-highly organized, water-based compartment -filled with concentrated chemicals -bounded by a thin flexible "membrane"
The Cell Theory
-all organisms are composed of cells -the cell is the smallest "living" unit -all cells arise from pre-existing cells
Two membranes -inner one is folded into cristae -surrounds matrix main function is ATP production -"powerhouse" of the cell -site of cellular respiration -breakdown of organic molecules to produce energy -requires oxygen
Structures of plant cells
chloroplasts central vacuoles cell walls
Which organelle is the site of most of the cells protein synthesis?
In which organelle are steroid hormones synthesized?
the smooth ER
How many membranes surround a chloroplast from a plant cell?
Which type of cytoskeletal protein is responsible for the movement of chromosomes during cell division?
DNA strands can be visualized using which instrument?
The organelles and biomolecules present in homogenized cells can be separated by centrifugation. Which of the following would be found at the top of a centrifugation gradient?
Which organelle is found only in plants?
The endomembrane system contains what?
the golgi apparatus and ER
The presence of _______ means that substances must pass through, rather than between, the epithelial cells that form the lining of the small intestine.
Nucleic acids are not found in...
The proteins that make up the cytoskeleton of bacteria are similar to ______ in eukaryotic cells.
Which protein powers the movement of both cilia and vesicles within a cell?
Which organelle is involved in energy conversions?
Some proteins that are on the surface of mammalian cells contain carbohydrates. These proteins are synthesized by ______ and the sugars added in the _______.
the rough ER and golgi apparatus
present in nearly all plant cells
directly involved with the movement of organelles within a cell
A universal feature of receptors is that they
undergo structural (shape) changes when the signal molecule is bound.
In facilitated diffusion,
specific integral membrane proteins mediate transport.
cAMP is referred to as a
Which of the following molecules do you think would diffuse across a phospholipid bilayer fastest, assuming that there are no proteins associated with the bilayer? [Hint: Keep in mind the nature of the interior of the bilayer.]
Hormones are chemical signals that
travel through circulatory systems.
The phosphorylation of proteins by ATP
is catalyzed by enzymes known as "protein kinases."
binds to receptors in the brain
The sodium-potassium pump (or Na+-K+ pump)
results in the formation of Na+ concentration gradient across the plasma membrane.
What would happen if a suspension of red blood cells in an isotonic NaCl solution was suddenly diluted with pure water by a factor of 10?
The cells would swell and lyse (burst).
the movement of water across membranes.
Phospholipids spontaneously form bilayer structures, but oils form small droplets. Why do oils not form bilayers?
Oils do not have the polar head group that phospholipids have.
In addition to the bilayer lipids and proteins, membranes may contain _______ in the form of _______ and _______.
carbohydrates; glycoproteins; glycolipids
makes cAMP from ATP with the liberation of pyrophosphate (PPi).
Which step of the signal transduction cascade that results in glucose release during the "fight-or-flight" response does not directly involve a nucleotide?
Epinephrine binding to its receptor
Suppose the concentration of epinephrine in the blood stream of an animal drops. The cyclic AMP concentration in liver cells would be expected to _______ because _______ activity would _______.
decrease; adenylyl cyclase; decrease
In animals, cell recognition
involves proteins in plasma membranes.
results in the formation of clathrin-coated vesicles.
Chemical signal transduction pathways
involve binding of the signal molecule to receptors.
The mitochondrial ATP synthase
makes ATP at the expense of the proton gradient established by electron transport.
Reagents, such as dinitrophenol, increase the permeability of the mitochondrial inner membrane to protons. The addition of dinitrophenol to a suspension of animal cells should over the short term
inhibit mitochondrial ATP synthesis.
The ultimate source of energy for ATP synthesis in chloroplasts is
The major product of photosynthesis that is exported from the leaves to the rest of the plant is
In photosynthesis, NADPH is used for the
reduction of 3-phosphoglycerate (3PG).
is an oxidation-reduction process.
The immediate source of energy for ATP synthesis in chloroplasts is
the electrochemical proton gradient.
results in the formation of lactic acid or ethanol.
The end products of glycolysis are
pyruvate, ATP, and NADH.
a complex of pigments, proteins, and a reaction center chlorophyll
releases less energy than glycolysis
citric acid cycle
In green plant photosynthesis, water is
oxidized to oxygen gas (O2) in the light
The mitochondrial electron transport chain
oxidizes the intermediate electron carriers, NADH and FADH2.
Endergonic reactions are A) nonspontaneous B) spontaneous
A graph of light absorption versus wavelength of light; shows how much light is absorbed at each wavelength.
A graph of a biological process versus light wavelength; shows which wavelengths are involved in the process.
presence of oxygen; requiring oxygen. (Contrast with anaerobic.)
Occurring without the use of molecular oxygen, O2. (Contrast with aerobic.)
The phase of photosynthesis in which chemical energy captured in the light reactions is used to drive the reduction of CO2 to form carbohydrates
The catabolic pathways by which electrons are removed from various molecules and passed through intermediate electron carriers to O2, generating H2O and releasing energy.
In photosynthetic light reactions, the flow of electrons that produces ATP but no NADPH or O2
cyclic electron transport
The anaerobic degradation of a substance such as glucose to smaller molecules such as lactic acid or alcohol with the extraction of energy.
The biochemical synthesis of glucose from other substances, such as amino acids, lactate, and glycerol
An organism that requires preformed organic molecules as food
ATP formation in the mitochondrion, associated with flow of electrons through the respiratory chain.
A quantum of visible radiation; a "packet" of light energy.
Regulation of the activity of a protein (usually an enzyme) by the binding of an effector molecule to a site other than the active site.
A transport protein in plant and animal cell membranes through which water passes in osmosis.
A chemical signal that binds to and affects the cell that makes it
A compound formed from ATP that acts as a second messenger.
cAMP (cyclic AMP)
A process by which liquids or solid particles are taken up by a cell through invagination of the plasma membrane
A process by which a vesicle within a cell fuses with the plasma membrane and releases its contents to the outside
Passive movement through a membrane involving a specific carrier protein; does not proceed against a concentration gradient.
A lipid to which sugars are attached.
A protein in which sugars are attached
Any molecule that binds to a receptor site of another (usually larger) molecule
Pertaining to a chemical signal, such as a hormone, that acts locally, near the site of its secretion
Diffusion across a membrane; may or may not require a channel or carrier protein
Endocytosis by a cell of another cell or large particle.
Endocytosis by a cell of liquid containing dissolved substances.
The hydrostatic pressure of an enclosed solution in excess of the surrounding atmospheric pressure
An enzyme that catalyzes the addition of a phosphate group from ATP to a target protein.
Allowing certain substances to pass through while other substances are excluded; a characteristic of membranes
Cell that is responsive to a particular type of physical or chemical stimulation.
sensory receptor cell
The series of biochemical steps whereby a stimulus to a cell (such as a hormone or neurotransmitter binding to a receptor) is translated into a response of the cell.
signal transduction pathway
An integral membrane protein that spans the phospholipid bilayer.