Chapter 6 Terms Flashcards
Organelles
Any of several membrane-enclosed structures with specialized functions, suspended in the cytosol of eukaryotic cells
Electron microscope (EM)
A microscope that uses magnets to focus an electron beam on or through a specimen, resulting in a practical resolution of a hundredfold greater that 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 cell surfaces
Scanning electron microscopy (SEM)
A microscope that uses an electron beam to scan the surface of a sample, coated with metal atoms, to study details of its topography
Transmission electron microscope (TEM)
A microscope that passes an electron beam through very thin sections stained with metal atoms and is primarily used to study the internal ultra structure of cells
Cell fractionation
The disruption of a cell and separation of its parts by centrifugation at successively higher speeds
Cytosol
The semifluid portion of the cytoplasm
Eukaryotic cell
A type of cell with a membrane-enclosed nucleus and membrane-enclosed organelles. Organisms with eukaryotic cells (protists, plants, fungi, and animals) are called eukaryotes
Prokaryotic cell
A type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles. Organisms with prokaryotic cells (bacteria and archaea) are called prokaryotes
Nucleoid
A non-membrane-bounded region in a prokaryotic cell where the DNA is concentrated
Cytoplasm
The contents of the cell bounded by the plasma membrane; in eukaryotes, the portion exclusive of the nucleus
Plasma membrane
The membrane at the boundary of every cell that acts as a selective barrier, regulating the cell’s chemical comp
Light microscope (LM)
An optical instrument with lenses that refract (bend) visible light to magnify images of specimens
Nucleus
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 neurons
Nuclear envelope
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 lamina
A netlike array of protein filaments that lines the inner surface of the nuclear envelope and helps maintain the shape of the nucleus
Chromosome
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
Chromatin
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.
Nucleolus
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. See also ribosome.
Ribosomes
A complex of rRNA and protein molecules that functions as a site of protein synthesis in the cytoplasm; consists of a large and a small subunit. In eukaryotic cells, each subunit is assembled in the nucleolus. See also nucleolus.
Endomembrane system
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.
Vesicles
A membranous sac in the cytoplasm of a eukaryotic cell.
Endoplasmic reticulum (ER)
An extensive membranous network in eukaryotic cells, continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome-free (smooth) regions.
Smooth ER
That portion of the endoplasmic reticulum that is free of ribosomes.
Rough ER
That portion of the endoplasmic reticulum with ribosomes attached.
Glycoprotein
A protein with one or more covalently attached carbohydrates.
Transport vesicles
A small membranous sac in a eukaryotic cell’s cytoplasm carrying molecules produced by the cell.
Golgi apparatus
An organelle in eukaryotic cells consisting of stacks of flat membranous sacs that modify, store, and route products of the endoplasmic reticulum and synthesize some products, notably noncellulose carbohydrates.