Ch. 4 Flashcards
(48 cards)
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