Ch.4 Flashcards
Cell theory
The theory that all living things are composed of cells and that all cells come from other cells
Cell wall
A protective layer external to the plasma membrane in plant cells, bacteria, fungi, and some protists; protects the cell and helps maintain its shape
Cellular metabilism
All the chemical activities of a cell
Central vacuole
In a plant cell, a large membranous sac with diverse roles in growth and the storage of chemicals and wastes
Centrosome
The region of a duplicated chromosome where two sister chromatids are joined (often appearing as a narrow “waist”) and where spindle microtubules attach during mitosis and meiosis. The centromere divides at the onset of anaphase during mitosis and anaphase II during meiosis
Chloroplast
An organelle found in plants and algae that absorbs sunlight and uses it to drive the synthesis of organic compounds (sugars) from carbon dioxide and water
Chromatin
The complex of DNA and proteins that makes up eukaryotic chromosomes; often used to refer to the diffuse, very extended form taken by chromosomes when a cell is not dividing
Chromosome
A gene-carrying structure found in the nucleus of a eukaryotic cell and most visible during mitosis and meiosis; also, the main gene-carrying structure of a prokaryotic cell
Cilium (Cilia)
A short cellular appendage specialized for locomotion or moving fluid past the cell, formed from a core of nine outer doublet microtubules and two single microtubules (the “9 + 2” arrangement) covered by the cell’s plasma membrane
Cytoplasm
The contents of a eukaryotic cell between the plasma membrane and the nucleus; consists of a semifluid medium and organelles; can also refer to the interior of a prokaryotic cell
Cytoskeleton
A network of protein fibers in the cytoplasm of a eukaryotic cell; includes microfilaments, intermediate filaments, and microtubules
Cytosol
The semifluid portion of the cytoplasm
Electron microscope (EM)
A microscope that uses magnets to focus an electron beam through, or onto the surface of, a specimen. An electron microscope achieves a hundredfold greater resolution than a light microscope
Endomembrane system
A network of membranes inside and surrounding a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles
Endoplasmic reticulum (ER)
An extensive membranous network in a eukaryotic cell, continuous with the outer nuclear membrane and composed of ribosome-studded (rough) and ribosome-free (smooth) regions. See also rough ER; smooth ER
Endosymbiont theory
The theory that mitochondria and chloroplasts originated as prokaryotic cells engulfed by an ancestral eukaryotic cell. The engulfed cell and its host cell then evolved into a single organism
Eukaryotic cell
A type of cell that has a membrane-enclosed nucleus and membrane-enclosed organelles. All organisms except bacteria and archaea are composed of eukaryotic cells
Extracellular matrix (ECM)
The meshwork surrounding animal cells; consists of glycoproteins and polysaccharides synthesized and secreted by cells
Flagellum (Flaggela)
A long cellular appendage specialized for locomotion. The flagella of prokaryotes and eukaryotes differ in both structure and function. Like cilia, eukaryotic flagella have a “9 + 2” arrangement of microtubules covered by the cell’s plasma membrane
glycoprotein
The main components of the ECM, proteins bonded with carbohydrates
Golgi apparatus
An organelle in eukaryotic cells consisting of stacks of membranous sacs that modify, store, and ship products of the endoplasmic reticulum
Granum (grana)
A stack of membrane-bounded thylakoids in a chloroplast. Grana are the sites where light energy is trapped by chlorophyll and converted to chemical energy during the light reactions of photosynthesis
Integrin
A transmembrane protein that interconnects the extracellular matrix and the cytoskeleton in animal cells
Intermediate filament
An intermediate-sized protein fiber that is one of the three main kinds of fibers making up the cytoskeleton of eukaryotic cells. Intermediate filaments are ropelike, made of fibrous proteins
Light microscope (LM)
An optical instrument with lenses that refract (bend) visible light to magnify images and project them into a viewer’s eye or onto photographic film
Lysosome
A digestive organelle in eukaryotic cells; contains hydrolytic enzymes that digest engulfed food or damaged organelles
Microfilament
The thinnest of the three main kinds of protein fibers making up the cytoskeleton of a eukaryotic cell; a solid, helical rod composed of the globular protein actin
Microtubule
The thickest of the three main kinds of fibers making up the cytoskeleton of a eukaryotic cell; a hollow tube made of globular proteins called tubulins; found in cilia and flagella
Mitochondiral matrix
The compartment of the mitochondrion enclosed by the inner membrane and containing enzymes and substrates for the citric acid cycle
Mitochondrian (Mitochondria)
An organelle in eukaryotic cells where cellular respiration occurs. Enclosed by two membranes, it is where most of the cell’s ATP is made
Motor protein
A protein that interacts with the cytoskeleton and other cell components, producing movement of the whole cell or parts of the cell
Nuclear envelope
A double membrane that encloses the nucleus, perforated with pores that regulate traffic with the cytoplasm
Nucleoid
A non–membrane-bounded region in a prokaryotic cell where the DNA is concentrated
Nuclolous
A structure within the nucleus where ribosomal RNA is made and assembled with proteins imported from the cytoplasm to make ribosomal subunits
Nucleus (Nuclei)
(1) An atom’s central core, containing protons and neutrons. (2) The organelle of a eukaryotic cell that contains the genetic material in the form of chromosomes, made of chromatin
Organelle
A membrane-enclosed structure with a specialized function within a cell
Peroxisome
An organelle containing enzymes that transfer hydrogen atoms from various substrates to oxygen, producing and then degrading hydrogen peroxide
Plasma membrane
The membrane at the boundary of every cell that acts as a selective barrier to the passage of ions and molecules into and out of the cell; consists of a phospholipid bilayer with embedded proteins
Plasmodesma
An open channel in a plant cell wall that connects the cytoplasm of adjacent cells
Prokaryotic cell
A type of cell lacking a membrane-enclosed nucleus and other membrane-enclosed organelles; found only in the domains Bacteria and Archaea
Ribisome
A cell structure consisting of RNA and protein organized into two subunits and functioning as the site of protein synthesis in the cytoplasm. In eukaryotic cells, the ribosomal subunits are constructed in the nucleolus
Rough ER
The portion of the endoplasmic reticulum with ribisomes attached to make membrane proteins and secratory proteins
Scanning Electron microscope (SEM)
A microscope that uses an electron beam to study the surface details of a cell or other specimens
Smooth ER
The portion of the endoplasmic reticulum that lacks ribisomes
Stroma
The dense fluid within the chloroplast that surrounds the thylakoid membrane. Sugars are made in the stroma by the enzymes of the Calvin cycle
Thylakoid
A flattened membranous sac inside a chloroplast. Thylakoid membranes contain chlorophyll and the molecular complexes of the light reactions of photosynthesis. A stack of thylakoids is called a granum
Transmission electron microscope (TEM)
A microscope that uses an electron beam to study the internal structure of thinly sectioned specimens
Transport vesicle
A small membranous sac in a eukaryotic cell’s cytoplasm carrying molecules produced by the cell. The vesicle buds from the endoplasmic reticulum or Golgi and eventually fuses with another organelle or the plasma membrane, releasing its contents
Vacuole
A membrane-enclosed sac that is part of the endo-membrane system of a eukaryotic cell and has diverse functions in different kinds of cells
Vesicle
A sac made of membrane in the cytoplasm of a eukaryotic cell
