light microscope
LM
an optical instrument w/ lenses that refract (bend) visible light to magnify images & project them into a viewer's eye or onto photographic film
cell theory
the theory that all living things r composed of cells & that all cells come from other cells
electron microscope
EM
an instrument that focuses an electron beam through, or onto the surface of, a specimen
an electron microscope achieves a hundredfold greater resolution than a light microscope
scanning electron microscope
SEM
a microscope that uses an electron beam to study the surface architecture of a cell or other specimen
transmission electron microscope
TEM
a microscope that uses an electron beam to study the internal structure of thinly sectioned specimens
prokaryotic cell
a type of cell lacking a membrane-enclosed nucleus & other membrane-enclosed organelles
found only in the domains Bacteria & Archaea
eukaryotic cell
a type of cell that has a membrane-enclosed nucleus & other membrane-enclosed organelles
all organisms except bacteria & archaea are composed of eukaryotic cells
plasma membrane
the membrane that sets a cell off from its surroundings & acts as selective barrier to the passage of ions & molecules into & out of the cell
consists of a phospholipid bilayer in which r embedded molecules of protein & cholesterol
chromosome
a threadlike, gene-carrying structure found in the nucleus of a eukaryotic cell & most visible during mitosis & meiosis
the main gene-carrying structure of a prokaryotic cell
consist of chromatin, a combo of DNA and protein
ribosome
a cell structure consisting of RNA and protein organized into 2 subunits & functioning as the site of protein synthesis in the cytoplasm
the ribosomal subunits r constructed in the nucleolus
cytoplasm
everything inside a cell b/w the plasma membrane & the nucleus
consists of a semifluid medium & organelles
nucleoid
a dense region of DNA in a prokaryotic cell
flagellum (flagella)
a long cellular appendage specialized for locomotion
the flagella of prokaryotes & eukaryotes differ in both structure & function - like cilia, eukaryotic flagella have a 9+2 arrangement of microtubules covered by the cell's plasma membrane
organelle
a membrane-enclosed structure w/ a specialized function w/in a cell
cellular metabolism
the chemical activities of cells
nucleus (nuclei)
the genetic control center of a eukaryotic cell
chromatin
the complex of DNA & proteins that constitutes eukaryotic chromosomes
often used to refer to the diffuse, very extended form taken by chromosomes when a cell isn't dividing
nuclear envelope
a double membrane, perforated w/ pores, which encloses the nucleus & separates it from the rest of the eukaryotic cell
nucleolus
a structure w/in the nucleus of a eukaryotic cell where ribosomal RNA is made & assembled w/ proteins imported from the cytoplasm to make ribosomal subunits
endomembrane system
a network of membranes inside & around a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles
vesicle
a sac made of membrane in the cytoplasm of a eukaryotic cell
endoplasmic reticulum
ER
an extensive membranous network in a eukaryotic cell, continuous w/ the outer nuclear membrane & composed of ribosome-studded (rough) & ribosome-free (smooth) regions
smooth endoplasmic reticulum
SER
a network of interconnected membranous tubulues in a eukaryotic cell's cytoplasm
lacks ribosomes
rough endoplasmic reticulum
RER
a network of interconnected membranous sacs in a eukaryotic cell's cytoplasm
membranes r studded w/ ribosomes that make membrane proteins & secretory proteins
Golgi apparatus
an organelle in eukaryotic cells consisting of stacks of membranous sacs that modify, store, & ship products of the endoplasmic reticulum
lysosome
a digestive organelle in eukaryotic cells
contains hydrolytic enzymes that digest the cell's food & wastes
vacuole
a membrane-enclosed sac that's part of the endomembrane system of a eukaryotic cell, having diverse functions
central vacuole
a membrane-enclosed sac occupying most of the interior of a mature plant cell, having diverse roles in reproduction, growth, & development
peroxisome
an organelle containing enzymes that transfer hydrogen from various substrates to oxygen, producing and then degrading hydrogen peroxide
mitochondrion (mitochondria)
an organelle in eukaryotic cells where cellular respiration occurs
enclosed by 2 concentric membranes
where most of the cell's ATP is made
