Photosynthesis & Cellular Respiration Review

Photosynthesis

• Autotrophs and Their Role:

  • Autotrophs are organisms that produce their own food, serving as primary producers in ecosystems.

• ATP / ADP:

  • ATP (adenosine triphosphate) is the main energy currency of the cell.

  • ADP (adenosine diphosphate) is formed when ATP releases energy by losing a phosphate group; ADP can be converted back to ATP.

• NADPH / NADP+:

  • NADPH is a reducing agent used in photosynthesis to carry high-energy electrons.

  • NADP+ is the oxidized form of NADPH.

• Overall Goal of Photosynthesis:

  • To convert light energy into chemical energy in the form of glucose.

• Light Energy:

  • Light energy can be reflected, transmitted, or absorbed when it hits an object.

• Color Perception:

  • The color we see is the wavelength of light that is reflected by an object.

• Wavelength Energy Use:

  • Plants use specific wavelengths of light (primarily red and blue) for photosynthesis, as shown in wavelength absorption graphs.

• Chloroplast:

  • The organelle in plant cells where photosynthesis occurs.

• Chlorophyll:

  • The pigment in chloroplasts that absorbs light energy.

• Equation for Photosynthesis:

  • $6CO<em>2 + 6H</em>2O + {Light Energy} \rightarrow C<em>6H</em>{12}O<em>6 + 6O</em>2$

Light-Dependent Reactions

• What Happens:

  • Light energy is absorbed by chlorophyll, water is split, and ATP and NADPH are produced.

• Point:

  • To convert light energy into chemical energy (ATP and NADPH).

• What You Get:

  • ATP, NADPH, and oxygen ($O_2$).

Calvin Cycle

• Carbon Fixation:

  • $CO_2$ is incorporated into organic molecules.

• What Happens:

  • ATP and NADPH are used to convert $CO_2$ into glucose.

• Point:

  • To synthesize glucose from $CO_2$.

• What You Get:

  • Glucose ($C<em>6H</em>{12}O_6$).

Photosynthesis / Leaf Chad Lab

• Interpretation:

  • Understand how factors like light intensity and $CO_2$ concentration affect the rate of photosynthesis.

Photosynthesis & Cellular Respiration

• Recognition:

  • Distinguish between photosynthesis and cellular respiration based on their equations, inputs, and outputs.

• Comparison:

  • Photosynthesis produces glucose and oxygen, while cellular respiration consumes glucose and oxygen to produce ATP, water, and carbon dioxide.

• Plants Do Both:

  • Plants perform both photosynthesis and cellular respiration.

Cellular Respiration

• Heterotrophs:

  • Organisms that obtain energy by consuming other organisms.

• Equation for Cellular Respiration:

  • $C<em>6H</em>{12}O<em>6 + 6O</em>2 \rightarrow 6CO<em>2 + 6H</em>2O + {ATP}$

• NADH / NAD+ & FADH2 / FAD:

  • NADH and FADH2 are electron carriers.

  • NAD+ and FAD are their oxidized forms.

Glycolysis

• What Happens:

  • Glucose is broken down into pyruvate.

  • It is anaerobic(Does not need oxygen), and occurs in the cytoplasm of the cell, yielding a small amount of ATP and NADH as energy carriers.

• Point:

  • To produce ATP and NADH.

• What You Get:

  • Pyruvate, ATP, and NADH.

Aerobic Respiration

Krebs (Citric Acid) Cycle

• What Happens:

  • Pyruvate is converted into acetyl-CoA, which enters the Krebs cycle, producing ATP, NADH, and FADH2.

• Point:

  • To further oxidize glucose and produce more ATP, NADH, and FADH2.

• What You Get:

  • ATP, NADH, FADH2, and $CO_2$.

Electron Transport Chain

• What Happens:

  • NADH and FADH2 donate electrons, creating a proton gradient that drives ATP synthesis.

• Point:

  • To produce a large amount of ATP.

• Efficiency of Aerobic Respiration:

  • About 36-38 ATP molecules are produced per glucose molecule.

Cellular Respiration Lab

• Interpretation:

  • Understand how factors like temperature and glucose concentration affect the rate of cellular respiration.

  • Bromthymol blue turns yellow in the presence of $CO_2$, indicating respiration.

Fermentation

• Point of Fermentation:

  • To regenerate NAD+ so glycolysis can continue in the absence of oxygen.

• Anaerobic:

  • Occurs without oxygen.

Lactic Acid Fermentation

• What Happens:

  • Pyruvate is converted into lactic acid.

• Who Does This and When:

  • Humans (muscle cells during intense exercise).

• Benefits for Humans:

  • Allows for short bursts of energy production when oxygen is limited.

Alcoholic Fermentation

• What Happens:

  • Pyruvate is converted into ethanol and $CO_2$.

• Who Does It and When:

  • Yeast. This process occurs during anaerobic respiration, specifically when oxygen is scarce, allowing yeast to generate energy through fermentation.

• Benefits for Humans:

  • Used in brewing and baking.

Carbon Cycle

• Forms of Carbon Molecules & Locations:

  • $CO_2$ in the atmosphere, organic molecules in living organisms, fossil fuels underground.

• Flow of Carbon Through the Ecosystem:

  • Photosynthesis, respiration, decomposition, combustion.

• How Humans Alter the Carbon Cycle:

  • Burning fossil fuels, deforestation, and industrial processes increase atmospheric $CO_2$ levels.