Notes

Cellular Work is Powered by ATP
ATP is the energy currency of the cell
ATP - Adenosine Triphosphate
*Provides energy for a wide range of reactions (Active cell processes)
ATP donates energy to reactions via phosphorylation
Phosphorylation: a phosphate is transferred, from ATP to some other molecule
Nutrient molecules provide the energy to produce ATP
Cell Respiration: The process of transferring energy from nutrient molecules to ATP
*Glucose is the primary nutrient molecule for life
*Energy must be released from nutrients and moved to ATP before it can be used by a cell

Energy conversion in cells
Converting energy from nutrients to ATP involves exergonic and endergonic
Potential energy: Stored energy (Unused batteries)
Kinetic energy: active or released energy (Batteries in use) - does cellular work
*Exergonic reactions release energy (like in kinetic)
*Endergonic reactions absorb energy (box up potential energy like potential energy)
Cells couple exergonic and endergonic reactions
*Thus some is absorbed into ATP
*Energy released by ATP can be used by the cell
Cell respiration is a biochemical pathway that transfers energy from nutrients to ATP
Nutrients -> ATP -> Cell needs

Pathways of photosynthesis
Light dependent reactions - capture light energy and convert it to ATP and NADPH -> carries energy -> light independent reactions -> Uses energy -> makes sugar
Sunlight is made of photons carrying energy
*Light is a small part of electromagnetic spectrum
*Photons are particles of light that travel in waves
*Different wavelengths carry different amounts of energy ( The shorter the waves the more the energy)
Photosynthetic organisms can capture light energy
Light energy is then converted to chemical energy
*In plants, sugars such as glucose are the final products

TROPISM
An organism's trophic level indicates how it acquires its organic material (carbon)
*some things make their own, other things to eat
Autotrophs make their own organic materials
*Plants and algae are autotrophs
Heterotrophs acquire carbon by eating other organisms
*All animals are heterotrophs
Autotrophs are the cornerstone of ecosystems

Photosynthesis occurs in chloroplasts
Inner membrane is organized into thylakoids
Within thylakoid membranes are many protein chains called electron transport chains (ETC)
*So called because they transport electrons
-Phosphates - Electrons - Protons } carry energy
The ETCs capture some energy from photons of light
*This energy is transferred to ATP and NADPH
* O2 (molecular oxygen) is released as a byproduct
ATP and NADPH are used to remove C from CO2
*The C is used to produce a monosaccharide

REDOX reaction
Redox = reduction/oxidation
Involves moving electrons around
*Electrons carry energy, hence it is energy transfer
In reduction, a molecule gains electrons
Reductions: e- are gained so the molecule becomes more negative
Oxidation: e- are lost so the molecule becomes more positive
In oxidation, molecules lose electrons
In biology, reduction is identified by where the H goes
NADP + H ---> NADPH
Oxidized ---> Reduced

ELECTRON ACCEPTORS
Electron acceptor: Oxidizing agents - molecules that can GAIN electrons and move them from place to place
Two molecules, NAD+ and NADP+, are common electron acceptors in organisms
*Electron acceptors are oxidizing agents because after redox the molecules they interact with are oxidized
*After redox, the oxidizing agents are reduced
NAD+ and NADP+ are the oxidized for (+ = OXIDIZED/ withOUT the H is ALWAYS oxidized)
NADH and NADPH are the reduced form (no charge or negative charge is the reduced form/ with H is ALWAYS the reduced form)

THE FIRST SET OF REACTIONS
Light dependent reactions
-Require light in order to occur
-The goal is to transfer light energy to ATP and NADPH
-Light energy excites chlorophyll molecules
Chlorophyll is the molecule that absorbs light energy and starts the ETC
^*Chlorophyll loses electrons to ETC
The ETC get replacement electrons from H2O
*In the process, H+ and O2 are produced
*O2 is used in respiration or released to atmosphere
*NADP+ is reduced to produce NADPH
*H+ are used as fuel to produce ATP
***NADP+ is the final electron acceptor***

Electron Transport and chemosis
Electrons travel through the enzymes of the ETC
*As they travel through the electrons lose energy
*In some cases, electrons exit through the ETC and reduce NADP
Energy from ETC moves from H+ across the membrane
*Doing the produces a concentration gradient
*H= will then diffuse down their concentration gradient
*But they can only do so through ATP Synthase
Chemiosmosis occurs when H+ diffuse through the ATP synthase and ATP is produced in the process

THE SECOND SET OF REACTIONS
The Calvin Cycle
Also called the light independent reactions
The goal is to use ATP and NADPH to produce sugars
*Sugars are require carbon as they are organic
**The carbon originates in CO2
Glucose is a common end product of Calvin cycle
Glucose can be made into starch
*Used for energy storage
Fatty acids and amino acids can be produced also
Three groups of reactions:
*CO2 fixation - CO is added to the molecule ribulose biphosphate (RuBP) to produce an intermediate (C6)
CO2 reduction - the C6 is broken in two (C3) molecules
*ATP and NADPH are used to remove one C from the molecules
*One molecule of glyceraldehyde 3-phosphate (G3P; a sugar) is made for every 3 molecules of CO2 that enter
RuBP regeneration - ribulose biphosphate (C5) is regenerated from many of the intermediates
*RuBP + CO2 begin the cycle again
C6H12O6 = Glucose
Types of photo synthesis