrion
an organelle in eukaryotic cells where cellular respiration occurs. Enclosed by 2 membranes, it is where most of the cell's ATP is made
nuclear envelope
a double membrane that incloses the nucleus, perforated with pores that regulate traffic with the cytoplasm
nucleoid
a dense region of DNA in a prokaryotic cell
nucleolus
a structure within the nucleus where ribosomal RNA is made and assembled with proteins imported from the cytoplasm to make ribosomal subunits
nucleus (pl nuclei)
sn stom's central core, containing protons and neutrons, and the genetic control center of a eukaryotic cell
organelle
a membrane-enclosed structure w/ a specialized function w/ in a cell
peroxisome
an organelle containing enzymes that transfer hydrogen atoms from various substrates to oxygen, producing and then degrading hydrogen peroxide
plasma membrane
the membrane at the boundary of every cel that acts as a selective barrier to the passage of ions and molecules into and out of the cell, consists of a phospholipid bilayer with embedded proteins
plasmodesma (pl plasmodesmata)
an open channel in a plant cell wall through which strands of cytoplasm connect from adjacent cells
prokaryotic cell
cell lacking membrane enclosed nucleus and oragnelles, found only in Bacteria and Archaea
ribosome
a cell structure consisting of RNA and protein organized into two subunits and functioning as the site of protein synthesis in the cytoplasm. In eukaryotic cells, they are constructed int the nucleus
rough endoplasmic reticulum
the portion of endoplasmic reticulum w/ ribosomes attached that make membrane proteins and secretory proteins
scanning electron microscope (SEM)
microscope that uses an electron beam to study the fine details of cell surfaces or other specimens
smooth endoplasmic reticulum
portion of endoplasmic reticulum that lacks ribosomes
stroma
the dense fluid within the chloroplast that surrounds they thylakoid membrane and is involved in the synthesis of organic molecules from carbon dioxide and water. Sugars are made here by the enzymes of the Calvin cycle
thylakoid
a flattened membranous sac inside a chloroplast. These membranes contain chlorophyll and the molecular complexes of the light reactions of photosynthesis. a stack of these is a granum
transmission electron microscope (TEM)
microscope that uses an electron beam to study the internal structure of thinly sectioned specimens
transport vesicle
a small membranous sac in a eukaryotic cell's cytoplasm carrying molecules produced by the cell. it buds from the endoplasmic reticulum or Golgi and eventually fuses w/ another organelle or the plasma membrane, releasing its contents
vacuole
a mebrane-enclosed sac that is part of the endomembrane system of a eukaryotic cell and has diverse functions
vesicle
a sac made of membrane in the cytoplasm of a eukaryotic cell