Adv Bio Chp 6

cells

basic unit of an organism

light microscope

visible light is passed through the specimen and then through glass lenses

magnification*

the ratio of the size of an image to the size of the object

resolution*

measure of the clarity of the image

contrast*

difference in brightness between the light and dark areas of an image

organelles

membrane-enclosed structures within eukaryotic cells

electron microscope

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

scanning electron microscope (SEM)

used for detailed study of the topography of a specimen

transmission electron microscope (TEM)

used to study the internal structure of cells

biochemistry*

the study of the chemical processes (metabolism) of cells

cell fractionation

takes cells apart and separates major organelles and other subcellular structures from one another

centrifuge

spins test tubes holding mixtures of disrupted cells at a series of increasing speeds

plasma membrane

all cells bounded by this selective barrier; allows passage of enough oxygen, nutrients, and wastes

cytosol

semifluid, jellylike substance in which subcellular components are suspended

chromosomes

carry genes in the form of DNA

robosomes

tiny complexes that make proteins according to instructions from the genes

eukaryotic cell

cell with a membrane-enclosed nucleus and membrane-enclosed organelles

prokaryotic cell

cell that lacks a membrane-enclosed nucleus and membrane-enclosed organelle

nucleoid

DNA that is not membrane-enclosed

nucleus

DNA that is bounded by a double membrane; contains most of the genes in the eukaryotic cell

cytoplasm

region between the nucleus and the plasma membrane

microvilli*

long, thin projections from surface

nuclear envelope

encloses the nucleus, separating its contents from the cytoplasm

nuclear lamina

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

nuclear matrix*

framework of protein fibers extending throughout the nuclear interior

chromatin

DNA and proteins making up chromosomes

nucleolus

specialized structure in the nucleus, consisting a chromosomal regions containing ribosomal RNA genes along with ribosomal proteins imported from the cytoplasm

ribosomes

complexes made of ribosomal RNA and protein, carry out protein synthesis

free ribosomes*

suspended in they cytosol

bound ribosomes*

attached to the outside of the endoplasmic reticulum or nuclear envelope

endomembrane system

collection of membranes inside and surrounding a eukaryotic cell, related either through direct physical contact or by the transfer of membranous vesicles

vesicles

sacs of membrane

endoplasmic reticulum (ER)

network of membranes that accounts for more then half the total membrane in many eukaryotic cells

Smooth ER

outer surface lacks ribosomes; functions in diverse metabolic processes

Rough ER

studded with ribosomes on the outer surface of the membrane and thus appears rough

glycoproteins

proteins with carbohydrates covalently bonded to them

transport vesicles

transit from one [art of the cell to another

golgi apparatus

warehouse for receiving, sorting, shipping, and some manufacturing

lysosome

membranous sac of hydrolytic enzymes that make eukaryotic cells use to digest macromolecules

phagocytosis

engulf and digest microorganisms and cellular debris; amoeba

vacuoles

large vesicles derived from the endoplasmic reticulum and Golgi apparatus

food vacuoles

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

contractile vacuoles

pump excess water out of the cell, maintains suitable concentration of ions and molecules inside the cell

central vacuole

develops by coalescence of smaller vacuoles; contains sap; plays major role in growth of plant cells; absorbs water

mitochondria

sites of cellular respiration, metabolic process that uses oxygen to drive the generation of ATP by extracting energy from sugars, fats, and other fuels

chloroplasts

in plants and algae, sites of photosynthesis; converts solar energy to chemical by absorbing sunlight

endosymbiont theory

early ancestor or eukaryotic cells engulfed an oxygen-using non-photosynthesis prokaryotic cell

endosymbiont*

cell living within another cell

cristae

inner folding in the membrane of a mitochondrion

mitochondrial matrix

contains many enzymes as well as mitochondrial DNA and ribosomes; enclosed by inner membrane

thylakoids

membranous system in the form of flattened, interconnected sacs

granum

stacks of thylakoids

stroma

fluid outside the thylakoids; contains the chloroplast DNA and ribosomes as well as many enzymes

plastids

one of a family of closely related organelles that include chloroplasts, chromoplasts, and amyloplasts; found in cells of photosynthetic eukaryotes

amyloplast*

colorless organelle that stores starch (amylose)

chromoplast*

has pigments that give fruits and flowers orange and yellow hues

peroxisome

specialized metabolic compartment bounded by a single membrane; contain enzymes that remove hydrogen atoms from various substrates and transfer them to oxygen

cytoskeleton

network of fibers extending throughout the cytoplasm; gives support to the cell and maintain its shape

cell motility*

changes in cell location and movements of cell parts

motor proteins

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

microtubules

thickest fibers in the cytoskeleton; hollow rods constructed from a globular protein, tublin

microfilaments

actin filaments; thinnest fibers in the cytoskeleton; thin solid rods; built from actin

intermediate filaments

middle range of fibers in the cytoskeleton; found in some animals; specialized for bearing tension

dimeter*

made up of two subunits

centrosome

located near the nucleus; microtubules grow up from _____

centrioles

within the centrosome

cilia and flagella

microtubule-containing extensions that project from some cells

badal body

anchors microtubule in the cell

actin

globular protein

dyneins

attached along each outer microtubule; "walk" along microtubule

cortical microfilaments*

help support the cell's shape

cortex

cytoplasmic layer of a cell; semisolid consistency of a gel

myosin

protein in muscle

pseudopodia

cellular extensions to move cell forward

cytoplasmic streaming

circular flow of cytoplasm within cells

cell wall

extracellular structure of plant cells

primary cell wall

young plant secretes a thin and flexible wall called _____

middle lamella

thin layer rich in sticky polysaccharides (pectins); glues adjacent cells together

secondary cell wall

between the plasma membrane and the primary wall; deposited in several laminated layers; has strong and durable matrix that affords cell protection and support

extracellular matrix (ECM)

meshwork surrounding animal cells, consisting of glycoproteins, polysaccharides, and proteoglycans synthesized and secreted by cells

collagen

forms strong fibers outside the cells

proteoglycans

large molecule with small core protein with many carbohydrate chains attached, found in extracellular matrix of animal cells

fibronectin

extracellular glycoprotein secreted by animal cells that helps them attach to the extracellular matrix

integrins

transmembrane receptor proteins with two subunits that interconnects the extracellular matrix and the cytoskeleton

plasmodesmata

channels that connect cells