biology exam 2

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

• -most common microscope in the lab
• -visible light is passed through the specimen and then through the glass lenses

measure of the clarity of the image

• magnification 100,000x
• electron beam in a vaccum focused by magnets
• electron beam has much shorter wavelength than visible light

• provides for detailed studies of the surface of a specimen
• thing getting studied often covered in gold

study of intermal ultrastructure of cells

• uses centrifuge
• takes cells apart and separates the major organelles and other subcellular structures from one another
• forms pellets on the bottom
• most dense pellet out first

selective barrier that bounds and protects all cells

Mitochondria

mitochondria

chloroplasts

• plant cell
• photosynthetic organelle
• converts energy of sunlight to chemical energy stored in sugar molecules

• plant cells
• channels through cell walls that connect the cytoplasms of adjacent cells

• plant cells
• prominent organelle in older plant cells
• functions include storage, breakdown of waste products, hydrolysis of macromolecules
• enlargement of vacuole is a major mechanism of plant growth

• membranous sac that animal uses to digest molecules
• acidic environment
• recycles cell's organic molecules

• plant and animal cells
• organelle where cellular respiration occurs and ATP is generated

• plant and animal cells
• products of ER are modified and stored and then sent to other destinations
• consist of cisternae-flattened membranous sacs resembling stacks of pita bread
• two poles of stack are called cis face and trans face

• animal cell
• locomotion organelle present in some animal cells
• composed of a cluster of microtubules within an extension of the plasma membrane

a type of intercellular junction in animals that allows the passage of materials between cells

accentuates differences in parts of the sample

• complexes made of ribosomal RNA and protein
• carry out protein synthesis
• free or bound

nuclear envelope, endoplasmic reticulum, Golgi apparatus, lysosomes, vacuoles, and the plasma membrane

• network of membranous tubules and sacs called cisternae
• separates internal compartment of the ER from the cytosol
• smooth and rough

• metabolic processes: synthesis of lipids, metabolism of carbs, detox of drugs and poisons
• stores calcium ions

• makes secretory proteins
• grows in place by adding membrane proteins and phospholipids to its own membrane
• have ribosomes attached

flattened, interconnected sacs in the chloroplast

individual stack of thylakoids

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

• network of fibers extending throughout the cytoplasm
• made up of microtubules, microfilaments, and intermediate filaments
• support, mobility, and regulation

• thickest of the three components of the cytoskeleton
• wall of this tube is filled with tubulin
• shape and support the cell
• serve as tracks along which organelles equipped with motor proteins can move
• can separate chromosomes during cell division

• built from molecules of actin
• present in all eukaryotic cells
• cell motility

• more permanent fixtures of cells than microfilaments and microtubules
• functions as the framework of the entire cytoskeleton

• extracellular structure of plant cell
• protects plant cell, maintains its shape, and prevents excessive uptake of water

• hydrophilic region and hydrophobic region
• most proteins within membranes are amphipathic

the membrane is a fluid structure with a "mosaic" of various proteins embedded in or attached to a bilayer of phospholipids

fasten cells together into strong sheets

• plasma membrane of neighboring cells are very tightly pressed against each other, bound together by specific proteins
• prevent leakage of extracellular fluid across a layer of epithelial cells

Phospholipids

Integral and peripheral

penetrate hydrophobic core of lipid bilayer

appendages lossely bound to the surface of the membrane, often exposed to parts of integral proteins

hydrophobic channel that certain molecules or atomic ions use as a tunnel through the membrane

• movement of molecules of any substance so that they spread out evenly into the available space
• more concentration to less concentration

• diffusion of a substance across a biological membrane
• cell doesnt have to expend energy ot make it happen

diffusion of water across a selectively permeable membrane

the ability of a solution to cause a cell to gain or lose water

• same environment for the cell and its environment
• no net movement of water acorss the plasma membrane
• water flows at the same rate in both directions
• volume of cell is stable

• water will lose water to environment
• shrivel and die

• water will enter cell faster than it leaves
• cell will swell and burst

swollen or distended as in plant cells (A walled cell becomes turgid if it has a greater solute concentration than its surroundings, resulting in entry of water)

• limp
• plant cell becomes flaccid when the cells and surroundings are isotonic
• no tendency for water to enter

the spontaneous passage of molecules or ions across a biological membrane with the assistance of specific transmembrane transport proteins

• channel proteins
• carrier proteins

provide corridors that allow a specific molecule or ion to cross the membrane