Photosynthesis – The Energy of Life



Photosynthesis – The Energy of Life

Energy is the _ability to do work________

Autotrophs

• Organisms that can capture _energy from sunlight___ or chemicals and use it to produce____ it’s own __food_____ from inorganic compounds

• Also called a __producer_____

• Make their own food - Example __plants______

• Autotrophs synthesize organic compounds (glucose) from inorganic materials (water, sunlight, and carbon dioxide)

Heterotrophs

• An organism that obtains _energy_____ from the __food______ it consumes

• Also called a __consumer___ - Example __humans_______

• Heterotrophs consume pre- formed organic compounds.

Chemical Energy and ATP

• There are different forms of energy (ex. Light, _heat______, electrical, chemical)

• Energy can be _stored__ in the bonds of __chemical__ __compounds______

• Example: Candle burning – the candle (which is made of Carbon and Hydrogen) combines with air (Oxygen) to produce water and carbon dioxide and releases energy in the form of light and heat

ATP and ADP

ATP – Adenosine triphosphate

• One of the principal chemical compounds that living things use to _store energy___

Releasing Energy from ATP

• The characteristics of ATP make it an exceptionally useful molecule that is

_used by all cells____ as their basic energy source____

_______Release of Energy______

ATP ( ADP + Phosphate

3 ( 2 1

• We need ATP (energy) for ___active __ __transport_____

ATP and GLUCOSE

• ATP is not good for storing large amounts of energy

• Glucose (Carbohydrate) can store 90 times the energy of ATP

• ___Cells make ATP from glucose____ ___________

• Organisms make energy readily available by transferring the chemical bond energy of organic molecules to adenosine triphosphate.

Photosynthesis – An overview

___Photosynthesis_____ (light-putting together)

• Process by which plants____ and some other organisms _use_ _light__ energy to power chemical reactions that __convert_____ water and _carbon__ _dioxide___

INTO _oxygen__ and high-energy carbohydrates such as _sugars__ and starches.

• The Photosynthesis Equation

In the presence of LIGHT and chlorophyll

6 CO2 + 6 H2O ( C6H12O6 + 6 O2

Carbon Dioxide + Water ( Glucose + Oxygen

• Photosynthesis uses the energy of __sunlight____ to convert __water___ and _carbon dioxide__ into oxygen and high energy _sugars_ (starches)

• Photosynthesis converts light energy into chemical energy which is stored in the bonds of carbohydrates.

Lights and Pigments

• In addition to water and carbon dioxide, photosynthesis _requires___ light and _chlorophyll___, a chemical compound found in chloroplasts

• Pigment – Green Chlorophyll is a _light absorbing,_ _green____ colored molecule

• Chlorophyll – the principle pigment of plants and other photosynthetic organisms

• Captures _light___ energy to be converted into chemical energy stored in bonds

Why are plants green? They do not absorb _green____ light

The Reaction of Photosynthesis

Light Dependent reactions aka photochemical (light) reactions

• Need light (thylakoids) H2O + Light ( O2

• Occurs in the chloroplast, within the stacked layers of chlorophyll-containing membranes known as grana. The grana contain enzymes that speed up this process.

• Light energy along with other pigments on the grana is used to split the water molecules into hydrogen and oxygen. This process is photolysis (splitting with light). It produces the energy carrying molecule ATP. Atoms of oxygen recombine to form atmospheric oxygen, which is released as a gas. The hydrogen released is transferred to the next step.

Light Independent Reactions (do NOT need light) aka carbon-fixation (dark) reactions

• Calvin Cycle, stroma CO2 ( Sugar

• Combine the released hydrogen atoms with the atoms making up carbon dioxide. A 3- carbon compound, PGAL is created. This compound can synthesize several other compounds like glucose. A stable form of carbon results from this process.

Photosynthesis – Factors Affecting Photosynthesis

1. Dry conditions - Shortage of __water___ (ex. Desert plants and conifers have a waxy coating on their leaves that reduce water loss)

2. Temperature – Must be within a certain range

o _Enzymes__ work at 0 – 35 deg. Celsius, at other temps they become __denatured___ (damaged)

3. _Light__ Intensity

o When light _increases_, photosynthesis __increases___

o When light _decreases, photosynthesis _decreases___

Why do leaves change color in the fall? Some plant leaves contain yellow and red pigments as well as chlorophyll. In the fall, those leaves may become red or yellow.

ANSWER: _Chlorophyll may be broken down by the cooler temperatures or changing light so the green color disappears.

The leaf then shows the remaining color pigments.

Cellular Respiration – Chemical Pathways

Chemical Energy and Food – How much energy is actually present in food?

• One gram of the sugar glucose when burned in the presence of Oxygen, releases 3,811 calories of heat energy

What is a calorie?

• The amount of energy needed to raise the temperature of 1 gram of water 1 Celsius degree Food Labels: 1 Calorie is really 1,000 calories

Glycolysis (lysis = breaking apart)

• First step in releasing the energy of GLUCOSE in which a molecule of glucose is _broken down into two molecules of _pyruvic acid__. This releases a _small_ amount of energy.

Overview of Cellular Respiration (the opposite of photosynthesis)

Cellular Respiration

• Is the process that _releases energy_ by breaking down _food__ molecules in the presence of _oxygen______. This occurs in the mitochondria!!

• Equation:

C6H12O6 + 6 O2 ( 6 CO2 + 6 H2O + Energy

Glucose + Oxygen (Carbon Dioxide + Water + Energy

Glycolysis ( step one of ALL respiration)

• Is a process in which one__ molecule of _glucose___ is broken in half, producing _two__ molecules of pyruvic acid (a 3 Carbon compound)

o Start with 2 ATP ( End with 4 ATP (because of energy released when bonds break)

o Net GAIN ( 2 ATP

Fermentation ( step two of Anaerobic Respiration)

• A process by which cells __release energy in the _absence_______ of oxygen

• Anaerobic – DOES _NOT___ require oxygen

Two Main Types of Fermentation

• Alcoholic Fermentation (Yeast (used to make bread); Wine and Beer)

• Lactic Acid Fermentation (occurs in humans when they exercise)

Alcoholic Fermentation

Equation: Pyruvic Acid + NADH ( Ethyl Alcohol + CO2 + NAD+

Lactic Acid Fermentation

Equation: Pyruvic Acid + NADH ( Lactic Acid + NAD+

• Lactic Acid is produced in your _muscles____ during vigorous exercise when the body cannot _supply__ enough _oxygen____ to the __tissues__.

o Buildup of lactic acid causes a _painful__, _burning____ sensation (stitch)

o Muscles may feel sore

The Krebs Cycle and Electron Transport

AEROBIC – process that requires Oxygen

The Krebs Cycle (Step Two of Aerobic Respiration)

• Second stage of Aerobic Cellular respiration in which _pyruvic__ _acid___ is broken _down____ into carbon dioxide in a series of _energy____ extracting __reactions___.

o Carbon dioxide, NADH, ATP, FADH2

• Includes Electron Transport Chain – a series of __proteins____ in which high-energy _electrons____ are used to convert ADP into _ATP_______.

The total ATP production of Aerobic Cellular Respiration)

Glycolysis ( 2 ATP

Krebs cycle + Electron Transport chain ( 34 ATP

TOTAL ( 36 ATP produced

Waste products of Aerobic Cellular Respiration: _water__ and _carbon dioxide

Energy and Exercise When runners begin a race, how do their bodies obtain energy?

1. Uses ATP____ in muscles

2. New _ATP_____ is made by lactic acid _fermentation___and aerobic cellular __respiration__

3. Body uses all three ATP sources (the stored ATP and ATP produced by lactic acid fermentation can only supply energy for a limited time) NEED Oxygen and glucose to keep up supply of ATP

Quick Energy:

• Lactic Acid -( by product - Getting rid of Lactic acid build-up requires extra _oxygen___ so you breathe__ heavily to get extra Oxygen to your cells

Long-Term Energy

• Your body can break down GLYCOGEN AND FATS to release energy

Comparing Photosynthesis and Cellular Respiration

Photosynthesis:

• Removes (uses) __carbon dioxide_ from the atmosphere (environment)

• Releases _oxygen_____ into the atmosphere (environment)

• Products of photosynthesis are _similar_____ to the reactants of cellular respiration

• This process takes place in green plants_____, algae and some bacteria

• Only occurs in the presence of light

Cellular Respiration:

• Releases _carbon dioxide__ into the environment

• Removes (uses) __oxygen__________

• Products of _cellular respiration are similar to the reactants of photosynthesis

• This process takes place in all ___eukaryotes_____ and some _prokaryotes___

• Happens 24/7 – If you are not respirating you are DEAD

| |PHOTOSYNTHESIS |RESPIRATION |

|FUNCTION | | |

|LOCATION | | |

|REACTANTS | | |

|PRODUCTS | | |

|EQUATION | | |

| | | |

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