Chapter 6: A Tour of the Cell Flashcards
Light Microscope (LM)
Optical instrument with lenses that refract (bend) visible light to magnify images of specimens
Organelle
- Membrane-enclosed structures
- Have specialized functions
- Suspended in the cytosol of eukaryotic cells
Electron Microscope (EM)
Microscope that uses magnets to focus an electron beam on or through a specimen, resulting in practical resolution that is 100-fold greater than that of a light microscope using standard techniques
Scanning Electron Microscope (SEM)
Microscope that uses an electron beam to scan the surface of a sample, coatec with metal atoms, to study details of its topography (surface)
Transmission Electron Microscope (TEM)
- Microscope that passes an electron beam through very thin sections stained with metal atoms
- Primarily used to study the internal ultrastructure of cells
Cell Fractionation
Disruption of a cell and separation of its parts by centrifugation at successively higher speeds
Cytosol
Semifluid portion of the cytoplasm
Eukaryotic Cell
- Type of cell with a membrane-enclosed nucleus and membrane-enclosed organelles
- Examples of organisms with these cells include fungi, protists, plants, and animals
Prokaryotic Cell
- Type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles
- Only found in the domains Bacteria and Archaea
Cytoplasm
- Contents of the cell bounded by the plasma membrane
- In eukaryotes, the portion exclusive of the nucleus
Plasma Membrane
- Membrane at the boundary of every cell that acts as a selective barrier
- Regulates the cell’s chemical composition
Nucleus
Organelle of a eukaryotic cell that contains the genetic material in the form of chromosomes, made up of chromatin
Nuclear Envelope
- In a eukaryotic cell
- Double membrane that surrounds the nucleus
- Perforated with pores that regulate traffic with the cytoplasm
- Outer membrane is continuous with the endoplasmic reticulum
Chromosome
- Cellular structure consisting of one DNA molecule and associated with protein molecules
- Eukaryotic cell usually has many while prokaryotic cell has one
Chromatin
- Complex of DNA and proteins that makes up eukaryotic chromosomes
- Not visible under a microscope when in its dispersed form (when the cell is in interphase)
Nucleolus
- Specialized structure in the nucleus
- Consists of chromosomal regions containing ribosomal RNA (rRNA) genes along with ribosomal proteins imported from the cytoplasm
Ribosome
- 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
Endomembrane System
- Collection of membranes inside and surrounding a eukaryotic cell, related through either direct physical contact or by the transfer of membranous vesicles
- Includes the plasma membrane, nuclear envelope, the smoot and rough endoplasmic reticulum, the Golgi apparatus, lysosomes, vesicles, and vacuoles
Vesicle
A membranous sac in the cytoplasm of a eukaryotic cell
Endoplasmic Reticulum (ER)
- Extensive membranous network in eukaryotic cells
- Continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome free (smooth) regions
Smooth Endoplasmic Reticulum (Smooth ER)
The portion of the endoplasmic reticulum that is free of ribosomes
Rough Endoplasmic Reticulum (Rough ER)
The portion of the endoplasmic reticulum with ribosomes attached
Glycoprotein
A protein with one or more covalently attached carbohydrates
Transport Vesicle
- Small membranous sac in a eukaryotic cell’s cytoplasm
- Carries molecules produced by the cell
Golgi Apparatus
- Organelle in eukaryotic cells consisting of flat membranous sacs
- Modifies, stores, and routes products of the endoplasmic reticulum and synthesizes some products (notably no cellulose carbohydrates)
Lysosome
- Membrane-enclosed sac of hydrolytic enzymes
- Found in the cytoplasm of animal cells and some protists