Bio Unit 4

Unit 4 Photosynthesis and Respiration



?As we have talked about, our bodies need energy in order to survive

?Every bit of energy our bodies use comes from the sun

?To describe how organisms get their energy, there are two categories:



?Autotrophs ~ organisms that use energy in sunlight to make organic compounds

?Autotrophs convert sunlight into chemical energy in the form of carbohydrates

?This occurs in the chloroplasts (remember that is one difference between plants and animals)

?Example: Plants

?Heterotrophs ~ organisms that CAN NOT make their own energy and must get their energy from food

?Example: US!

?We get our energy by eating food that has carbohydrates made by plants

?Here are some examples of the flow of energy

?A carrot is an autotroph.  It uses the sunlight to create energy for itself through a process called PHOTOSYNTHESIS

?We are heterotrophs, we  eat carrots.  We take the energy that the carrot made for itself.

?We may also eat meat.  Meat comes from cows.  Cows eat grass.  Cows take the grass’s energy, and we take the energy from the grass the cow didn’t use

•We are all Connected



?So the question becomes…how do plants make energy from the sun?

?They do this through a process called photosynthesis

?Photosynthesis ~ process by which light energy is converted to chemical energy (ATP)

?The chemical equation for photosynthesis is

?Sunlight + 6CO2 + 6H2O à C6H12O6 + 6O2


photosynthesis.jpg?Energy+ Carbon Dioxide + Water à Glucose + Oxygen

?In order for photosynthesis to occur it needs:

?Sunlight (energy)

?Carbon Dioxide (CO2)

?Water (H2O)

?Photosynthesis produces:

?Oxygen (O2)

?Glucose (C6H12O6)

?Glucose is a sugar/carbohydrate

?Photosynthesis takes place in the chloroplasts

?Inside the chloropast are disk-shaped structures called thylakoids

?The thylakoid disks contain the pigment chlorophyll which captures the light



?Why is photosynthesis important to us?

?We breathe the oxygen that is given off and we use the glucose for energy that is stored in the plant

?Humans perform a process called cellular respiration

?Cellular respiration ~ the process by which cells produce energy from carbohydrates in the presence of oxygen

?The chemical equation for cellular respiration is:

?C6H12O6 + 6O2 à 6CO2 + 6H2O + ATP


?Glucose + Oxygen à Carbon Dioxide + Water + Energy

c9x6cell-respiration.jpg?In order for cellular respiration to occur it needs:

?Glucose (C6H12O6)

?Oxygen (O2)

?Respiration produces:

?Carbon Dioxide (CO2)

?Water (H2O)

?Energy (ATP)

?The goal of respiration is to make ATP (energy)

?This happens in 3 stages:

?Glycolysis takes place in they cytoplasm and makes 2 ATP

?Krebs cycle takes place in the mitochondria and makes 1 ATP

?Electron transport chain takes place in the mitochondria and makes 34 ATP



?I have mentioned ATP quite a bit today, so what is it?

?ATP stands for adenosine triphosphate

C7_atp_2.GIF?This is important because when ATP is used in chemical reactions, the bonds between the phosphates break giving off a lot of energy

?When the phosphate bonds break, ADP is created

?ADP stands for adenosine diphosphate

?How many phosphates does ATP have?


?How many phosphates does ADP have?