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Explain how ATP powers cellular work
ATP consists of an organic molecule called adenosine plus a tail of three phosphate groups that are the "business" end of ATP that actually provides energy for cellular work
Each phosphate group is negatively charged; negative charges repel each other—this the crowding of triphosphate tails contribute to ATP's potential energy (analogous to storing energy by compressing a spring)
Releasing a triphosphate tail makes energy available for working cells—resulting in ADP
The transfer of phosphate groups help the cell do mechanical work, transport work, and chemical work—in all three types, the target molecule always accepts the phosphate group from the ATP
ATP transfers a phosphate group to another molecule, increasing that molecule's energy content
Explain how ATP is recycled
ATP is restored by adding a phosphate group back to ADP—adenosine diphosphate
Chemical energy that cellular respiration harvests from sugars and other organic fuels is put to work regenerating a cell's supply of ATP
Cellular work spends ATP, which is recycled when ADP and phosphate is combined using energy teased by cellular respiration
ATP cycle runs at an astonishing pace: up to 10 million ATPs are consumed and recycled each second I'm a working muscle cell
Explain why enzymes are needed in living organisms
Most metabolic reactions require the assistance of enzymes
ENZYMES: proteins that speed up chemical reactions
Explain how enzymes are able to speed up specific chemical reactions
Enzymes lower the amount of activation energy needed to break the bonds of reactant molecules, allowing a chemical reaction to take place at a faster rate
Activation energy is like a barrier to a chemical reaction and the enzyme's function is to lower that barrier; it does so by binding to reactant molecules and putting them under physical/chemical stress, making it easier to break their bonds and start a reaction
Explain how factors such as PH and temperature can affect enzyme activity
a. as temperature increases, so does the rate of reaction because the molecules are moving faster and have a higher chance of hitting eachother
b. at extremely high temperatures, the enzyme is denatured due to disruption of noncovalent bonds
c. lower temperatures the substrate molecules do not have enough kinetic energy for the reaction to take place even in the presence of the enzyme
a. changes shape of enzyme by interacting with noncovalent bonds
b. also changes shape or charge properties of the substrate so
that either the substrate cannot bind to the active site or it cannot undergo catalysis
c. As pH increases, enzyme activity increases until it reaches an optimal point in which enzymes denatures and as pH increases, enzyme activity decreases.
Define and distinguish between the following pairs of terms: diffusion versus osmosis, passive transport versus active transport, hypertonic versus hypotonic, endocytosis versus sexocytosis, and phagocytosis versus pinocytosis.
DIFFUSION: the natural movement of molecules spreading out evenly into the available space
OSMOSIS: the diffusion of water across a semipermeable membrane
PASSIVE TRANSPORT: diffusion across a membrane is an example of this—the cell does not expend any energy for it to happen—the substance diffuses down the concentration gradient
ACTIVE TRANSPORT: requires that the cell expends energy to move molecules across a membrane; cellular energy is used to drive a transport protein that pumps a solute against the solute's concentration gradient; allows cells to maintain internal concentrations of small solute's that differ from environmental concentrations
HYPERTONIC: the solution with a higher concentration of the solute to the other solution—sucked out
HYPOTONIC: the solution with the lower solute concentration to the other—blows up
ENDOCYTOSIS: substances exit the cell from transport vesicles that fuse with the plasma membrane, spilling the contents outside the cell
ENDOCYTOSIS: cell takes in material via vesicles that bud inward
PHAGOCYTOSIS: "cellular eating" a cell engulfs a particle and packages it within a food vacuole
PINOCYTOSIS: like phagocytosis, however the cell takes in fluids
Major function of membrane proteins
Attachment to the cytoskeleton and extracellular matrix
Describe the fluid mosaic model of the cell membrane
The membrane is not stuck rigidly in place, rather, the phospholipids and most of the proteins can freely drift about in the plane of the membrane; fluid mosaic: fluid—molecules can freely move past one another || mosaic—diversity of proteins that float like icebergs in the phospholipid sea
3 types of cellular work
Chemical work: the pushing of endergonic reactions.
Transport work: the pumping of substances across membranes against the direction of spontaneous movement.
Mechanical work: the contraction of muscle cells and the movement of chromosomes during cellular reproduction.
The capacity to do work
Entropy means that...
The quantity of usable energy declines with each energy transformation.
Molecules of food have a special form of potential energy called...
What materials are found in a molecule of ATP?
An organic molecule called adenosine plus three phosphate groups.
ATP drives work in cells by.... to other molecules.
An enzyme is a protein that...
Changes the rate of a metabolic reaction without being consumed by the reaction
Activation energy can be described as....
Energy needed to activate the reactants and trigger a chemical reaction
Many metabolic pathways are slowed by inhibiting an enzyme required for a particular product.
A primary function of the cell membrane is to..
Register the passage of materials into and out of the cell
An animal cell placed in a hypertonic solution will...
Lose water by osmosis and shrivel
In osmosis water moves toward the... solution that is toward the solution with the ... solute concentration.
The passive transport of water across a selectively permeable membrane is called...
Term used to describe an animals ability to survive if the cells are exposed to a hypotonic or hypertonic environment...
The use of energy to move molecules across a membrane defines...
Conservation of energy
machines and organisms can transform kinetic energy to potential and vice versa. In all such energy transformations, total energy is conserved. Energy cannot be created nor destroyed.
measure of disorder or randomness. every energy conversion releases some randomized energy in the form of heat.
molecules store varying amounts of potential energy in the arrangement of their atoms. organic compounds are relatively rich in it.
Enzymes are biological catalysts that speed up metabolic reactions by lowering the activation energy required to break the bonds of reactant molecules.
the entry of a substrate into the active site of an enzyme causes the enzyme to change shape slightly, allowing for a better fit and thereby promoting the interaction of enzyme with substrate.
proteins embedded in the plasma membrane perform a wide variety of functions, including regulating transport.
passive transport, osmosis and active transport
exocytosis and endocytosis
exocytosis is the secretion of large molecules within vesicles. The three kinds of endocytosis are phagocytosis ("cellular eating"), pinocytosis ("cellular drinking") and receptor mediated endocytosis, which enables the cell to take in specific large molecules.
the role of membranes in cell signaling
receptors on the cell surface trigger signal transduction pathways that control processes within the cell
the control of water balance within a cell or organism
most animal cells require a ... environment. plant cells need a .... environment which keeps walled cells turgid.
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