Photosynthesis and Photosynthesis and Cellular RespirationCellular Respiration

How do cells obtain organic compounds for energy?

Heterotrophs: Cannot make their own food Autotrophs: Can make their own food

– Photoautotrophs: Use energy from the sun (photosynthesis) to produce organic compounds (glucose)

Plants, algae and some bacteria

– Chemoautotrophs: Use energy stored in inorganic compounds (chemosynthesis) to produce organic compounds

Some bacteria found at the hydrothermal vents of the seafloor

Photosynthesis

Method of converting light energy from the sun into chemical energy that cells can use – Divided into the light-dependent and light-independent

reactions

Photosynthesis takes place in chloroplasts– The parts of a chloroplast are as follows:

Thylakoids- disk-shaped structures that contain the pigment chlorophyll (absorbs the sunlight)

Grana- A stack of thylakoidsStroma- Liquid between grana

Draw a Chloroplast

Overall Photosynthesis Reaction

6CO2 + 6 H2O + light energy → C6H12O6 + 6O2

•On the left of the arrow are the reactants (the components that “react” together).•On the right of the arrow are the products. •Identify how a plant obtains the reactants.

Light-dependent Reactions

Chlorophyll (in thylakoids) absorbs the light energy– Plants have 2 types: Chlorophyll A and Chlorophyll

B Water molecules are split apart producing H and

O2

Electrons flow throughout the thylakoid membrane (electron transport chain)

Energy compounds ATP and NADPH are produced

Light-independent Reactions (Dark Reactions)

Occur in the stroma ATP and NADPH from the light reactions are

used to fuel the break down of CO2 and the reassembling of the atoms to produce glucose.

This reassembling is called “carbon fixation”. Carbon fixation occurs in a series of reactions

called the Calvin Cycle.

Photosynthesis Practice

You and a partner need:– 6 orange circles = C– 12 blue triangles = H– 18 pink squares = O– 1 large green oval = thylakoid– 1 small green rectangle = ATP– 1 small green rectangle = NADPH– 1 yellow circle = sun

Getting energy out of food

Plants and animals both use glucose from photosynthesis for cell fuel.

Glucose (or other carbs), proteins, and fats are not a form of energy that our cells can use.

Cellular respiration converts glucose into a usable energy form (ATP) for cells.

Cellular Respiration Overview

The reactions of cellular respiration occur the same way in plants and animals.

Overall Reaction:

C6H12O6 + 6O2 → 6CO2 + 6H2O

How is this compared to the photosynthesis equation?

Glycolysis

Glycolysis is the first process of cellular respiration.

It occurs in the cytosol. Glucose (C6H12O6) is partially broken down to

produce 2 pyruvate (C3H3O3) compounds This process yields 2 ATP and 2 NADH for every

glucose molecule.

Aerobic Cellular Respiration

Oxygen required=aerobicAerobic respiration follows glycolysis. It occurs in the mitochondria.There are 2 main parts to aerobic

respiration:– Kreb’s Cycle– Electron Transport Chain

Kreb’s Cycle

Completes the breakdown of glucose– Takes the 2 pyruvate (C3H3O3) and completely

breaks them down.– The carbon and oxygen atoms of pyruvates

end up in CO2 and H2OThis is where the CO2 that we exhale is produced!

– 3 NADH and 1 FADH2 and 2 ATP get produced

Electron Transport Chain

Here is where most of the energy is produced! Electron flow ultimately produces 32 ATP! The oxygen that we inhale is the electron

acceptor at the end of the ETC. This acceptance of electrons is what produces the ATP.

Photosynthesis

Cellular Respiration

Cellular Respiration Practice

You and a partner need:– 5 NADH (green)– 4 ATP (red)– 1 FADH2 (green)–

1 mitochondria (blue)

Anaerobic Cellular Respiration

Some organisms (some bacteria) thrive in environments with little or no oxygen

No oxygen used= anaerobic Anaerobic organisms experience anaerobic cellular

respiration after glycolysis. This produces NO ATP! Depending on the type of cell, the end products of this

are alcohol or lactic acid.

Energy Tally

Anaerobic organisms can’t be too energetic but are important for global recycling of carbon

  Aerobic AnaerobicGlycolysis    

Kreb’s Cycle 

 

Electron Transport Chain 

 

Total ATP per glucose