How can an object at rest have energy?
It can have potential energy b/c irs location or structure.
What is kinetic energy?
The energy of motion.
What does the conservation of energy mean?
Energy cannot be created or destroyed, only converted.
What is entropy?
Measures the amount of disorder or randomness in a system.
What is chemical energy?
Arises from the arrangement of atoms.
Which energy is most randomized and difficult to put to work?
What does calorie mean?
The amount of energy that can raise the temp of 1g of water by 1 degree celcius.
What is ATP (Adenosine Triphosphate)?
-Consists of an organic molecule called adenosince plus a tail of phosphate groups.
-Energizes other molecules in cells by transferring phosphate groups to those molecules.
-Enables the transport of ions and other solutes across the membranes of the rider's brain cells.
What is metabolism?
The total of all chemical reactions in an organism.
What are enzymes?
Proteins that speed up chemical reactions.
What needs to happen before a chemical reaction to begin?
Chemical bonds in the reactant molecules must be broken.
What is activation energy?
Activates the reactants and triggers the chemical reaction.
How do enzymes enable metabolism to occur?
By reducing the amount of activation energy required to break the bonds of reactant molecules.
How does ATP powers cellular work?
ATP transfers a phosphate group to another molecule, increasing that molecule's energy.
What is a substrate?
The enzyme's ability to recognize a certain reactant molecule.
What is the active site?
A region of the enzyme that has a shape and chemistry that fit the substrate molecule.
What is induced fit?
When a substrate slips into this docking station, the active site changes shape slightly to embrace the substrate and catalyze the reaction.
Describe how an enzyme works.
-W/ it's active site empty, sucrase can accept a molecule of its substrate.
-Substrate binds to the enzyme and the active site.
-The enzyme catalyzes the chemical reaction, converting substrate into product.
-The products are released, and sucrase can accepts another molecule of substrate.
What are enzyme inhibitors?
Substrate impostors that plug up the active site.
What is feedback regulation?
Keeps the cell from wasting resources that could be put to better use.
What are transport proteins?
Membrane proteins that help substances across a cell membrane.
What are the 6 main functions of membrane proteins.
- Cell Signaling
- Attachment to the cytoskeleton and extracellular matrix
- Intercellular joining
- Cell - cell recognition
- Enzymatic activity
What is diffusion?
The movement of molecules of any substance so that they spread out into the available space.
What is passive transport?
Diffusion across a membrane - does not require any energy.
How is facilitated diffusion a form of passive transport?
It uses proteins to transport materials down a concentration gradient w/o expending energy.
What is a concentration gradient?
A region in which the substance's density changes.
What is osmosis?
The diffusion of water across a selectively permeable membrane.
What is a hypertonic?
The solution w/ a higher concentration of solute when compared to another.
What is a hypotonic?
The solution w/ a lower concentration of solute when compared to another. (has the highest water concentration)
What is an isotonic?
Solutions of equal solute concentration.
What does the survival of a cell depend on ?
It's ability to balance water uptake and loss.
What is osmoregulation?
The control of water balance.
What is a plasmolysis?
The process where a plant cell loses water, it shrivels, and its plasma membranes pull away from the cell wall.
What is active transport?
Requires that a cell expend energy to move molecules off a membrane.
What molecule is the usual energy source for active transport?
What is endocytosis?
Takes material into the cell within vesicles that bud inward from the plasma membrane.
What are 3 types of Endocytosis?
What is Phagocytosis?
"cellular eating" a cell engulfs a particle and packages it w/i a food vacuole.
What is Pinocytosis?
"cellular drinking" the cell gulps droplets of fluid by forming vesicles.
What is receptor-mediated edocytosis?
Triggered by the binding of certain external molecules to specific receptor proteins built into the human cell.
How can a molcule change a cell w/o entering it?
It can bind to a membrane protein that triggers a signal transduction pathway.
What is a key step in the origin of life?
The spontaneous formation of membranes.
Nanotechnology may eventually produce tiny robots with glycolytic enzymes that use______ as an energy source.
Most cellular work is accomplished by _____ energizing molecules by __________ them.
ATP ... transferring a phosphate group to
A relaxed spring is to a compressed spring, as _____ is to _____.
ADP ... ATP
The mechanism of enzyme action is __________.
to lower the energy of activation of a reaction
Why does the process of gene evolution sometimes first involve duplication of a gene?
Duplication means that mutations can occur in one gene while the other continues to produce a functional protein.
Why doesn't the antibiotic penicillin harm humans?
Human cells do not have cell walls.
he movement of atoms, ions, or molecules from a region of higher concentration to regions of lower concentration is called _____.
Cells A and B are the same size and shape, but cell A is metabolically quiet and cell B is actively consuming oxygen. Oxygen will diffuse more quickly into cell _____ because __________.
B ... the diffusion gradient there is steeper
The diffusion of water across a selectively permeable membrane is called _____.
Seawater is dangerous to drink because __________.
seawater is hypertonic to your body tissues and drinking it will cause you to lose water by osmosis
A plant cell placed in a hypotonic solution will not lyse because __________.
the cell wall prevents the plant cell from bursting
If the volume of a cell increases when it is placed in a solution, that solution is said to be _____ to the cell.
When in solution, a molecule that moves slowly across an artificial membrane moves rapidly across a plasma membrane. This occurs regardless of whether the concentration of this molecule is higher inside or outside the cell. Using this information, which transport mechanism is most likely to be responsible for the movement of the molecule across a plasma membrane?
The transport of molecules of a particular solute from inside an animal cell across the cell membrane to the extracellular fluid always requires energy when __________
the concentration of the solute is lower inside the cell than outside it
A nursing infant is able to obtain disease-fighting antibodies, which are large protein molecules, from its mother's milk. These molecules probably enter the cells lining the baby's digestive tract via _____.
Some liver cells ingest bacteria, a function probably accomplished by _____.
The secretion of neurotransmitters out of the nerve cell, from small vesicles at the end of the axon, can be considered an example of _____.
Cellular responses involve _____ of an external signal.