CHAPTER 4: Cells and Energy
4.1 Chemical Energy and ATP
Chemical Energy
· the chemical NRG used for most cell processes is carried by ATP
o some of these processes include building molecules and moving materials
· Carbon-based molecules store NRG in their bonds
· Carbohydrates and Lipids are the most important NRG sources
What is ATP?
· adenosine triphosphate
How can we get NRG from ATP?
· By breaking the bonds
· ATP has three phosphate groups
· When one phosphate group is removed, NRG is released
· ATP is now ADP—adenosine diphosphate
adenosine triphosphate
adenosine diphosphate
HOW Does Food provide NRG?
· The food you eat is supplying the energy needed to convert ADP back into ATP.
· Food molecules store chemical NRG in their bonds. When food is digested, the bonds are broken and NRG is released.
· Carbohydrates are most commonly broken down to make ATP.
· Lipids store the most amount of ATP
Photosynthesis
· Molecules break down sugars to produce ATP, but where do these sugars come from?
Answer: PHOTOSYNTHESIS
Thus, most all of life is dependent upon photosynthesis.
Producers
· plants, bacteria and protists convert the sun’s NRG into usable chemical NRG: they can photosynthesize—capture the sun’s NRG to make sugars that store chemical NRG
· Producers either directly or indirectly supply all organisms with NRG
o Wolf eats the rabbit, which eats plants, which get NRG from the sun
Plants have Chlorophyll
· chlorophyll is a pigment that absorbs sunlight
· chlorophyll absorbs mostly blue and red wavelengths
· chlorophyll is located in the chloroplast
o Most chloroplasts are in leaf cells
o Chloroplasts contain grana and stroma
o Grana- stacks of thylakoids ( where the chlorophyll is)
o Stroma- the fluid that surrounds the thylakoids
1 thylakoid
Stroma grana
The Equation for Photosynthesis:
6CO2 + 6 H2O C6H12O6 + 6 O2
Two steps to PSN:
1. The light-dependant reactions
a. Needs sunlight to work
b. Takes place in the thylakoid membranes
c. The sunlight NRG is absorbed by chlorophyll in the thylakoids
d. The sunlight NRG is changed into ATP and NADPH
e. Oxygen is released as a by-product (a waste product)
2. The light-independent reactions A.K.A. The Calvin Cycle
a. Does not need sunlight to work
b. Takes place in the stroma
c. Six molecules of CO2, ATP, and NADPH enter the cycle; and one molecule of glucose is made
PSN Review
· Photosynthesis takes place mainly in leaves.
· The products of PSN are glucose and oxygen
· Glucose can then be turned into ATP in the process of cellular respiration.
Cellular Respiration
· Takes place in both plants and animals
· occurs in the mitochondria
· breaks down glucose into ATP
THE CHEMICAL EQUATION
C6H12O6 + 6 O 6CO2 + 6 H2O
Two Steps of Cellular Respiration:
1. Glycolysis-- Glucose is changed into Pyruvate
2. If Oxygen is present (aerobic): ATP is made (Krebs cycle)
If No oxygen is present (anaerobic): Fermentation
Fermentation In Animals:
· Pyruvate is changed into lactic acid -- what make your muscles sour, and burn when exercising
Fermentation In Plants:
· Pyruvate is changed into an alcohol
· This produces food products such as breads, yogurt, cheeses,