• system's energy available for work
• can perform work when the temperature and pressure are uniform throughout the whole system

• when the DeltaG is negative; loss of free energy, final state is more stable because is lless likely to change now
• does not requre the input of energy
• for this process to occur, must increase the entropy of the earth
• ex.: flowing of water downward

• energy is EXITing --> catabolic rxns.
• provides energy for cell. respiration and light energy
• occurs spontaneously

• state of maximum stability
• amount of free energy goes down when reaching equilibrium
• no work can be performed when in this state, a cell is dead if it is at metabolic equilibrium

• Adenonsine Triphosphate; bonds b/w phosphate groups can be broken by hydrolysis 
• ATP + H2O --> ADP + Pi DeltaG = -7.3 kcal/mo

-->exergonic rxn.

• contains sugar ribose, nitrogenous base adenine, and 3 phosphate groups

reverse reaction--endergonic

ADP + Pi --> ATP + H2O

DeltaG = +7.3 kcal/mol --> takes energy to make

• pushing of endergonic reactions that would not occur spontaneously
• construction of polymers from monomers

• speed up rxns by lowering the activation energy

resemble substrate and compete for an active site 

ex. : toxins and poisons 

a regulatory molecule binds at one site which affects the activity at a separate site

--> either stimulates or inhibits activity

the end product of a pathway binds to an enzyme that acts earlier in the pathway and inhibits it

--> prevents cell from wasting energy to make excess product

• electrons stripped from glucose at key steps and travel with a protein
• C6H1206 + 6O2 --> 6CO2 + 6H20

• Step 1: takes place in cytosol
• splits glucose into 2 molecules of pyruvate
• requires input of 2 ATP, outputs 4 --> net yield of 2 ATP

• recipient with phosphate group covalently bonded to it
• is more reactive--less stable

• pyruvate enters mitochondria thru active transport
• --> COO- is removed and given off as CO2
• -->the remaining 2-carbon molecule is oxidized--NADH is formed
• -->coenzyme A is added to corm acetyl coA

• occurs in mitochondrial matrix
• 1 cycle produces: 2CO2, 1 GTP (ATP), 3 NADH, 1 FADH2
• coA and oxaloacetate are recycled
• 2 ATP produced

Oxidative Phosphorylation

2 steps:

• 1. electron transport chain
• 2. chemiosmosis 
• generates ATP by adding Pi to ADP
• where majority of ATP is produced

• collection of molecules embedded in the mitochondrial inner membrane
• electrons are dropped off by NADH and FADH2
• carriers alternate between reduced and oxidized states as they accept and donate electrons
• final acceptor is oxygen which picks up 2 H+ ions to form H2) -->no ATP production

• used to pump H+ ions across the membrane by an exergonic flow --> generates a gradient = proton motive force
• it is an energy-coupling mechanism that drives cellular work by using energy stored in a H+ gradient 

• how animals reduce the efficiency of respiration
• brown fat cells full of mitochondria which in the innermembrane an uncoupling protein allows H+ ions to flow down their gradient without producing ATP --> generates heat without the buildup of ATP

• uses electron transport chain, but O2 is not the final acceptor --> other electronegatice substances can also work (such as SO4^2-)
• **aerobic respiration produces 16x more ATP per glucose molecule than fermentation**

• generates energy without oxygen or electron transport chain --> extension of glycolysis 
• consists of glycolysis plus regeneration of NAD+ (transfering of electrons from NADH to pyruvate, or derivatives of pyruvate) --> reused to oxidize sugar, thus generating 2 ATP by substrate-level phosphorylation

• pyruvate is reduced to ethanol
• 2 steps: 1. CO2 released from pyruvate, then converted to 2-carbon acetaldehyde                                2. acetaldehyde reduced by NADH to ethanol --> regenerates supply of NAD+ for glycolysis
• used in winemaking, beer, and baking --> CO2 bubbles created by yiest allows bread to rise

• pyruvate is reduced directly by NADH to form lactate --> can use this process when supply of oxygen can't keep up with the energy demand (muscle cells), no release of CO2
• used in dairy industry for cheeses and yogurt

• 12 H2O + 6 CO2 + Light Energy --> C6H12O6 + 6 H2O + 6 CO2 --> converting light to chemical energy
• is a redox reaction, water is split into hydrogen and oxygen atoms, the electrons and H+ ions are transferred to CO2, reducing it to sugar
• electrons increase in potential energy--> endergonic reaction

• form of energy = electromagnetic radiation

• substance that absorbs visible light
• chlorophyll a & b do appear green because they do not absorb wavelengths in that part of the spectrum, thus reflecting green

• Light + H2O --> ATP + NADPH + O2
• Convet light into chemical energy
• H2O is split to provide electrons and H+ ions --> to acceptor NADP+, temporarily stored
• NADP+ is reduced to NADPH using solar power by adding electrons and H+
• ATP is produced through photophosphorylation
• O2 is given off

• located in thylakoid membrane--is a photosystem which captures light
• contains pigment molecules attached to proteins which capture light and transfer the energy to the reaction-center complex

• contains a special pair of chlorophyll a --> can reduce the primary electron acceptor

• uses the ATP and NADPH to reduce CO2 to sugar (G3P), occurs in the stroma
• 3 phases: carbon fixation, reduction, regeneration
• cycle occurs 3x to produce 1 net G3P, uses 9 ATP and 6 NADH
• does not require light directly, but usually done during the day***

• initial corporation of carbon into organic molecules
• RuBP carboxylases attaches CO2 to RuBP

• a carbon intermediate receives a phosphate group from ATP, the phosphate is reduced by NADPH and loses the phosphate = G3P
• reduces the fixed carbon to carbohydrate by adding electrons --> powered by NADPH

• series of steps in which ATP is used to rearrange 5 molecules of G3P to regenerate RuBP
• now prepared to receive CO2 again, cycle continues

• carbon fixation is SPATIALLY separate from Calvin Cycle
• CO2 is fixed by PEP carboxylase in mesophyll cells to form 4-carbon product --> transferred to bundle sheath cells and releases CO2 and added to Calvin Cycle by rubisco

• carbon cycle fixed serparetly by Calvin Cycle TEMPORARILY
• close their stoma during the day to conserve H2O
• open at night, take in CO2 and fix into organic acids which are stored in vacuoles
• during the day when light can supply ATP and NADPH , it is used to release CO2 from the organic acids and enter the Calvin Cycle

1. ~ 50% used for fuel for cell. respiration

2. link together to form cellulose

3. excess is stored as starch

• composed of subunits called nucleotides
• composed of 3 parts: sugar, phophate, nitrogenous base

• composed of DNA + proteins (histones)
• heterochromatin: highly condensed, rarely expressed --> when all jumbled? 
• euchromatin: condensed during division, expressed (actively transcribed)

• centromere: condensed region of chromosome
• telomere:region of repetitive DNA sequences at end of chromosome
• kinetochore: disc shaped protein that connects to the spindle fibers
• sister chromatids: when DNA is duplicated, creates these, held together at centromere, pulled apart in mitosis

• nuclear division
• separated into 5 stages: prophase, prometaphase, metaphase, anaphase, telophase
• M phase: mitosis and cytokinesis

• producers of the environment, do not eat anything derived from other living things, produce organic molecules from CO2
• photoautotrophs: plants

• occurs mostly in leaves of plants, in chloropasts to be specific--which are in mesophyll cells (tissue on interior of cell)
• CO2 enters the leaf, and O2 exits throught stomata--microscopic pores
• water enters plants throught the roots and delivered to leaves thru veins
• light energy absorbed by chlorophyll which drives synthesis of organic molecules

• each has a characteristic reaction-center complex, II is known as P680 because it absorbs 680 nm wavelength the best, I is known as P700

• flow of electrons through the photosystems --> key of energy transformation
• 1. as light strikes pigment molecule of PS II, an electron is excited to higher energy level, as fall back to ground level another near pigment molecule is excited --> continues until P680 level is reached in chlorophyll a 
• 2. this electron is transferred from P680 to primary electron acceptor --> P680+
• 3. enzyme catalyzes splitting of water molecule --> 2 H+, 1 O2-, electrons supplied to the P680+ replacing the electrons transferred to the primary electron acceptor, H+ ions transferred to thylakoid lumen --> (provides proton gradient for chemiosmosis), O2- reacts with another O to form O2
• 4. the photoexcited electrons are transferred from PS II to PSI via electron transport chain --> 5. the fall of electrons down energy levels provides energy for synthesis of ATP
• 6. same steps for the P700 clorophyll
• 7. photoexcited electrons pass from primary electron acceptor of PS I down a second electron transport chain to protein ferredoxin (does not produce ATP)
• 8. NAD+ catalyzes the transfer of electrons from Fd to NADP+, 2 electrons required for reduction to NADPH

• uncontrolled cell growth, caused by damage to DNA--mutations --> errors during replication and mitosis
• carcinogens
• viruses-- ~15% of cancers

• genes involved in growth and differentiation
• RTKs, GTPases, growth factors, transcription factors

• genes that when mutated or overexpressed can contribute to turning a normal cell to cancer cell

• mutation to protein structure --> increase in activity or loss of regulation
• increase concentration of proteins --> increase in gene expression, stability, and gene duplication
• chromosomal translocation --> expression in wrong cell at wrong time

• genes which has repressive effect on regulation of cell cycle, promote apoptosis
• this gene is mutated in ~50% of cancer cells

• release of CO2, generates no ATP--uses ATP, decreases photosynthetic output
• neutralizes damaging components of the light cycle

• reproductive cells, contain 23 chromosomes
• the sperm and egg