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Capacity to perform work; work moves thing in ways they wouldn't move if left alone
Energy of motion (Diver climbing up the steps to diving platform)
Energy-releasing chemical breakdown of fuel molecules & storage of energy in form that cell can use to perform work
What is "Combustion" of fuels in cells which is more gradual & efficient "burning" off fuels?
Conservation of Energy Principle
- Not possible to destroy/create energy
- Energy can only be converted from one form to another
Chem energy release by breakdown o organic molecules during cellular respiration is used to generate what?
Molecules of ATP (those power cellular work)
Conservation of Matter Principle
Matter can't be created/destroyed but can only be converted from one form to another
- Energy that an object has because of its location/structure
- **Ex: Energy contained by water behind a dam
- Type of kinetic energy contained in random motion of atoms & molecules
- ** All energy conversions generate some heat; makes energy less useful; Heat difficult to "tame"
- Measure of amount of disorder, or randomness, in system
- Everytime energy is converted from one form to another, entropy increases
In both cases of living cells & auto engines, this process of ENERGY CONVERSION breaks organic fuel into smaller waste molecules that have much less chem energy than fuel molecules did, thereby releasing energy that can be used to perform work
- Energy stored in chem bonds of molecules
- **Living cells & automobile engines use same basic process to make chem energy stored in their fuels available for work
Which special form of potential energy is in molecules of food, gas, & other fuels?
About 25% of the energy that a car engine extracts from its fuel is converted to the kinetic energy of car's movement. The rest of the 75% is converted to what?
About 40% of our food energy is for what, as to where 60% released by breakdown of fuel molecules generates body heat?
Useful work (contraction of muscles)
- Units of energy; amount of energy that can raise temp of 1 gram (g) of water by 1 degree C
- **Kilocalories (kcal) Units of 1,000 cal <--For conventional use
Kilocalories (Capital C)
Calories on a food package
Some Caloric Accounting
Structure of ATP (adenosine triphosphate)
- Consists of organic molecule called Adenosine, plus a tail of 3 phosphate groups
- Triphosphate tail provides energy needed for cellular work
- Each phosphate group is neg charged (Charge repels eachother; contributes to potential energy of ATP)
Transfer of phosphate from triphosphate tail to other molecules provides energy for cellular work
ADP (adenosine diphosphate)
- 2 phosphate group tails instead of 3
- **3rd phosphate group transferred to another molecule
When ATP drives work in cells, ATP energizes other molecules in cells by transferring phosphate groups to these molecules
Phosphate Transfer helps cells perform 3 main kinds of work:
- Motor protein performing **Mechanical work
- Transport protein performing **Transport work
- Chemical reactants performing **Chem work
- ----All these types of work occur when target molecules accept a phosphate group from ATP
Phosphate Transfer: Motor Proteins
- In our muscles, ATP transfers phosphate groups to motor proteins that change shape, causing muscle cells to contract & perform mechanical work.
- **Ex: Bicyclist pedaling up a hill
Phosphate Transfer: Transport proteins
Transport of ions & other solutes across membranes of brain cells preparing cells to transmit signals to muscles & other tissues.
Phosphate Transfer: Chemical reactants
ATP drives chem work of makin some of cell's large molecules. All types of work occur when target molecules accept phosphate group from ATP
- Cells spend it continously; renewable source
- Can be restored by adding phosphate group back to ADP (takes energy; like recompressing a spring and food reenters the story)
- 3rd phosphate group acts s energy shuttle within ATP cycle
- ----Working muscle cell recycles all of its ATP about once every minute (10 million ATP molecules spent & regenerated per second per cell)
In a sense, a living organism is a complex what?
Complex "chemical square dance", w/ molecular "dancers" continually changing partners via chem reactions which are chem bonds supposed to be broken, "swapping partners letting go of partner's hand"
- Total of all chem reactions in organism
- Almost NO metabolic reactions occur w/out help & most require assistance of enzymes
- Proteins that speed up chem reactions
- Serve as biological catalyst changing rate of chem reaction w/out itself being changed in process
How many living cells contain thousands of diff enzymes each promoting diff chem reaction?
All living cells
Amount of energy that reactants must absorb before chem reaction will start; activates reactants & triggers chem reaction
Enzymes & Activation Energy
- W/out enzyme, rectant molecule must overcome Activation Energy BARRIER before chem reaction can break molecule into products
- W/ enzyme, it speeds process by lowering Activation Energy BARRIER
- Interaction where substrate slips into the enzyme's docking station, active site changes shape slightly to embrace substrate & catalyze reaction; FIT is more snug
- **Ex: Shaking someone's hand
- Very selective in reaction it catalyzes; specificity is based on ability to recognize certain reactant molecule
- **(Depends on enzyme's shape)
Region of enzyme that has shape & chemistry that fit substrate molecule
How an Enzyme works
- 1.Active site EMPTY, Substrate (sucrose) can accept molecule of its substrate
- 2. Substrate binds to enzyme at Active site
- 3. Enzyme catalyzes chem reaction, converting substrate into product
- 4. Products are released, & sucrase can accept another molecule of substrate
- ----Key characteristic is ability to function repeatedly
Like sucrase, many enzymes are named for their substrates, but......
w/ an "-ase" ending.
- Chemicals that interfere w/ enzyme's activity by changing its shape, by plugging up active site or binding to another
- ---Some are actually substrate imposters that plug up active site (Can't shake person's hand if someone else puts a banana in it first!)
- It can change Enzyme's SHAPE, not accepting substrate anymore (Tickled at rib cage clenching hand to close)
- Method of metabolic control in which end product of metabolic pathway acts as inhibitor of enzyme w/in pathway
- ---Keeps cell from wasting resources that could be put to better use
In addition to drugs, many toxins & poisons....
are irreversible inhibitors
Many Antibiotics work by inhibiting enzymes of disease-causing...
Primary functions of plasma membrane proteins
- Regulates passage of materials into & out of cell
- ----2 adjacent membranes, all 6 types of membrane proteins are shown for convenience. An actual cell may have just a few of these types of proteins
Primary Functions of Membrane Proteins: Cell-cell recognition
Some proteins w/ chains of sugars serve as ID tags recognized by other cells
Primary Functions of Membrane Proteins: Intracellular joining
Proteins may link adjacent cells
Primary Functions of Membrane Proteins: Transport Proteins
- CRITICAL & help move substances across cell membrane
- ***Protein may provide a channel for a solute
Primary Functions of Membrane Proteins: Attachment to cytoskeleton & extracellular matrix
Such proteins help maintain cell shape & coordinate changes
Primary Functions of Membrane Proteins: Enzymatic activity
This protein & the one next to it are enzymes, having active site that fits a substrate. Enzymes may form a team that carries our steps of a pathway
Primary Functions of Membrane Proteins: Cell Signaling
Binding site fits shape of chem messenger. Messenger may cause change in protein that relays the message to inside of cell
Living thing & automobile engines use same basic process where it breaks organic fuel into smaller waste molecules using oxygen to make what?
Chemical energy (Stored in their fuels available for work)
How can an object at rest have energy?
It can have potential energy cuz of its location or structure
The act of diving off the platform into the water converts the potential energy back to what kind of energy?
Which form of energy is most randomized and difficult to put to work?
- Movement of molecules of any substance so they spread out into available space
- **Ex: Removing cap from perfume bottle, releasing fumes (molecules) all around randomly
- Diffusion of substance across biological membrane w/out any input of energy
- Cell membrane does play a regulatory role by being selectively permeable
- **Ex: Small molecules (CO2, O2) generally pass thru more readily than larger molecules like amino acids
How is facilitated diffusion a form of passive transport?
It uses proteins to transport materials down a concentration gradient w/out expending energy
- Can pass through the membrane
- ***Sometimes membrane is impermeable to some small substances like Hydrogen ions (H+) & other inorganic ions which are to hydrophilic to pass thru phospholipid bilayer
- Region in which substance's density changes; moves from where it's more concentrated to where it's less concentrated
- **Ex: Our lungs= Passive transport along THIS is sole means by which O2, essential for metabolism, enters blood & CO2, metabolic waste, passes out of it
- Passage of substance across biological membrane down its concentration gradient, aided by specific transport proteins
- DOESN'T require energy & driving force is concentration gradient
- ---W/out the protein, substance doesn't cross membrane or diffuses across it too slowly to be useful to cell
- Diffusion of water across selectively permeable membrane
- Ppl take advantage of it to preserve foods
- When solution has higher solute concentration
- **Hypertonic to the other solution
- ---Has lower water concentration
- When solution has lower solute concentration
- **Hypotonic to the other solution
- ---Has higher water concentration
When it come to Osmosis, the water will diffuse across the membrane along its concentration gradient from area of high water concentration (hypotonic) to....
- ...one of lower water concentration (hypertonic).
- This reduces the diff in solute concentrations & changes volumes of 2 solutions
Solutions of equal solute concentration
The behavior of ANIMAL & PLANT cells in diff Osmotic environments:
- --Animal Cell:
- 1.)Isotonic= Normal
- 2.)Hypotonic= Lysing(Burst)
- 3.)Hypertonic= Shriveled
- --Plant Cell:
- 1.)Isotonic= Flaccid(Floppy)
- 2.)Hypotonic=Turgid(Firm); Healthiest
- 3.)Hypertonic= Shriveled
- The control of water balance
- **Ex: Freshwater Fish, gills & kidneys constantly prevent excessive water buildup
Process example: As a plant cell loses water, it shrivels, & its plasma membrane pulls away from the cell wall
- Requires that cell expand energy to move molecules across a membrane
- Transport proteins are specific in their recognition of atoms or molecules & have binding site that accepts only certain solute
- Uses energy from ATP, the protein pumps solute against its concentration gradient (Away from side w/ less concentration, towards side w/ more concentration)
- Enables cells to maintain internal concentrations of small solutes that differ from environmental concentrations
Particular Active Transport Case "Sodium-potassium pump"
- Animal nerve cell has much higher concentration of potassium ions & lower concentration of sodium ions
- Plasma membrane helps maintain diff.s by pumping sodium out of cell & potassium into cell.
- **Vital in the propagation of nerve signals
- During protein production by cell, secretory proteins exit cell from transport vesicles that fuse w/ plasma membrane, spilling contents outside cell
- **Ex: When u cry, cells in ur tear glands use this process to export salty tears
Takes material into cell w/in vesicles that bud inward from plasma membrane
3 types of Endocytosis:
- Receptor-mediated Endocytosis
- Cell engulfs particle & packages it w/in food vacuole
- "Cellular eating"
- Cell "gulps" droplets of fluid by forming vesicles. Both Phagocytosis & Pinocytosis are nonspecific in substances transported
- "Cellular drinking"
Endocytosis: Receptor-mediated Endocytosis
- Triggered by binding of certain external molecules to specific receptor proteins built into plasma membrane.
- This binding causes local regain of membrane to form vesicle that transports specfic substance into cell
- Very specific
Signal Transduction pathway
Series of molecular changes that converts signal on target cell's surface to specific response inside cell
Cell Signaling: Signal Reception, Transduction, & Response
- Person gets "psyched up", certain cels in adrenal glands secrete epinephrine hormone (adrenaline) into bloodstream.
- Hormone reaches muscle cells & recognizes by receptor proteins in plasma membrane
- Recognition triggers responses in muscle cells w/out hormone even entering
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