Photosynthesis & Respiration

What is Photosynthesis?

The process of photosynthesis is a chemical reaction.

It is the most important chemical reaction on our planet.

What do plants need for photosynthesis?

• Water• Carbon dioxide• Light• chlorophyll

What is the equation for the chemical reaction of

photosynthesis?

Describe Photosynthesis• The process of changing light energy to

chemical energy • Energy stored as sugar• Occurs in plants and some algae • Plants need light energy, CO2, and H2O • Takes place in the chloroplasts, using

chlorophyll, the green pigment in plants

What is it like inside a chloroplast?

• All around the chloroplasts are stacks of things called thylakoids.

• The part of the chloroplast that is outside the thylakoids is called the stroma.

• THE CALVIN CYCLE is in the stroma!

What are the two types of reactions in photosynthesis?

1. The first reaction is called light-dependent (occurs in the thylakoids)

2. The second reaction is light-independent (occurs in the stroma)

What do electron carriers do?

• Sunlight makes electrons in the chlorophyll (located in the thylakoids) very excited! They are so excited they have to be carried by a special carrier molecule called NADP+

• NADP+ carries two electrons at a time.• It also grabs an H+ ion, and this turns the

NADP+ into NADPH

What does the NADPH do?

• The NADPH carries the very excited high-energy electrons to reactions in the cell.

• These electrons can be used in making FOOD.

• This is the LIGHT-DEPENDENT Reaction

What is the dreaded Calvin Cycle?

• The Calvin Cycle uses ATP and NADPH from light-dependent reactions to produce high-energy sugars (FOOD)

• The Calvin Cycle is a LIGHT- INDEPENDENT reaction

What are the products of photosynthesis?

• High-energy sugars (FOOD)• oxygen

Why is this important to us?• We cannot make our own food (glucose,

energy), we must get our food from plants.• Plants are the first step in the food chain.• The oxygen released during photosynthesis

is necessary for all living things.

Quiz1) Describe what it’s like inside a chloroplast.2) Why does Hamel say that photosynthesis is

one of the most important chemical reactions on Earth?

3) What happens during the Calvin Cycle?4) What are the products of photosynthesis?5) What is needed for photosynthesis?6) What happens to electrons during

photosynthesis?7) Which happens first, light-dependent reactions

or light-independent ones?8) What does NADP+ do?

What is Cellular Respiration?• Once the energy that was in sunlight is

changed into chemical energy by photosynthesis, an organism has to transform the chemical energy into a form that can be used by the organism.

• Cellular respiration is the process that releases energy by breaking down food molecules in the presence of oxygen.

Describe Cellular Respiration• The breakdown of glucose molecules to

release energy

• Takes place in all living things

• Is a step by step process

Where does cellular respiration happen?

• In the mitochondria of living things.

What is the chemical equation for cellular respiration?

Diagram of the Process

Occurs in Cytoplasm

Occurs in Matrix

Occurs across Cristae

What are the Stages of Cellular Respiration?

• GlycolysisGlycolysis• The Krebs CycleThe Krebs Cycle• The Electron Transport ChainThe Electron Transport Chain

Anaerobic Processes• No oxygen is

required for these processes.

• Includes glycolysis, the breakdown of glucose, and fermentation.

• Some bacteria and yeast are examples of anaerobes.

http://www.biol.vt.edu/research/images/C._perfringens_in_mac._jpg.jpg

http://www.utoronto.ca/greenblattlab/images/a/yeast%201.jpg

Glycolysis• Occurs in the

cytoplasm.• Breaks down glucose

into 2 molecules of pyruvate

• 2 ATP molecules are formed.

The series of reactions in which pyruvate is broken down into carbon dioxide is called the Krebs cycle.

http://www.emc.maricopa.edu/faculty/farabee/BIOBK/enyld1.gif

There’s another cycle?

• Yes. The Krebs cycle.• The Krebs cycle is where energy is

released. Kind of like the Calvin Cycle in reverse…

What happens during the Krebs cycle?

• Energy is freed from the chemical bonds. The excited electrons are FREEE!

• The electrons make ATP.• Carbon dioxide is released.

You get rid of it by exhaling…

Where do the electrons go?

• On the train!• The electrons get to ride the

electron transport train, the Final step in the breakdown of glucose.

• Point at which ATP is produced

What happens to ADP on the train?

• Ions rush back and forth and spin the ADP in circles.

• This creates enough energy to produce three molecules of ATP per molecule of ADP.

• ATP and ADP are special molecules that store energy

Quiz1. Where does cellular respiration take

place?2. What is the chemical equation for

cellular respiration?3. What are the products of cellular

respiration?4. What is the Krebs Cycle?5. What happens during the Krebs Cycle?6. What happens to electrons during

cellular respiration?7. How much ATP is produced from one

molecule of ADP?

Complementary processes• Photosynthesis is an

important part of the carbon cycle.

• The processes of photosynthesis and cellular respiration are complementary processes, meaning they work together to benefit living organisms.

Plants and animals contribute…

• Autotrophs, such as plants, produce glucose using the carbon in carbon dioxide.

• Both autotrophs and heterotrophs, such as grasshoppers that eat plants, use those carbohydrates in cellular respiration.

• Respiration, in turn, produces carbon dioxide.

Energy renewal• Energy captured from

sunlight by photosynthetic organisms is used and released in the cellular respiration of living things.

• The energy that living things use, must continually be renewed through photosynthesis.

• Now create a diagram, that represents the relationship between photosynthesis and cellular respiration (the carbon cycle).

• Diagram must include at least one autotroph and one heterotroph.

• Illustrate and label the stages.• Title: Photosynthesis/Respiration