ATP, Photosynthesis, and Respiration

ENERGY IN A CELL

Life on Earth depends on the flow of energy:

• Respiration is one way living things get energy

• Photosynthesis is another way

• First we must look at cell energy… what is it???

ENERGY is the ability to do work

• There are different states of energy: – kinetic or potential

• There are different forms of energy:– heat, mechanical, chemical, nuclear,

electromagnetic

Your cells get CHEMICAL energy from foods eaten.

• Cells will store and release the energy as the body needs it

• The storage molecule is known as ATP

• ATP: Adenosine TriPhosphate

– molecule that stores and releases energy for a cell’s functioning

• Energy for a cell comes from braking off a phosphate molecule… NOT directly from food itself

• Energy is stored by adding a phosphate molecule to a ADP (Adensosine DiPhosphate) molecule to create an ATP molecule

Cells use energy to maintain HOMEOSTASIS

• Homeostasis is balance of molecules inside and outside the cell

• Energy is also used for:– enzymes– building cell or body parts– eliminating waste– transporting molecules– basically, for EVERYTHING!!

PHOTOSYNTHESIS

• Photosynthesis is a process where plants trap the sun’s energy to create food (carbohydrates) for itself (ENERGY!!)

• Plants are autotrophs; they have the ability to make their own food

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The process of photosynthesis:

• Chemical formula for photosynthesis:– 6CO2 + 6H2O + E ----> C6H12O6 + 6O2

http://www.physicalgeography.net/fundamentals/9l.html

• The E is light energy from the sun

• This light energy is changed to chemical energy inside the chloroplast of the plant cell. The energy is stored to help make food. (also known as the LIGHT REACTIONS)

Steps to the Light Reactions:• Light from sun strikes chlorophyll, and an electron

(e-) aborbs energy• The e- leaves chlorphyll and is passed along other

molecules called the e- transport chain• As they travel the e- transport chain, extra energy

is stored in the plant as ATP

Steps to the Light Reactions Continued:• Once the e- is gone, the chlorophyll picks up and

splits H2O (called photolysis)

• O2 is given off as waste (humans use!)

• H+ and O- ions are used in the Calvin cycle• http://www.phschool.com/science/biology_place/

biocoach/photosynth/calvin1.html

The H from H2O and the C from the CO2 are used in the Calvin Cycle to produce the food molecules (carbos)

• CO2 enters plant through stems and leaves

• CO2 is changed to glucose (carbos)

• Plant uses the glucose (carbos) to keep surviving

• Sometimes the plant will undergo CHEMOSYNTHESIS instead of photosynthesis if no light is present

• Animals use the plant (source of glucose or carbohydrates) for ENERGY

6CO2 + 6H2O + E ----> C6H12O6 + 6O2

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6CO2 + 6H2O + E ----> C6H12O6 + 6O2

• The 6CO2 comes from aerobic respiration (the air animals breathe out) and the atmosphere

• The 6H2O comes from the rain, soil, urine from animals

• The C6H12O6 are carbohydrates, or food for the plant (animals eat this by eating the plant!)

• The 6O2 is a waste product from the light reactions; plants don’t want but humans do!