Big Ideas
Cellular Respiration and Photosynthesis

Cellular respiration is the process by which the chemical energy of "food" molecules is released and partially captured in the form of ATP. Carbohydrates, fats, and proteins can all be used as fuels in cellular respiration, but glucose is most commonly used as an example to examine the reactions and pathways involved.

In glycolysis, the 6-carbon sugar, glucose, is broken down into two molecules of a 3-carbon molecule called pyruvate. This change is accompanied by a net gain of 2 ATP molecules and 2 NADH molecules.

The Krebs (or Citric Acid) cycle occurs in the mitochondria matrix and generates a pool of chemical energy (ATP, NADH, and FADH 2 ) from the oxidation of pyruvate, the end product of glycolysis. Pyruvate is transported into the mitochondria and loses carbon dioxide to form acetyl-CoA, a 2-carbon molecule. When acetyl-CoA is oxidized to carbon dioxide in the Krebs cycle, chemical energy is released and captured in the form of NADH, FADH 2 , and ATP.

The electron transport chain allows the release of the large amount of chemical energy stored in reduced NAD + (NADH) and reduced FAD (FADH 2 ). The energy released is captured in the form of ATP (3 ATP per NADH and 2 ATP per FADH 2 ). The electron transport chain (ETC) consists of a series of molecules, mostly proteins, embedded in the inner mitochondrial membrane.

The glucose required for cellular respiration is produced by plants. Plants go through a process known as photosynthesis. Photosynthesis can be thought of as the opposite process of cellular respiration. Through two processes known as the light reactions and the dark reactions, plants have the ability to absorb and utilize the energy in sunlight. This energy is then converted along with water and carbon dioxide from the atmosphere into glucose and oxygen. Since this is the opposite process of cellular respiration, plants and animals are said to have a symbiotic relationship. This means that plants and animals live together and benefit from each other. When humans and animals breath, they take in oxygen and give off carbon dioxide. This carbon dioxide is taken up by plants and oxygen is given off through photosynthesis. There is an equilibrium of oxygen and carbon dioxide created between animals and plants. Without one, the other would not survive for long.




Plants at home

We need oxygen to survive

We exhale CO2

When we exhale on a piece of glass we can see moisture

saw mom water the garden

eat a salad for lunch

eat chicken for dinner

Energy Packet

Respiration Boards

Photosynthesis Boards

Plants produce sugar by using the energy they harvest from sunlight, water, and CO2 form the air

My muscles are sore after lifting weights

I breath heavy when I run

Plants use my CO2 I breath out and I use the O2 that plants give off when the make sugar

I get tired when I do not eat for a long time

plants die when they do not get water


Respiration (Anaerobic and Aerobic)


B2.4e - Explain how cellular respiration is important for the production of ATP (build on aerobic vs. anaerobic)

B2.5D - Describe how individual cells break down energy rich molecules to provide energy for cell functions

B3.1C - Recognize the equations for photosynthesis and respiration and identify the reactants and products for both.

B3.1B - Illustrate and describe the energy conversions that occur during photosynthesis and respiration.

L3.2A - Describe common relationships among organisms and provide examples of producer/consumer, predator/prey, or parasite/host relationship.

B2.5f - Relate plant structures and functions to the process of photosynthesis and respiration.

B2.1A - Explain how cells transform energy (ultimately obtained from the sun) from one form to another through the processes of photosynthesis and respiration. Identify the reactants and products in the general reaction of photosynthesis.

B3.1f - Summarize the process of photosynthesis.

B2.1B - Compare and contrast the transformation of matter and energy during photosynthesis and respiration.


Andrew File System Retirement

Andrew File System, which hosts this address, will be ending service by January 1, 2021. Learn about the retirement process, managing your existing files, and alternative services at the Andrew File System Retirement Information Page.