Chapter 4 Vocab Flashcards
an optical instrument with lenses that refract (bend) visible light to magnify images of specimens
light microscope (LM)
any of several membrane-enclosed structures with specialized functions, suspended in the cytosol of eukaryotic cells
organelle
a microscope that uses magnets to focus an electron beam on or through a spectrum, resulting in a practical resolution of a hundredfold greater than that of a light microscope using standard techniques. A transmission electron microscope (TEM) is used to study the internal structure of thin sections of cells. A scanning electron microscope (SEM) is used to study the fine details of the cell surface.
electron microscope (EM)
a microscope that uses an electron beam to scan the surface of the sample, coated with metal atoms, to study details of its topography
scanning electron microscope (SEM)
a microscope that passes electron beam through very thin sections stained with metal atoms and is primarily used to study the internal ultrastructure of cells
transmission electron microscope (TEM)
the disruption of a cell and separation of its parts by centrifugation at successively higher speeds
cell fractionation
the contents of the cell bounded by the plasma membrane; in eukaryotes, the portion exclusive of the nucleus
cytosol
a type of cell with membrane-enclosed nucleus and membrane-enclosed organelles. Organisms with eukaryotic cells (protists, fungi, and animals) are called eukaryotes
eukaryotic cell
No nucleus
prokaryotic cell
a non-membrane-bounded region in a prokaryotic cell where the DNA is concentrated
nucleoid
the contents of the cell bounded by the plasma membrane; in eukaryotes, the portion exclusive of the nucleus
cytoplasm
the membrane at the boundary of every cell that acts as a selective barrier, regulating the cell’s chemical composition
plasma membrane
an atom’s central core, containing protons and neutrons; the organelle of a eukaryotic cell that contains the genetic material in the form of chromosomes, made up of chromatin; a cluster of neutrons
nucleus
in a eukaryotic cell, the double membrane that surrounds the nucleus, perforated with pores that regulate traffic with the cytoplasm. The outer membrane is continuous with the endoplasmic reticulum
nuclear envelope
a netlike array of protein filaments that lines the inner surface of the nuclear envelope and helps maintain the shape of the nucleus
nuclear lamina
a cellular structure carrying genetic material, found in the nucleus of eukaryotic cells. Each chromosome consists of one very long DNA molecule and associated proteins (a bacterial chromosome usually consists of a single circular DNA molecule and associated proteins. It is found in the nucleoid region, which is not membrane bounded.
chromosome
the complex of DNA and proteins that makes up eukaryotic chromosomes. When the cell is not dividing, chromatin exists in its dispersed form, as a mass of very long, thin fibers that are not visible with a light microscope
chromatin
a specialized structure in the nucleus, consisting of chromosomal regions containing ribosomal RNA (rRNA) genes along with ribosomal proteins imported from the cytoplasm; site of rRNA synthesis and ribosomal subunit assembly
nucleolus
a complex of rRNA and protein molecules that function as a site of protein synthesis in the cytoplasm; consists of a large and small subunit. In eukaryotic cells, each subunit is assembled in the nucleolus
ribosome
the collection of membranes inside and surrounding a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles; includes the plasma membrane, the nuclear envelope, the smooth and rough endoplasmic reticulum, the Golgi apparatus, lysosomes, vesicles, and vacuoles
endomembrane system
a membranous sac in the cytoplasm of a eukaryotic cell
vesicle
an extensive membranous network in eukaryotic cells, continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome-free (smooth) regions
endoplasmic reticulum (ER)
the portion of the ER that is free of ribosomes
smooth ER
the portion of the ER with ribosomes attached
rough ER
a protein with one or more covalently attached carbohydrates
glycoprotein
a small membranous sac in a eukaryotic cell’s cytoplasm carrying molecules produced by the cell
transport vesicle