AP Biology - Chapter 6 & 7

light microscope (LM)

a microscope where visible light is passed through the specimen and then through glass lenses

organelles

membrane-enclosed structures within eukaryotic cells

electron microscope (EM)

a microscope that focuses a beam of electrons through the specimen or onto its surface

scanning electron microscope (SEM)

a microscope used for detailed study of the topography of a specimen

transmission electron microscope (TEM)

a microscope used to study the internal structure of cells

cell fractionation

a useful technique for studying cell structure and function which takes cells apart and separates major organelles and other subcellular structures from one another

cytosol

a semifluid, jellylike substance in which subcelluar components are suspended

eukaryotic cell

an animal, plant, protist, or fungi cell in which most of the DNA is in an organelle called the nucleus

prokaryotic cell

a bacteria cell in which the DNA is concentrated in a region that is not membrane enclosed

nucleoid

a dense region of DNA in a prokaryotic cell

cytoplasm

the interior of either type of cell

plasma membrane

the boundary of every cell, which functions as a selective barrier that allows passage of enough oxygen, nutrients, and wastes to service the entire cell

nucleus

contains most of the genes in the eukaryotic cell

nuclear envelope

encloses the nucleus, separating its contents from the cytoplasm

nuclear lamina

a netlike array of protein filaments that maintains the shape of the nucleus by mechanically supporting the nuclear envelope

nucleolus

a prominent structure within the non-dividing nucleus involved in the production of ribosomes

ribosomes

complexes made of ribosomal RNA and protein which are the cellular components that carry out protein synthesis

endomembrane system

consists of the nuclear envelope, the endoplasmic reticulum, the Golgi apparatus, lysosomes, various kinds of vesicles and vacuoles, and the plasma membrane

vesicles

membrane sacs that specialize in moving products into, out of, and within a cell

endoplasmic reticulum (ER)

an extensive network of membranes that accounts for more than half of the total membrane in many eukaryotic cells

smooth ER

the outer surface lacks ribosomes

rough ER

studded with ribosomes on the outer surface of the membrane

glycoproteins

proteins that have carbohydrates covalently bonded to them

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

lysosome

a membrane-closed sac of hydrolydic enzymes found in the cytoplasm of animal cells and some protists

phagocytosis

a type of endocytosis in which large, particulate substances or small organisms are taken up by the cell

vacuole

a membrane-bound vesicle whose specialized function varies in different kinds of cells

food vacuole

a membranous sac formed by phagocytosis of microorganisms or particles to be used as food by the cell

contractile vacuole

a membranous sac that helps move excess water out of certain freshwater protists

central vacuole

a large, membranous with diverse roles in growth, storage, and sequestration of toxic substances

mitochondrion

an organelle in eukaryotic cells that serves as the site of cellular respiration; uses oxygen to break down organic molecules and synthesize ATP

chloroplast

an organelle found in plants and photosynthetic that absorbs sunlight and uses it to drive the synthesis of organic compounds from carbon dioxide and water

endosymbiont theory

the theory that mitochondria and chloroplasts originated as prokaryotic cells engulfed by an ancestral eukaryotic cell, which became its host cell and then evolved into a single organism

crista

an infolding of the inner membrane of the mitochondrion; the inner membrane houses electron transport chains and molecules of the enzyme catalyzing the synthesis of ATP

stroma

the dense, fluid liquid within the chloroplast surrounding the thylakoid membrane and containing ribosomes and DNA; involved in the synthesis of organic molecules from carbon dioxide and water

peroxisome

an organelle containing enzymes that transfer hydrogen atoms from various substrates to oxygen, producing and then degrading hydrogen peroxide

cytoskeleton

a network of microtubules, mircofilaments, and intermediate filaments that extend throughout the cytoplasm and serve a variety of mechanical, transport, and signal functions

motor protein

a protein that interacts with cytoskeletal elements and other cell components, producing movement of the whole cell or parts of the cell

flagellum

a long cellular appendage specializing in locomotion

cortex

The outer region of cytoplasm, that has a more gel-like consistency than the inner regions due to the presence of multiple microfilaments

cell wall

A protective layer external to the plasma membrane in the cells of plants, prokaryotes, fungi, and some protists; cellulose is an important structural component of cell walls

collagen

a glycoprotein in the extracellular matrix of animal cells that forms strong fibers, found in connective tissue and bone; the most abundant protein in animals

selective permeability

a property of biological membranes that allows them to regulate the passage of substances across them

amphipathic

having both a hydrophilic region and a hydrophobic region

fluid mosaic model

the currently accepted model of cell membrane structure, which envisions the membrane as a mosaic of protein molecules drifting laterally in a fluid bilayer of phospholipids

integral protein

a transmembrane protein with hydrophobic regions that extend into hydrophobic interior of the membrane and with hydrophilic regions in contact with the aqueous solution on one or both sides of the membrane

peripheral protein

a protein loosely bound to the surface of a membrane or to part of an integral protein and not embedded in the lipid bilayer

glycolipid

a lipid with one or more covalently attached carbohydrates

glycoprotein

a protein with one or more covalently attached carbohydrates

transport protein

a transmembrane protein that helps a certain substance or class of closely related substances to cross the membrane

aquaporin

a channel protein in the plasma membrane of a cell that specifically facilitates osmosis, the diffusion of free water across the membrane

diffusion

the spontaneous movement of a substance down its concentration l gradient, from a region where it is more concentrated to a region where it is less concentrated

concentration gradient

a region along which the density of a chemical substance increases or decreases

passive transport

the diffusion of a substance across a biological membrane with no expenditure of energy

osmosis

the diffusion of free water across a selectively permeable membrane

tonicity

the ability of a solution surrounding a cell to cause that cell to gain or lose water

isotonic

refers to a solution that, when surrounding a cell, causes no net movement of water into or out of the cell

hypertonic

refers to a solution that, when surrounding a cell, will cause the cell to lose water

hypotonic

referring to a solution that, when surrounding a cell, will cause the cell to take up water

osmoregulation

regulation of solute concentrations and water balance by a cell or organism

facilitated diffusion

the passage of molecules or ions down their electrochemical gradient across a biological membrane with the assistance of specific transmembrane transport proteins, requiring no energy expenditure

ion channel

a transmembrane protein channel that allows a specific ion to diffuse across the membrane down its concentration or electrochemical gradient

gated channel

a transmembrane protein channel that opens or closes in response to a particular stimulus

active transport

the movement of a substance across a cell membrane against its concentration gradient, mediated by specific transport proteins and requiring an expenditure of energy

sodium-potassium pump

a transport protein in the plasma membrane of animal cells that actively transports sodium out of the cell and potassium into the cell

membrane potential

the difference in voltage across a cell's plasma membrane due to the differential distribution of ions; membrane potential affects the activity of excitable cells and the transmembrane movement of all charged substances

electrochemical gradient

the diffusion gradient of an ion, which is affected by both the concentration difference of an ion across a membrane and the ion's tendency to move relative to the membrane potential

electrogenic pump

an active transport protein that generates voltage across a membrane while pumping ions

proton pump

an active transport protein in a cell membrane that uses ATP to transport hydrogen ions out of a cell against their concentration gradient, generating a membrane potential in the process

exocytosis

the cellular secretion of biological molecules by the fusion of vesicles containing them with the plasma membrane

endocytosis

cellular uptake of biological molecules and particulate matter via formation of vesicles from the plasma membrane