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light microscope

visible light is passed through the specimen and then through glass lenses which light is refracted in such a way that the image of the specimen is magnified as it is projected; types: bright field, phase-contrast, fluorescence, confocal

organelles

membrane-enclosed structures within eukaryotic cells

electron microscope

focuses a beam of electrons through the specimen or onto its surface; hundredfold improvement over standard light microscope; SEM and TEM

scanning electron microscope (SEM)

used for detailed study of the topography of a specimen; creates 3D image of cells

transmission electron microscope (TEM)

used to study the internal structure of cells; specimen stained;

cell fractionation

a centrifuge is used to take cells apart and separate major organelles and other sub cellular structures from one another; process is by spinning the test tubes at high speeds

prokaryotic cells

lack a true nucleus and other membrane-enclosed organelles of the eukaryotic cell; much simpler in structure; include bacteria and archaea;

eukaryotic cells

protists, fungi, animals and plants are composed of eukaryotic cells; most DNA is contained in the double membrane bound nucleus

cell components

all cells are bounded by the plasma membrane, have cytosol, chromosomes, and ribosomes

cytosol

inside all cells there is a semifluid, jellylike substance called cytosol in which subcelluar components are suspended

cytoplasm

in eukaryotic cells, this term refers only to the region between the nucleus and the plasma membrane

plasma membrane

selective barrier that allows passage of enough oxygen, nutrients and wastes to service the entire cell

cytoskeleton

reinforces cells shape; functions in cell movement; components are made of protein. includes microfilaments, intermediate filaments, microtubules

ribosomes

complexes that make proteins; free in cytosol or bound to rough ER or nuclear envelope

golgi apparatus

organelle active in synthesis, modification, sorting, and secretion of cell products

peroxisome

organelle with various specialized metabolic functions; produces hydrogen peroxide as a by-product, then converts it to water

mitochondrion

organelle where cellular respiration occurs and most ATP is generated

centrosome

region located near the nucleus where the cells microtubules are initiated; contains a pair of centrioles

flagellum

motility structure present in some animal cells, composed of a cluster of microtubules within an extension of the plasma membrane

endoplasmic reticulum

network of membranous sacs and tubes; active in membrane synthesis and other synthetic and metabolic processes; composed of rough er and smooth er

nucleus

composed of: nuclear envelope, nucleolus and chromatin; contain most of genes(DNA) in eukaryotic cell

nuclear envelope

double membrane enclosing the nucleus; perforated by pores; continuous with ER

nuclear lamina

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

nucleolus

nonmembranous structure involved in production of ribosomes; a nucleus has one or more nucleoli; synthesizes rRNA from instructions in DNA

chromosome

structures of DNA that carry the genetic information

chromatin

material consisting of DNA and proteins; visible in a dividing cell as individual condensed chromosomes

in animal but not plant cells

lysosomes, centrosomes with centrioles, and flagella

in plant but not animal cells

chloroplasts, central vacuole, cell wall and plasmodesmata

cell wall

outer layer that maintains cells shape and protects cell from mechanical damage; made of cellulose, other polysaccharides and protein

plasmodesmata

cytoplasmic channels through cell walls that connect the cytoplasms of adjacent cells

chloroplast

photosynthetic organelle; converts energy of sunlight to chemical energy stored in sugar molecules

endomembrane system

composed of: nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, various kinds of vesicles and vacuoles and plasma membrane; membranes of this system are related either through direct physical continuity or by the transfer of membrane segments as tiny vesicles

functions of endomembrane system

synthesis of proteins, transport of proteins into membranes and organelles or out of the cell, metabolism and movement of lipids, and detoxification of poisons

smooth ER

enzymes of smooth ER are important in the synthesis of lipids, detoxify drugs and poisons(esp. in liver cells), stores calcium ions

rough ER

studded with ribosomes; membrane factory for the cell; makes membrane phospholipids

glycoproteins

proteins that have carbohydrates covalently bonded to them

transport vesicles

vesicles in transit from one part of the cell to another

golgi apparatus

"warehouse" for receiving, sorting, shipping, and even some manufacturing; consist of stacks of flattened sacs (cisternae) not physically connected

"cis" face of golgi apparatus

"receiving department" of golgi. located near ER

"trans" face of golgi apparatus

"dispatches vesicles"; gives rise to vesicles that pinch off and travel to other sites

lysosome

digestive organelle where macromolecules are hydrolyzed; digest materials taken into the cell

phagocytosis

carried out by lysosomes: engulfing smaller organisms or food particles; macrophages (white blood cells that engulfs and destroy bacteria)

food vacuoles

formed by phagocytosis

contractile vacuoles

pump excess water out of the cell, thereby maintaining a suitable concentration of ions and molecules inside the cell

central vacuole

develops by the coalescence of smaller vacuoles; plays a major role in growth of cells by enabling the cell to become larger with a minimal investment in new cytoplasm

mitochondria

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

chloroplasts

membranes divide space into 3 compartments: inter membrane space, stroma and thylakoid space. found in plants and algae; sites of photosynthesis; convert solar energy to chemical energy by absorbing sunlight and using it to drive the synthesis of organic compounds such as sugars from carbon dioxide and water

endosymbiont theory

theory states that an early ancestor of eukaryotic cells engulfed an oxygen-using non photosynthetic prokaryotic cell. eventually, the engulfed cell formed a relationship with the host cell in which it was enclosed, becoming an endosymbiont; over the course of evolution, the host cell and its endosymbiont merged into a single organism, a eukaryotic cell with a mitochondrion

cristae

foldings in mitochondrion

mitrochrondrial matrix

enclosed by the inner membrane

thylakoids

in chloroplasts; membranous system in the form of flattened, interconnected sacs

granum

stacks of thylakoids

stroma

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

plastids

family of closely related plant organelles; amyloplast: a colorless organelle that stores starch(amylose), particularly in roots and tubers; another is the chromoplast, which has pigments that give fruits and flowers their orange and yellow hues

peroxisome

a specialized metabolic compartment bounded by a single membrane; contain enzymes that removes hydrogen atoms from various substrates and transfer them to oxygen producing hydrogen peroxide as a by-product.

cytoskeleton

network of fibers extending throughout the cytoplasm; composed of 3 types of molecular structures: microtubules, microfilaments, and intermediate filaments

microtubules

hollow tubes; functions: maintenance of cell shape, guide organelle movement, and separate chromosomes in dividing cells

microfilaments

two intertwined strands of actin; functions: maintenance of cell shape, changes in cell shape, muscle contraction, cytoplasmic streaming, cell motility, and cell division

intermediate filaments

fibrous proteins supercoiled into thicker cables; functions: maintenance of cell shape, anchorage of nucleus and certain other organelles, and formation of nuclear lamina

centrioles

9 sets of pairs of centrioles located within centrosome

basal body

structurally similar to a centriole; anchors a microtubule assembly of a cilium or flagellum

dyneins

In cilia and flagella, a large motor protein extending from one microtubule doublet to the adjacent doublet. ATP hydrolysis drives changes in dynein shape that lead to bending of cilia and flagella.

actin

a globular protein

cortex

outer cytoplasmic layer of a cell semisolid consistency

myosin

A type of motor protein that associates into filaments that interact with actin filaments to cause cell contraction.

cytoplasmic streaming

a circular flow of cytoplasm within cells that speeds the distribution of materials within the cell

primary cell well

a young plant first secretes a realtively thin and flexible wall

middle lamella

a thin layer rich in sticky polysaccharides called pectins

secondary cell wall

between plasma membrane and primary cell wall; has a strong and durable matrix that affords the cell protection and support

extracellular matrix (ECM)

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

collagen

forms strong fibers outside cells; accounts for 40% of total protein in human body

proteoglycans

A large molecule consisting of a small core protein with many carbohydrate chains attached, found in the extracellular matrix of animal cells. A proteoglycan may consist of up to 95% carbohydrate.

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.

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.

tight junctions

prevent fluid from moving across a layer of cells

desmosomes

"anchoring junctions" function like rivets, fastening ells together in strong sheets. attach muscle cells to each other in a muscle.

gap junctions

"communicating junctions" provide cytoplasmic channels from one cell to an adjacent cell; necessary for cell communication

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