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Cells: Structure and Function (Cell Organelles (Nucleus (Nuclear Envelope,…
Cells: Structure and Function
Types of Microscopes
Light Microscope
an optical instrument with lenses that refract visible light to magnify images of specimen
Electron Microscope
A microscope that uses magnets to focus an electron beam on or through a specimen
electron microscope is used to study the fine details of cell surfaces
Scanning Electron microscope
a microscope that uses an electron beam to scan the surface of a sample coated with a metal atom to study details of topography
Transmission Electron Microscope
a microscope that passes electron beam through very thin sections stained with metal atoms and is primarily used to study the internal structure of cells
Cell Organelles
Nucleus
contains the genetic material in the form of chromosomes made up of chromatin
Nuclear Envelope
encloses the nucleus separating its contents from the cytoplasm
Nuclear Lamina
a netlike array of protein filaments that maintain the shape of the nucleus by mechanically supporting the nuclear envelope
Chromosomes
composed of structures that carry genetic information into the cell
each chromosome contains one long DNA molecule associated with many proteins
Chromatin
The complex of DNA and proteins making up chromosomes
Nuclelus
prominent structure that appears through the electron microscope as a mass of densely stained granules and fibers adjoining the chromatin
Ribosomes
which are complexes made of ribosomal RNAs and proteins
consist of cellular components that carry out protein synthesis
Build proteins in two cytoplasmic locales
Free ribosomes are suspended in the cytosol while bound ribosomes are attached outside of the endoplasmic reticulum or nuclear envelope
Endoplamic Reticulum
extensive network of membranes that account for more than half of the total membrane in eukaryotic cells
Smooth ER
outer surface lacks ribosomes
functions in diverse metabolic processes: synthesis of lipids, metabolism of carbohydrates, detoxification of drugs and poison, and storage of calcium ions.
Rough ER
studied with ribosomes on the outer surface of the membrane and thus appear rough through the electron microscope
secrete proteins that are produced by ribosomes attached to rough ER
Golgi Apparatus
receives, sorts, ships, and even manufactures proteins
consist of a group of associated flatened membranous sacs-cisternae looking like stacks of pita bread
Lylsosome
is a membranous sac of hydrolytic enzymes that many eukaryotic cells use to digest macromolecules
work best in acidic environments found in lysosomes
carry out intracellular digestion in a variety of circumstances
Vacuoles
large vesicles derived from the endoplasmic reticulum and golgi apparatus
Contractile Vacuoles
pump excess water out of the cell maintaining a suitable concentration of ions and molecules inside the cell
Food Vacuoles
a vacuole with a digestive function in the protoplasm of a protozoan
Central Vacuole
develops coalescence of smaller vacuoles
Mitochondria
are the sites of cellular respiration, the metabolic process that uses oxygen to drive the generation of ATP by extracting the energy from sugars, fats, and other fuels.
Chloroplast
found in plants and algae: are the 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
MIcrotubules
hollow rods constructed from globular proteins called tubulins
Animals: grow out from the centrosome
MIcrofilaments
solid thin rods that are built from molecules of actin a globular protein
Intermediate Filaments
larger in diameter of microfilaments but smaller than that of microtubules: are only found in vertebrates
Peroxisome
specialized metabolic compartments bounded by a single membrane
contains enzymes that transfer H atoms from substrates to oxygen producing H2O2 which is then converted to H2O
Selective Permeability
the ability to regulate transport across cellular boundaries; a function essential to the cells existence
Permeability of a lipid-bilayer
consist of nonpolar molecules such as hydrocarbons
Transport Proteins
hydrophilic substances that can avoid contact with the lipid bilayer
span the membrane
Also called channel proteins
function by having a hydrophilic channel that certain molecules or atomic ions use as a tunnel through the membrane
Aquaporins
the passage of water molecules through the membrane in certain cells that is greatly facilitated by channel proteins
each aquaporin allows entry of up to 3 billion water molecules per second passing single file through its central channel
Passive Transport
Diffusion
the movement of particles of any substance so that they spread out into the available space
Concentration Gradient
the region along which the density of a chemical substance increases or decreases
Facilitated Diffusion
involves passive movements of molecules along their concentration gradient, guided by the presence of another molecule- usually an integral membrane protein forming a pore or channel
the process in which the cell does not have to expend the energy to make it happen
osmosis
the movement of water across the cell membrane and the balance of water between the cell and its enviornments
Isotonic
there will be no net movement of water across the plasma membrane
hypertonic
when the cell loses water and shrivels and possibly dies
hypotonic
water will enter the cell faster than it leaves and the cell will swell and lyse like an overfilled water balloon
osmoregulation
the control of solute concentration and water balance
tonicity
the ability surrounding a solution to cause the cell to gain or lose water
Active Transport
move solutes against their concentration gradients
all carrier proteins rather than channel proteins
enables a cell to maintain internal concentration of small solutes that differ from concentrations in its enviornment
sodium potassium pump
exchanges sodium for potassium across the plasma membrane of animal cells
Electrochemical Gradient
the combination of forces acting on an ion
Proton Pump
actively transports protons out of the cell
drive the active transport of amino acids, sugars, and several other nutrients into the cell
Electrogenic Pump
a transport protein that generates voltage across a membrane
contransport
a transport protein that can couple the downhill diffusion of the solute of the uphill transport of a second substance against its own concentration gradient
Bulk Transport across the Plasma
Exocytosis
secretes certain molecules by the fusion of vesicles with the plasma membrane
secretory cells use exocytosis to export products
Endocytosis
the cell takes in molecules and particulate matter by forming new vesicles from the plasma membrane
phagocytosis
cellular eating
pinocytosis
cellular drinking
receptor mediated endocytosis
the take in of cholesterol for membrane synthesis and the synthesis of other steroids
Cell Fractionation
is a useful technique for studying cell structures and functions
Takes cells apart and separates major organelles and other subcelluar structures from one another
centrifuge
piece of equiptment that spins test tubes holding mixtures of disrupted cells at a series of increasing speeds
enables researchers to prepare specific cell components in bulks and identify their functions
Prokaryotic VS Eukaryotic Cells
Prokaryotic Cells
Lack nuclei and other membrane enclosed organelles
The DNA is concentrated in a region that is not membrane enclosed called the nucleoid
Eukaryotic Cells
have internal membranes that compartmentalize cellular functions
DNA is in an organelle called the nucleus, which is bounded by a double membrane