Cellular Respiration/Photosynthesis Flashcards

Redox Reactions

An oxidation and reduction reaction occurring together. Eg. cellular respiration

Oxidation Reaction

Movement of an electron to a lower energy state. Releases energy (exergonic) and typically coupled with a reduction reaction. Either gaining O, losing H (e-).

Reduction Reaction

Movement of an electron to a higher energy state - reduced molecules have higher potential energy than oxidized molecules. Stores energy (endergonic). Either losing O, gaining H (e-).

Electron Carrier

Molecule that moves electrons by moving H atoms. Eg. NAD+, FAD2+

Cellular Respiration

Conversion of glucose and oxygen into CO2m H2O and ATP. Composed of 4 steps

1. Glycolysis

2. Pyruvate Oxidation

3. Krebs Cycle

4. Electron Transport Chain

Anerobic Respiration

Respiration that is able to occur without O2. Eg. glycolysis

Aerobic Respiration

Respiration that needs O2, occurs in the mitochondria.

Eg. Pyruvate oxidation, krebs cycle, electron transport chain

Mitochondria

Double-membrane organelle where cellular respiration occurs.

1. Cristae

2. Intermembrane Space

3. Matrix

Cristae

Folds on the inner membrane to increase surface area to volume ratio

Intermembrane Space

Fluid-filled space between the two membranes of a mitochondria. Important for setting up the proton gradient for the ETC. Location of pyruvate oxidation, electron transport chain

Matrix

Innermost fluid-filled space. Location of krebs cycle

Glycolysis

Breaking down glucose into “simpler” sugars. Performed by all organisms but very inefficient - starting point of all cellular respiration. Anerobic. Occurs in the cytosol/cytoplasm. 1st half = phosphorylation, 2nd half = energy payoff.

• C6H12O6 → 2 pyruvate + 2 ATP + 2NADH

Phosphorylation

Adding phosphates onto molecules to make them unstable. Used for exothermic reactions because the molecules become easy to split. 1st half of glycolysis → used to destabilize glucose by investing energy

Energy Payoff (Glycolysis pt2)

Production of NADH and ATP. Energy harvesting from glycolysis.

Substrate Level Phosphorylation

Metabolic reaction that produces ATP

Recycling NADH/NAD+

In bacteria: pyruvate converted to ethanol and CO2 (NADH → NAD+)

In animals: pyruvate converted to lactic acid (NADH → NAD+)

• Lactic acid can be converted back to pyruvate to be oxidized in cellular respiration

Pyruvate Oxidation

Pyruvate + NAD+ → CO2 + acetyl-CoA + NADH

• occurs twice per glucose

• Aerobic process

• NAD+ reduced, pyruvate oxidized

Krebs Cycle

Citric Acid Cycle. Occurs in mitochondrial matrix, catabolism of 6C citrate molecule.

• Acetyl-CoA → 2 CO2 + 4 NADH + ATP + FADH2

• Occurs twice for every glucose

• Reduction of energy carriers

• Energy carriers go to ETC

• In total produces 4 CO2, 8 NADH, 2 ATP, 4 FADH2

Electron Transport Chain - Cellular Respiration

Chain of proteins in the inner mitochondrial membrane. Transports e- down ETC by creating H+ gradient to yield ~36 ATP. Only happens with O2 (aerobic respiration). Final e- acceptor in cell respiration is O2 (production of water)

ATP Synthase

Enzyme to set up H+ gradient to turn ADP and Pi → ATP

Chemiosmosis

Movement of H+ across a semipermeable membrane down their electrochemical gradient to produce ATP

Photosynthesis

Process by which plants produce glucose and oxygen from light energy, CO2, and H2O

• CO2 + H2O + light → C6H12O6 + 6O2

  1. Light dependent reaction

  2. Light independent reaction

Light dependent Reaction

Occurs in the thylakoids where solar energy is converted to chemical energy.

1. Photosystem 2

2. ETC

3. Photosystem 1

Photosystem II

Photosystem where e- (excited by light energy) move to “primary e- acceptor” → e- constantly being lost, to replenish, photolysis occurs. Funnels e- into ETC (important for creating concentration gradient)

Electron Transport Chain - Photosynthesis

Movement of e- from PS1 to PS2. Creation of a proton gradient in inner membrane space of chloroplasts. Funnels e- into PS1

Photosystem 1

e- from ETC powers PS1 - “recharging e- after ETC”. Transfers e- into energy carriers (NADPH). Cyclic - e- either get used for NADPH or back to ETC for ATP synthase

Light Independent

Calvin Cycle. Occurs in the stroma, needs the products of the light reaction to drive synthesis (ATP and NADPH).

• Attaching CO2 on to RuBP (5C) to make a 6C with rubisco enzyme

  • Carbon fixation

  • Occurs 6 times to make 2 G3P (1 glucose)

  • Uses energy from carriers to power cycle