AP Biology Chapter 7 (A tour of the Cell- written by Campbell)

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Cell organelles and functions

Magnification

the ratio of an object's image to its real size

Resolving power

A measure of the clarity of the image; it is the minimum distance two points can be separated and still be distinguished as two separate points

Light microscopes (LMs)

Microscopes that use visible light to pass through the specimen and through glass lenses

Electron microscope

A microscope that instead of using light, focuses a beam of electrons through the specimen or on its surface

Scanning electron microscope (SEM)

an electron microscope commonly used for detailed study of the surface of the specimen

Transmission electron microscope (TEM)

an electron microscope commonly used to study the internal ultrastructure of cells

Cell fractionation

Goal to take cells apart; Uses a centrifuge that spins like a merry-go-round at various speeds

Cytoplasm

The entire region between the nucleus and the plasma membrane

Cytosol

A semifluid substance within the membrane of cells; where organelles are found

Nucleoid

Where the DNA is concentrated in the prokaryotic cell; no membrane separates this region from the rest of the cell

Plasma membrane

at the boundary of every cell, functions as a selective barrier; made of phospholipids and proteins

Nucleus

contains the chromatin, nucleolus, and nuclear envelope; contains most of the genes in the eukaryotic cell

Nuclear envelope

a double membrane enclosing the nucleus; perforated by pores

Chromatin

Within the nucleus; a fibrous material made of DNA and proteins

Chromosome

Chromatin fibers that coiled up, becoming thick enough to be discerned as separate structures; occurs when cell prepares to divide

nucleolus

a prominent structure within the nucleus; Ribosomal RNA is snthesized

Ribosome

particles made of ribosomal RNA and protein; the organelles that carry out protein synthesis (free/bound)

Endomembrane system

all the different membranes of the eukaryotic cell

vesicles

sacs made of membrane; transfer of membrane segments

Endoplasmic Reticulum (ER)

consists of a network of membranous tubules and sac; continuous with the nuclear envelope (smooth/rough)

Smooth ER

part of the ER where the cytoplasmic surface lacks ribosomes

Rough ER

part of the ER where cytoplasmic surface appears rough due to ribosomes attached

centrioles

structure in animal cells composed of cylinders of microtubule triplets; a pair involved in animal celll division

Golgi Apparatus

A center of manufacturing, warehousing, sorting, and shipping; modifies the products of the ER

Cis face

the "receiving" side of the golgi apparatus; closer to the ER

Trans face

the "shipping" side of the golgi apparatus; further away from the ER

Lysosome

a membrane-bound sac of hydrolytic enzymes that the cell uses to digest macromolecules

Phagocytosis

A process that describes Amoebas/Protists eating by engulfing smaller organisms or other food particles

Vacuoles/Vesicles

membrane-bound sacs within the cell (vacuoles larger than vesicles)

Food Vacuoles

formed by phacogytosis; pinches off of the plasma membrane and encloses a food particle

Contractile vacuoles

pumps excess water out of the cell (in many freshwater protists)

Central vacuole

The largest compartment in the plant cell; functions include storage, waste disposal, protection, and growth

Tonoplast

encloses the central vacuole; part of the endomembrane system

Peroxisome

a microbody containing enzymes that transfer hydrogen from various substrates to oxygen; produces hydrogen peroxide

Mitochondria

sites of cellular respiration (catabolic process that generates ATP); uses oxygen

intermembrane space

The narrow region between the inner and outer membranes of mitochondria

plastids

a family of closely related plant organelles (includes chloroplasts)

chloroplasts

sites of photosynthesis; found only in plants and algae

thylakoids

a membranous system in the form of flattened sacs inside of the chloroplasts

thylakoid space

the compartment within the stroma; contains the grana

granum

a stack of thylakoids (piled like poker chips)

stroma

the fluid outside of the thylakoids; cotains the chloroplast DNA, ribosomes, and enzymes

cytoskeleton

a network of fibers extending throughout the cytoplasm; gives the cell mechanical support, maintains shape, provides anchorage for organelles, motility

microtubules

the thickest of the three types of fibers that make up cytoskeleton; eukaryotic cells; hollow tube made from tubulin

microfilaments

the thinnest of the three types of fibers in cytoskeleton; two intertwined stands of actin

intermediate filaments

fibers with diameters in a middle range that make up cytoskeleton; fibrous proteins suercoiled into thicker cables

centrosome

a region near the nucleus where microtubules grow out from

cilia

locomotor appendages; usually occur in large numbers, have a back-and-forth motion

flagella

locomotor appendages; has an undulating motion

tubulin

a globular protein; constructs microtubules

dynein

a large contractile protein forming the side-arms of microtubule doublets in cilia and flagella

actin

a globular protein that links into chains, two of which twist helically about each other, forming microfilaments in muscle and other contractile elements in cells

myosin

a type of protein filament that interacts with actin filaments to cause cell contraction

plasmodesmata

porous holes between the plant cells; lets the cytoplasm become continous between the cells

cell wall

prevents the cell from bursting (not in animal cells)

primary cell wall

a relatively thin and flexible cell well secreted by young plant cells

secondary cell wall

a strong durable matrix often deposited in several laminated layers for plant cell protection and support

Extracellular Matrix

The substance in which animal tissue cells are embedded, consisting of protein and polysaccharides.

collagen

A glycoprotein in the extracellular matrix of animal cells that forms strong fibers, found extensively in connective tissue and bone; the most abundant protein in the animal kingdom.

Proteoglycan

A glycoprotein 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

a glycoprotein that helps animal cells attach to the extracellular matrix.

integrin

A receptor protein built into the plasma membrane that interconnects the extracellular matrix and the cytoskeleton.

plasmodesmata

Open channels in the cell wall of a plant through which strands of cytosol connect from an adjacent cell.

desmosomes

specialized junctions that hold adjacent cell together, consist of dense plate at point of adhesion plus extracellular cementing material

tight junctions

Membranes of neighboring cells are pressed together, preventing leakage of extracellular fluid

gap junctions

Points that provide cytoplasmic channels from one cell to another with special membrane proteins. Also called communicating junctions.

basal body

a structure resembling a centriole that produces a cilium or flagellum and anchors this structure within the plasma membrane

motor molecule

protein that moves along either actin filaments or microtubules and translocates organelles

amyoplast

colorless plastids that store starch

macrophages

A type of white blood cell that engulfs microbes and destroys them by phagocytosis; also presents microbial antigens to T cells, helping stimulate the immune response

nucleolar organizer

a unique region (usually on one specific chromosome) that contains multiple repeats of genes encoding ribosomal RNA

cytoplasmic streaming

A circular flow of cytoplasm, involving myosin and actin filaments, that speeds the distribution of materials within cells.

chromoplast

plastids responsible for pigment synthesis and storage such as orange carotene, yellow xanthophylls and various other red pigments

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