Ch.6 A Tour of the Cell Flashcards
Light Microscope
An optical instrument with lenses that refract (bend) visible light to magnify images of specimens
Organelles
Any of several membranes-enclosed structures with specialized functions, suspended in the cytosol of eukaryotic cells
Electron Microscope
A microscope that uses magnets to focus an electron beam on/through a specimen, resulting in a practical resolution that is 100x greater than a light microscope
Transmission Electron Microscope
A microscope that passes an electron beam through very thin sections stained w/metal atoms and is primarily used to study the internal structure of cells
Cell Fractionation
The disruption of a cell and separation of its parts by centrifugation at successively higher speeds
Cells
The basic structural and functional units of every organism
Cytosol
Semifluid portion of the cytoplasm in which subcellular components are suspended
Nucleoid
A non-membrane enclosed region in a prokaryotic cell where its chromosome is located
Eukaryotic Cell
A type of cell with a membrane-enclosed nucleus and membrane-enclosed organelles
Prokaryote Cell
A type of cell lacking a membrane-enclosed nucleus and membrane-enclosed organelles
Fimbriae
Attachment structures on the surface of some prokaryotes
Cell Wall
Rigid structure outside the plasma membrane
Glycocalyx
Outer coating of many prokaryotes consisting of a capsule or a slime layer
Flagella
Locomotion organelles of some prokaryotes
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 composition
Microvilli
Long, thin projections from cells surface which increase surface area without an appreciable increase in volume
Nucleus
Organelle of a eukaryotic cell that contains the genetic material in the form of chromosomes, made up of chromatin
Nuclear Envelope
The double membrane that surrounds the nucleus, perforated with pores that regulate traffic with the cytoplasm. The outer membrane is continuous with the ER
Pore Complex
A protein structure that lines each pore and plays an important role in regulating the entry and exit of proteins and RNAs, as well as large complexes of macromolecules
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
Nuclear Matrix
A framework of protein fibers extending throughout the nuclear interior
Chromosomes
Structures that carry the genetic information. Each contains one long DNA molecule associated with many proteins.
Nucleolus
A specialized structure in the nucleus, consisting of chromosomal regions containing ribosomal RNA (rRNA) genes along w/ribosomal proteins imported from the cytoplasm; site of rRNA synthesis and ribosomal subunit assembly
Ribosomes
A complex of rRNA and protein molecules that functions as a site of protein synthesis in the cytoplasm; consists of a large and small subunit
Free Ribosomes
Are suspended in the cytosol and make proteins that function within the cytosol
Bound Ribosomes
Ribosomes that are attached to the outside of the ER or nuclear envelope
Functions of Bound Ribosomes
Make proteins that are destined for insertion into membranes, packaging within certain organelles such as lysosomes, or export from the cell (secretion)
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
Organelles of the Endomembrane System
Nuclear Envelope
Endoplasmic Reticulum
Golgi Apparatus
Lysosomes
Vacuoles
Plasma Membrane
Vesicle
A membranous sac in the cytoplasm of the eukaryotic cell whose job is to pinch off from one membrane, transport proteins to another organelle, and then fuse with it
Endoplasmic Reticulum (ER)
An extensive membranous network in eukaryotic cells, continuous w//the outer nuclear membrane and composed of ribosome studded (rough) and ribosome free (smooth) regions
Smooth ER
Portion of ER that is free of ribosomes
Rough ER
Portion of the ER with ribosomes attached
Functions of Smooth ER
Synthesizes lipids
Metabolizes carbohydrates
Detoxifies drugs and poisons
Stores calcium ions
Functions of Rough ER
Is a membrane factory for the cell; all of our membrane proteins are made and inserted into the membrane of the rough ER
Functions of Bound Ribosomes at Rough ER
Make three types of proteins:
Membrane Proteins
Proteins that are going to be exported or secreted by the cell
Proteins that are going to be sent to a specific location
Glycoproteins
A protein w/one or more covalently attached carbohydrates; rough ER ribosomes secrete glycoproteins
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 ER and synthesize some products, notably noncellulose carbohydrates
Functions of the Golgi Apparatus
Modifies products of the ER
Manufactures certain macromolecules
Sorts and packages materials into transport vesicles
Cisternae
Flattened membranous sacs in the Golgi
Cis Face of Golgi
Receives vesicles containing ER products
Trans Face of Golgi
Dispatches vesicles
Lysosomes
A membrane-enclosed sac of hydrolytic enzymes found in the cytoplasm of animal cells and some protists
Where are hydrolytic enzymes and lysosomal membranes made?
Made by the rough ER and then transferred to Golgi for further processing
Function of Lysosomes
Carry out intracellular digestion (….)
Phagocytosis
A type of endocytosis in which large particulate substances or small organisms are taken up by a cell. It is carried out by some protists and by certain immune cells of animals
Macrophages
A type of white blood cell that helps defend the body by engulfing and destroying bacteria and other invaders
Autophagy
When lysosomes use enzymes to recycle the cell’s organelles and macromolecules; by digesting big macromolecules/polymers, the monomers can then move out of the food vacuole and into the cytosol and can be used for the cell
Food Vacuoles
Formed by phagocytosis; a lysosome fuses w/the food vacuole and digests the molecules; afterward, it can fuse w/the plasma membrane and dump any materials that might be left inside
Lipases
A digestive enzyme that breaks down certain lipids
Vacuoles
A membrane-bounded vesicle whose specialized function varies in different kinds of cells; is formed when two vesicles fuse
Contractile Vacuoles
A membranous sac that helps move excess water out of certain freshwater protists
Central Vacuole
In a mature plant cell, a large membranous sac w/diverse roles in growth, storage, and sequestration of toxic substances
Cell Sap
Solution inside the central vacuole; is the plant cell’s main repository of inorganic ions including potassium and chloride
Cristae
An infolding of the inner membrane of a mitochondrion; The inner membrane houses electron transport chains and molecules of the enzyme catalyzing the synthesis of ATP
Intermembrane Space of Mitochondria
Region between the inner and outer membranes
Mitochondrial Matrix
The compartment of the mitochondrion enclosed by the inner membrane, containing enzymes and substrates for the citric acid cycle, and ribosomes and DNA
Mitochondria
An organelle in eukaryotic cells that serves as the site of cellular respiration, uses oxygen to break down organic molecules and synthesizes ATP
Chloroplasts
An organelle found in plants and photosynthetic protists that absorbs sunlight and uses it to drive the synthesis of organic compounds from carbon dioxide to water; converts solar energy to chemical energy
Endosymbiont Theory
Mitochondria and plastids, including chloroplasts, originated as prokaryotic cells engulfed by a host cell, then evolved into a single organism
Endosymbiont
A cell living within another cell
Similarities Between Mitochondria and Chloroplasts
Have two membranes surrounding them
Contain ribosomes as well as circular DNA molecules associated w/their inner membranes
Autonomous organelles that grow and reproduce within the cell
Thylakoids
A flattened membranous sac inside a chloroplast; their membranes contain molecular “machinery” used to convert light energy to chemical energy
Grana
A stack of membrane-bounded thylakoids in the chloroplast; they function in the light reactions of photosynthesis
Stroma
The dense fluid within the chloroplast surrounding the thylakoid membrane and containing ribosomes and DNA; is involved in the synthesis of organic molecules from carbon dioxide and water
Three Compartments of the Chloroplast
Intermembrane space
Stroma
Thylakoid space
Plastid
One of a family of closely related organelles that include chloroplasts, chromoplasts, and amyloplasts; plastids are found in cells of photosynthetic eukaryotes
Amyloplast
Colorless organelle that stores starch (amylose), particularly in roots and tubers
Chromoplast
Has pigments that give fruits and flowers their orange and yellow hues
Peroxisme
An organelle containing enzymes that transfer hydrogen atoms from various substrates to oxygen (O2), producing and then degrading hydrogen peroxide (H2O2); some peroxisomes use oxygen to break fatty acids down into smaller molecules
Role of Peroxisomes in Liver
Detoxify alcohol and other harmful compounds by transferring hydrogen from the poisonous compounds to oxygen
Glyoxysomes
Specialized peroxisomes that are found in fat-storing tissues of plant seeds; contain enzymes that initiate the conversion of fatty acids to sugar, which the seedling uses as a source of energy
Cytoskeleton
A network of microtubules, microfilaments, and intermediate filaments that extend throughout the cytoplasm and serve a variety of mechanical, transport, and signaling functions
Cell Motility
Includes both changes in cell location and movements of cell parts; generally requires interaction of the cytoskeleton w/motor proteins
Motor Proteins
A protein that interacts w/cytoskeletonal elements and other cell components, producing movement of the whole cell or parts of the cell
Mictrotubules
A hollow rod composed of tubulin proteins that make up part of the cytoskeleton in all eukaryotic cells and is found in cilia and flagella
Tubulin Protein
A dimer (a molecule made up of two subunits ); consists of two slightly different polypeptides, a tubulin and B tubulin
Centrosome
A structure present in the cytoplasm of animal cells that functions as a microtubule-organizing center and is important during cell division; centrosome has two centrioles
Centrioles
A structure in the centrosome of an animal cell composed of a cylinder of microtubule triplets arranged in a “9+0” pattern; centrioles are each composed of nine sets of triplet microtubules arranged in a ring
Flagella
A long cellular appendage specialized for locomotion. Like motile cilia, eukaryotic flagella have a core w/nine other doublet microtubules (the “9+2” arrangement) ensheathed in an extension of the plasma membrane
Cilia
A short appendage containing microtubules in eukaryotic cells. A motile cilium is specialized for locomotion or moving fluid past the cell; it is formed from a core of nine outer doublet microtubules and two inner single microtubules (the “9+2” arrangement) ensheathed in an extension of the plasma membrane
Basal Body
A eukaryotic cell structure consisting of a “9+0” arrangement of microtubule triplets. The basal body may organize the microtubule assembly of a cilium or flagellum and is structurally very similar to a centriole.
Dyneins
A large motor protein extending from one microtubule doublet to the adjacent doublet. ATP hydrolysis drives changes in dynein shape that lead to the bending of cilia and flagella.
Microfilaments
A cable composed of actin proteins in the cytoplasm of almost every eukaryotic cell, making up part of the cytoskeleton and acting alone or w/myosin to cause cell contraction; also called an actin filament
Actin
A globular protein that links into chains, two of which twist helically about each other forming microfilaments (actin filaments) in muscle and other kinds of cells; involved in muscle contractions
Structural Role of Microfilaments
To bear tension (pulling forces) and to help support the cells shape
Cortex
The outer region of cytoplasm in a eukaryotic cell, lying just under the plasma membrane, has a more gel-like consistency than the inner regions due to the presence of multiple microfilaments
Myosin
A type of motor protein that associates into filaments that interact with actin filaments to cause cell contraction
Pesudopodium
A cellular extension of amoeboid cells used in moving and feeding
Cytoplasmic Streaming
A circular flow of cytoplasm, involving interactions of myosin and actin filaments, that speed the distribution of materials within cells
Intermediate Filaments
A component of the cytoskeleton that includes filaments intermediate in size between microtubules and microfilaments; specialized for bearing tension, are more permanent fixtures of cells and play an important role in reinforcing the shape of a cell and fixing the position of certain organelles
Cell wall
A protective layer external to the plasma membrane in the cells of plants, prokaryotes, fungi, and some protists; polysaccharides such as cellulose (in plants), chitin (in fungi), and peptidoglycan (in bacteria) are important structural components of cell walls
Primary Cell Wall
In plants, a relatively thin and flexible layer that surrounds the plasma membrane of a young cell
Middle Lamella
A thin layer of adhesive extracellular material, primarily pectins, found between the primary walls of adjacent young cells; glues adjacent cells together
Secondary Cell Wall
In plant cells, a strong and durable matrix that is often deposited in several laminated layers around the plasma membrane and provides protection and support
Extracellular Matrix
The meshwork of surrounding animal cells, consisting of glycoproteins, polysaccharides, and proteoglycans synthesized and secreted by cells
Glycoproteins
Proteins with covalently bonded carbohydrates, usually short chains of sugars
Collagen
A glycoprotein in the extracellular matrix of animal cells that forms strong fibers, found extensively in connective tissue and bone’ the most abundant protein in the animal kingdom
Proteoglycans
A large molecule consisting of a small core protein w/many carbohydrate chains attached, found in the extracellular matrix of animal cells; collagen fibers are embedded in a network of proteoglycans
Fibronectin
An extracellular glycoprotein secreted by animal cells that helps them attach to the extracellular matrix
Integrins
In animal cells, a transmembrane receptor protein with two subunits that interconnects the extracellular matrix and the cytoskeleton; transmits signals between the ECM and the cytoskeleton and thus integrates changes occurring outside and inside the cell
Plasmodesmata
An open channel through the cell wall that connects the cytoplasm of adjacent plant cells, allowing water, small solutes, and some larger molecules to pass between the cells (unify the plant into one living continuum)
Tight Junctions
A type of intercellular junction between animal cells that prevents the leakage of material through the space between cells
Desmosomes
A type of intercellular junction in animal cells that functions as a rivet, fastening cells together
Gap Junction
A type of intercellular junction in animal cells, consisting of proteins surrounding a pore that allows the passage of materials between the cells
Cell Fractionation
Take cells apart and separates the major organelles from one another
Prokaryotic vs Eukaryotic Cells
Similarities:
Plasma membrane
Semifluid substance called cytosol
Chromosomes
Ribosomes
Differences:
Prokaryotic cells have no nucleus and no membrane-bound organelles
Cocci
Spherical bacteria
Bacilli
Rod-shaped bacteria
Spirilla
Spiral shaped bacteria
Strepto
When bacteria grows and divides and forms chains
Staphylo
When bacteria grows and divides and forms clusters
Amphipathic
Have a polar (hydrophilic) region and a nonpolar (hydrophobic) region; phospholipids are amphipathic
Chromatin
The active form of DNA
Histones
The proteins that the double helix of the DNA wraps around
Nuclear Organizer
Puts ribosomal RNA and proteins together to make ribosomes
Macrophages
Eat bacteria and other things that enter the wound
Chaperonins
Help in the folding of the protein
Tonoplast
The membrane of the central vacuole
Dehydrogenases
Enzymes present in peroxisomes that are going to remove two hydrogens from a molecule and bond it to O2; the intent is to make the R, H202 is a byproduct of the reaction
Catalase
Speeds up the breakdown of hydrogen peroxide into water and oxygen gas
Microtubules Functions
Serve as the tracks to move vesicles and certain organelles from one place to another; maintenance of cell shape; cell motility; chromosome movements in cell division
Microfilaments Functions
Maintenance of cell shape (tension-bearing elements); changes in cell shape; muscle contraction; cytoplasmic streaming in plant cells; cell motility (as in amoeboid movement); division of animal cells
Cell Motility
When cells move from place to place; the cell creeps along because the actin is creating the forces to push the cytosol against the plasma membrane and cause the cell to expand in that area and move slowly forward
Protein Pairs
Actin and myosin
Tubulin and kinesin
Tubulin and dynein
Actin & Mysoin (Microfilaments)
Help muscles do their key work; Working together will move the cytosol and push it out against the plasma membrane, expanding a section of the cell in that direction
Tubulin & Dynein (Microtubules)
Responsible for the bending motion of the cilia and flagella
Tubulin & Kinesin (Microtubules)
Moves vesicles from one place to another within the cell
Sarcomene
The smallest unit of a muscle cell that contracts
