CH. 3 Cell Structure and Function

mitochondria

(singular,mitochondrion) the cellular organelles responsible for carrying out cellular respiration,resulting in the production of ATP,the cell's main energy-carrying molecule

eukaryotic cell

a cell that has a membrane-bound nucleus and several other membrane-bound compartments or sacs

ribosome

a cellular organelle that carries out protein synthesis

gap junction

a channel between two adjacent animal cells that allows ions,nutrients,and other low-molecular weight substances to pass between the cells,enabling the cells to communicate

plasmodesma (plural ,plasmodesmata)

a channel that passes between the cell walls of adjacent plant cells,connects their cytoplasm,and allows materials to be transported from cell to cell

Golgi apparatus

a eukaryotic organelle made up of a seriesof stacked membranes that sorts,tags,and packages lipids and proteins for distribution

tight junction

a firm seal between two adjacent animal cells created by protein adherence

electrochemical gradient

a gradient produced by the combined forces of the electrical gradient and the chemical gradient

central vacuole

a large plant cell organelle that acts as a storage compartment,water reservoir,and site of macromolecule degradation

desmosome

a linkage between adjacent epithelial cells that forms when cadherins in the plasma membrane attach to intermediate filaments

organelle

a membrane-bound compartment or sac within a cell

vacuole

a membrane-bound sac,somewhat larger than a vesicle,that functions in cellular storage and transport

passive transport

a method of transporting material that does not require energy

fluid mosaic model

a model of the structure of the plasma membrane as a mosaic of components,including phospholipids,cholesterol,proteins,and glycolipids,resulting in a fluid rather than static character

diffusion

a passive process of transport of low-molecular weight material down its concentration gradient

plasma membrane

a phospholipid bilayer with embedded (integral) or attached (peripheral) proteins that separates the internal contents of the cell from its surrounding environment

chloroplast

a plant cell organelle that carries out photosynthesis

facilitated transport

a process by which material moves down a concentration gradient (from high to low concentration) using integral membrane proteins

exocytosis

a process of passing material out of a cell

phagocytosis

a process that takes macromolecules that the cell needs from the extracellular fluid; a variation of endocytosis

pinocytosis

a process that takes solutes that the cell needs from the extracellular fluid; a variation of endocytosis

cell wall

a rigid cell covering made of cellulose in plants,peptidoglycan in bacteria, non-peptidoglycan compounds in Archaea,and chitin in fungi that protects the cell,provides structural support,and gives shape to the cell

endoplasmic reticulum (ER)

a series of interconnected membranous structures within eukaryotic cells that collectively modify proteins and synthesize lipids

cilium (plural,cilia)

a short,hair-like structure that extends from the plasma membrane in large numbers and is used to move an entire cell or move substances along the outer surface of the cell

vesicle

a small,membrane-bound sac that functions in cellular storage and transport; its membrane is capable of fusing with the plasma membrane and the membranes of the endoplasmic reticulum and Golgi apparatus

peroxisome

a small,round organelle that contains hydrogen peroxide,oxidizes fatty acids and amino acids,and detoxifies many poisons

solute

a substance dissolved in another to form a solution

endocytosis

a type of active transport that moves substances,including fluids and particles,into a cell

prokaryotic cell

a unicellular organism that lacks a nucleus or any other membrane-bound organelle

receptor-mediated endocytosis

a variant of endocytosis that involves the use of specific binding proteins in the plasma membrane for specific molecules or particles

concentration gradient

an area of high concentration across from an area of low concentration

lysosome

an organelle in an animal cell that functions as the cell's digestive component; it breaks down proteins,polysaccharides,lipids,nucleic acids,and even worn-out organelles

hypertonic

describes a solution in which extracellular fluid has higher osmolarity than the fluidinside the cell

hypotonic

describes a solution in which extracellular fluid has lower osmolarity than the fluid inside the cell

isotonic

describes a solution in which the extracellular fluid has the same osmolarity as the fluid inside the cell

tonicity

the amount of solute in a solution

unified cell theory

the biological concept that states that all organisms are composed of one or more cells,the cell is the basic unit of life,and new cells arise from existing cells

nucleus

the cell organelle that houses the cell's DNA and directs the synthesis of ribosomes and proteins

selectively permeable

the characteristic of a membrane thatallows some substances through but not others

nucleolus

the darkly staining body within the nucleus that is responsible for assembling ribosomal subunits

nuclear envelope

the double-membrane structure that constitutes the outermost portion of the nucleus

cytoplasm

the entire region between the plasma membrane and the nuclear envelope,consisting of organelles suspended in the gel-like cytosol,the cytoskeleton,and various chemicals

cytosol

the gel-like material of the cytoplasm in which cell structures are suspended

endomembrane system

the group of organelles and membranes in eukaryotic cells that work together to modify,package,and transport lipids and proteins

microscope

the instrument that magnifies an object

flagellum (plural,flagella)

the long,hair-like structure that extends from the plasma membrane and is used to move the cell

extracellular matrix

the material,primarily collagen,glycoproteins,and proteoglycans,secreted from animal cells that holds cells together as a tissue,allows cells to communicate with each other,and provides mechanical protection and anchoring for cells in the tissue

active transport

the method of transporting material that requires energy

cytoskeleton

the network of protein fibers that collectively maintains the shape of the cell,secures some organelles in specific positions,allows cytoplasm and vesicles to move within the cell,and enables unicellular organisms to move

smooth endoplasmic reticulum (SER)

the region of the endoplasmic reticulum that has few or no ribosomes on its cytoplasmic surface and synthesizes carbohydrates,lipids,and steroid hormones; detoxifies chemicals like pesticides,preservatives,medications,and environmental pollutants,and stores calcium ions

rough endoplasmic reticulum (RER)

the region of the endoplasmic reticulum that is studded with ribosomes and engages in protein modification

osmolarity

the total amount of substances dissolved in a specific amount of solution

osmosis

the transport of water through a semipermeable membrane from an area of high water concentration to an area of low water concentration across a membrane