• measurement of the disorder of a system
• life requires energy to fight disorder

• energy is released
• reactants contain more energy than products
• "down-hill"
• ex: cellular respiration

• energy is absorbed
• products contain more energy than reactants
• "up-hill"
• ex: formation of glucose

• energy needed to force the elctron shells of reactants together prior to the formation of products
• initial "push" to start a reaction
• source: kinetic energy of movement

• an exergonic reaction provides the energy needed to drive an endergonic reaction
• an endergonic reaction cannot occur unless somewhere else in the body an exergonic reaction has occurred to provide the energy to drive them

• energy currency of cells
• energy stored within its chemical bonds
• ATP -> ADP + P = heat given off
• usually only the last phosphate bond is broken

• substances that speed up chemical reactions
• catalysts do not cause a reaction that would not occur without it
• can be reused
• speed up reaction by lowering the activation energy

• a type of protein that binds to a substrate molecule to speed up a chemical reaction
• biological catalyst
• specific for certain molecules

• pocket in an enzyme that allows for the bonding of the molecules each enzyme specifically reacts with
• has a distinctive shape
• only certain molecules can enter

1. substrates enter active site in specific orientation
2. substrates and active site change shape promoting a reaction between substrates
3. substrates are now bonded together and leave enzyme
4. enzyme is ready for new substrates

• anabolic
• usually via dehydration synthesis

• catabolic
• usually via hydrolysis

• aka negative feedback
• the activity of an enzyme is inhibited by its own product or by a subsequent product produced farther along in a metabolic pathway
• prevents the cell from wasting chemical resources to synthesize more of something than it needs
• when concentrations drop and fewer molecules are available to inhibit the enzyme, the pathway resumes production

• enzyme action is enhanced or inhibited by molecules that act as regulators
• do not bind to active site, but to the allosteric site
• when its bound the active site of enzyme will change, either increasing or decreasing enzyme activity

(aka noncompetitive inhibitor)

allosteric inhibitor binds to allosteric site & alters the shape of the enzyme so the active site is no longer functional

• competitive inhibitor binds to active site so that substrate can no longer bond
• can be overcome by increase in substrate concentration

• extreme pH
• salt concentration
• extreme temperature

• protein unravels & becomes biologically inactive
• occurs under extreme pH, salt concentration, & extreme temperature

• eukaryotic plants
• some protists
• some prokaryotes
• AUTOTROPHS

• cuticle
• upper & lower epidermis
• mesophyll
  • palisades
  • spongy
• bundle sheath cells
• vascular bundle
• guard cells
• stoma

• waxy covering of epidermis
• lipids
• water-proof coating that prevents water loss

(aka veins)

supply water to the mesophyll cells and carries the glucose they make to other parts of the plant

• stroma
• thylakoids
• grana
• inner membrane
• outer membrane

• aka light reaction
• chlorophyll embedded within the membranes of thylakoids capture light energy
• energy is converted into chemical energy, stored in energy carrier molecules (ATP & NADPH)

• aka dark reaction, Calvin-Benson cycle, C3 cycle
• enzymes in the stroma use the chemical energy of energy carrier molecules to drive the synthesis of glucose

• individual packets of energy
• energy corresponds to wavelength
  • short = high energy - dangerous
  • long = low energy - safe

• behaves as both a particle & a wave
• travels as photons
• form of radiant energy (travels through space in waves)

λ

distance between crests of 2 successive waves

• consists of wavelengths with energies strong enough to alter the shape of pigments but weak enough not to damage molecules like DNA
• wavelenghs stimulate pigments in eyes
• correspond to colors of rainbow

Oxidation Is Losing

Reduction Is Gaining

(losing/gaining electrons and/or H⁺)

• light-harvesting complex and its associated electron transport chain located in thylakoid membranes
• contain chloropyll & accessory pigments

enzymes use light energy to break up water

H₂O + light -> 2e^- + H + 2O₂

• produces only ATP
• occurs when e^- energized in PS1 are "recycled"
• e's from PS1 join protein carries and generate ATP as they pass along the ETC
• do not become incorporated with NADPH
• e's return to PS1 and can be energized again
• considered primitive form of photosynthesis

• osmosis of a chemical (in this case H⁺)
• an energy coupling mechanism that uses energy stored in the form of a hydrogen ion gradient across a membrane to drive cellular work
• occurs along the membrane of thylakoid which has embedded protein pumps

• embedded within thylakoid membrane
• only place where proteins can exit the membrane
• activated by H's bonding to top
  • stimulates bonding of ADP and Pi to make ATP

• the enzyme that will join RuBP to CO₂
• process known as carbon fixation

• when water supply is adequate, stomata open letter CO₂ in and O₂ and water out
• when water supply is inadequate, stomata close, reducing transpiration
  • reduces CO₂ intake
  • limits ability to release O₂

• when O₂ is bound to rubisco instead of CO₂
• wasteful
• no carbon added to Calvin cycle
• uses up ATP instead of making it

• photorespiration problematic - have developed adaptations
• ex: sugarcane, corn, crab grass
• found in hot, dry, climates
• high rate of photosynthesis -> can reduce time that stomata are open -> reduces water loss

1. mesophyll cells
2. bundle sheath cells

1. CO₂ absorbed by mesophyll cells
2. CO₂ combines with PEP (3-C) to form OAA (4-C) (enzyme: PEP carboxylase)
3. OAA converted to Malate (4-C)
4. Malate shuttled to bundle sheath cells
5. Malate converted to pyruvate (3-C) and CO₂
6. pyruvate goes back to mesophyll cells and is converted intp PEP
7. CO₂ is still in bundle sheath cells - does not have to compete with O₂ for rubisco

1. PEP carboxylase fixes CO₂ into OAA
2. OAA is converted into malic acid
3. malic acid shuttled to vacuole of cell
4. stomata open only at night - PEP carboxylase only active at night; malic acid accumulates in vacuole at night
5. stomata closed during the day - malic acid shuttled out of vacuole & converted to OAA -> releases CO₂, CO₂ fixed by rubisco & Calvin cycle proceeds

• grow in hot, dry, environments with cool nights
• ex: cacti & pineapples