AP Bio: Cellular Respiration and Photosynthesis

energy is stored in

organic molecules (carbohydrates, lipids, proteins)

autotrophs/producers

make carbohydrates via photosynthesis

heterotrophs/consumers

break down carbohydrates to produce ATP

photosynthesis energy pathway

endergonic (requires energy via light); anabolic pathway

cellular respiration energy pathwat

exergonic (releases energy via ATP and heat); catabolic pathway

endotherms

heat comes from within, must consume large amounts of food to generate a lot of heat; high rate of metabolism

ectotherms

heat comes from outside the body; lower rate of metabolism

homeotherms

want to maintain homeostasis for their body temperature

poikilotherms

body temperature varies widely

how energy is moved

electrons carry energy with them, and that energy is stored in another bond, released as heat, or harvested to make ATP; electrons move as part of an H atom

Oxidation

adding O, removing H; loss of electrons; exergonic (releases energy)

Reduction

removing O, adding H; gain of electrons; endergonic (stores energy)

why is ATP important

bond between second and third phosphates is high energy; when broken, energy is released and ADP forms

phosphorylation

when a phosphate group from ATP is added to another molecule, transferring the energy to that molecule

glycolysis reactants

1 Glucose, 2 NAD+, 2 ADP

glycolysis net products

2 pyruvate (3-C), 2 NADH, 2 ATP (requires 2 ATP but produces 4, so net of 2), 2H2O

glycolysis

breakdown of glucose by enzymes; can occur with or without Oxygen

glycolysis location

cytosol (cytoplasm)

steps of glycolysis

1. endergonic energy investment: glycolysis is split into 2 G3P molecules

2. exergonic energy payoff: G3P is oxidized and makes NADH from NAD+, forms pyruvate, intermediate PEP donates P to make ATP via substrate-level phosphorylation

fermentation

keeps glycolysis going by regenerating NAD+; no Oxygen needed

fermentation products

either ethanol and CO2, or lactate; also produces 2 ATP

fermentation is performed by

obligate anaerobes, facultative anaerobes

respiration

release of energy from breakdown of food with O2 as final electron acceptor

fermentation location

cytosol/cytoplasm

respiration locatiobn

mitochondria

respiration is performed by

obligate aerobes and facultative anaerobes (done with a different electron acceptor)

lactic acid fermentation

done by fungi, bacteria, human muscle cells; used to make cheese, yogurt, acetone, methanol; once O2 available, lactate is converted back to pyruvate by the liver

ethanol fermentation

done by bacteria and yeast; used in brewing, winemaking, baking (e.g. makes bread rise); over time, ethanol kills the bacteria/yeast that does it

pyruvate oxidation location

mitochondrial matrix

pyruvate oxidation reactants

2 pyruvate, 2 NAD+, 2 CoA

pyruvate oxidation products

2 Acetyl CoA, 2 NADH, 2 CO2

Krebs Cycle location

mitochondrial matrix

Krebs Cycle reactants

2 Acetyl CoA, 6 NAD+, 2 FAD2+

Krebs Cycle products

2 ATP, 6 NADH, 2 FADH2, 4 CO2 (bc happens twice, once for each Acetyl CoA)

Krebs Cycle importance

glucose has been fully oxidized; some substrate-level phosphorylated ATP; mostly, makes lots of electron carriers

Krebs cycle product that is remade

Oxaloacetate (4C) combined with Acetyl CoA (2C) to make Citrate; after losing 2C via CO2, turns back into Oxaloacetate to redo process

Electron transport chain reactants

10 NADH, 2 FADH2, O2 (as final electron acceptor)

Electron transport chain process

H taken off NADH and FADH2; its electrons = stripped and passed to and from electron carriers in the ETC; H+ pumped across inner mitochondrial membrane (to intermembrane space) for ATP synthesis

ETC electron carriers

each carrier is more electronegative than the previous, so each step is exergonic and releases heat; final electron acceptor is O2 which creates water

ETC ATP Synthase

Facilitated diffusion of H+ through ATP Synthase creates ATP through oxidative phosphorylation

chemiosmosis

diffusion of ions across a membrane

oxidative phosphorylation

phosphorylation from energy released during oxidation of an electron donor

where could other carbohydrates enter cellular respiration

as sugars in the beginning of Glycolysis

where could fats enter cellular respiration

glycerol will enter as a part of G3P, fatty acids will enter as a part of Acetyl CoA

where could proteins enter cellular respiration

proteins will be broken into amino acids, then the amine groups will be taken off; the side groups will be used to form enzymes for pyruvate, Acetyl CoA, or in the Citric Acid cycle

photoautotrophs

use light energy to make organic molecules

chemoautotrophs

use chemicals in the environment to make organic molecules

mesophylll

middle of the leaf, where chloroplasts are usually found

stomata

pores in leaf where CO2 enters and O2 exits

thylakoids

flat green "pancakes" that store chlorophyll and collect energy for light reactions

grana

stacks of thylakoids

stroma

fluid that surrounds the thylakoids, in which the Calvin Cycle takes place; contains ribosomes and chloroplast DNA

overall redox reaction

water is split -> its electrons are transferred with H+ to CO2 -> sugar is formed

photosystem

cluster of pigment molecules bound to proteins, along with a primary electron acceptor

chlorophyll-a

blue/green pigment that converts light to chemical energy; main pigment in light reactions

chlorophyll b

yellow/green pigment that transfers energy to chlorophyll-a; allows plants to absorb greater amounts of light

carotenoids

yellow/orange pigment for photoprotection, which broadens color spectrum for photosynthesis

photoprotection

dissipating excess light energy

Photosystem II best wavelength

680nm

Photosystem II reactants

Light, ADP

Photosystem II products

ATP

Photosystem I best wavelength

700nm

Photosystem I reactants

Light, NADP+

Photosystem I products

NADPH

Photophosphorylation

uses energy of sunlight by PSII to create ATP from ADP, by pumping H+ into the interior of the thylakoid, and having ATP synthase create ATP as H+ diffuses back out through the thylakoid membrane

Non-cyclic Photophosphorylation

Enough ATP is created to cover Calvin Cycle; so, PSII generates energy as ATP and PSI generates reducing power as NADPH

Cyclic Photophosphorylation

Calvin Cycle requires more ATP than is made during light reactions; so, electrons are cycled back to ETC to make more ATP but no new NADPH is made

Light reactions location

thylakoid membrane

Calvin Cycle location (C3 and CAM)

Stroma

Three phases of the Calvin Cycle

carbon fixation, reduction, and regeneration

CC Carbon Fixation process

CO2 is fixed into a carbohydrate

CC Carbon fixation reactants

3 RuBP (5C each), 3 CO2 (1C each), Rubisco (enzyme)

CC Carbon fixation products

6 3-PGA (3C each)

CC Reduction reactants

6 ATP, 6 NADPH

CC Reduction products

6 G3P (3C each), 6 ADP and 6 NADP+ (goes back to light reactions)

CC Reduction process

ATP and NADH are oxidized, and 3-PGA is reduced to make G3P

CC Regeneration process

1 G3P (3C) leaves the cycle as a product and the other 5 (3C each, 15C total) are used to regenerate 3 RuBP (5C each. 15C total); entire Calvin Cycle must happen twice to create 1 molecule of glucose

G3P

end product of the Calvin Cycle; intermediate to make other molecules such as glucose, lipids, amino acids, or nucleic acids

C3 plants

Calvin Cycle ends in production of G3P; on hot, dry days, if CO2 intake reduced, uses photorespiration

Photorespiration

plants partially close stomata to try and conserve water, -> reduction of CO2; thus, Rubisco binds Oxygen instead of CO2 which does not produce sugars

C4 plants

Makes a 4C molecule instead of a 3C molecule in the mesophyll; then, has Calvin Cycle occur in bundle sheath cells

CAM plants

at night, plants collect CO2 and store in mesophyll as organic acid; during day, plants fully close stomata and run Calvin Cycle from CO2 released from stored organic acids

CAM plant examples

cacti, pineapples, succulents

CAM Calvin Cycle location

mesophyll

C4 Calvin Cycle location

bundle sheath cells