Export Campbell Biology Chapter 6

cell fractionation

technique that breaks cells and separates their components by serial centrifugation

cytoplasm

aqueous interior of the cell within which particles and organelles are suspended

nucleoid

densly staining DNA region in a prokaryotic cell

chromatin

protein and DNA complex

chromosome

single molecule of DNA; contains hereditary information

nucleus

organelle that contains DNA and controls processes of cell

nucleolus

organelle where ribosomes are synthesized and partially assembled (within nucleus)

nuclear envelope

perforated double membrane that controls flow of materials (around nucleus)

ribosomes

organelles made of protein and rRNA that direct protein synthesis (in cytoplasm or tethered to rough ER)

nuclear lamina

netlike array of intermediate filaments that protects and maintains shape of nucleus

endoplasmic reticulum (ER)

internal membrane system in which components of cell membrane and some proteins are constructed

rough ER

organelle continuoues with nuclear membrane, to which ribosomes are tethered and proteins are synthesized for export

smooth ER

organelle where lipids are synthesized

vesicles

small sacs surrounded by phospholipid bilayer that specialize in moving products into, out of, and within a cell

golgi apparatus

stack of membranes that modifies, sorts, and packages proteins for transport

lysosome

organelle filled with enzymes that break down chemicals

phagocytosis

when extensions of cytoplasm surround and engulf large food particles

central vacuole

membranous sac in plant cells with roles in reproduction, growth, and storage

mitochondria

organelle in all eukaryotic cells where chemical energy in glucose and fats is transformed into ATP (cellular respiration SITE)

chloroplast

organelle in plants where sunlight energy is used to synthesize glucose (photosynthesis SITE)

endosymbiont theory

states that mitochondria and chloroplasts originated as prokaryotic cells engulfed by ancestral eukaryotic cell

mitochondrial matrix

innermost compartment of the mitochondria; Krebs cycle occurs here

cristae

inner membrane infoldinfgs of mitochondria that increase surface area (Electron Transport Chain and ATP synthase are located here)

thylakoids

flattened membrane sacs in chloroplast (contains proteins for light-dependent reactions in photosynthesis)

grana

stacked thylakoid membranes in chloroplast

stroma

innermost compartment of chloroplast (Calvin cycle or light-independent reactions occur here)

peroxisomes

animal orgnalles that contain enzymes that detoxify alcohols, hydrogen peroxide, and other harmful chemicals

cytoskeleton

microscopic network of protein fibers within cytoplasm that gives shape to cell

microtubules

(bottom) thickest, hollow tubes of tubulin proteins that make up cilia, flagella, and mitotic spindle and help move organelles around cell

microfilaments

(top) thinnest, intertwined fibers of actin proteins that allow cytoplasmic streaming, ameboid movement and keep cell extensions rigid (microvilli, axons)

intermediate filaments

(middle) medium, coiled fibers of keratin that help maintain cell shape, stabilize positions of organelles

centrioles

organelles in animal cells from which mitotic spindle forms during cell division (resemble basal bodies)

mitotic spindle

microtubules that attach to centromeres through kinetochore proteins of chromosomes and pull sister chromatids apart during cell divisions

cilia

(A) short, many extensions of membrane-covered microtubules that move cell or materials past cell (ex. paramecium, trachea)

flagella

(E) long, few, whiplike tails of membrane-covered microtubules that move cells

cytoplasmic streaming

circular flow of cytosol using myosin and actin filaments that speeds up distribution of materials within cells

cell wall

strong supporting layer around the cell membrane. Composed of peptidoglycan (prokaryotes), chitin (fungi) or cellulose (plants)

extracellular matrix (ECM)

substance in which animal cells are embedded, consisting of proteins and polysaccharides

plasmodesmata

(2) openings in plant cell walls through which strands of ER and cytosol connect adjacent cells

gap junctions

(C) cytoplasmic channels between adjacent animal cells that allow movement of materials

tight junctions

(A) membrane fusions of neighboring cells that prevent leakage of fluid between them

adhering junctions

(B) anchoring junctions that prevents cells subjected to mechanical stress from being pulled apart

prokaryote

unicellular organism without nucleus and membrane bound organelles (archea and bacteria)

eukaryote

cells with nucleus and membrane bound organelles

psuedopodia

temporary projections of eukaryotic cell membranes or unicellular protists in direction of movement

collagen

fibrous protein found in connective tissues and ECM