PHOTOSYNTHESIS & RESPIRATION

Photosynthesis & Respiration

Modern Biology–Photosynthesis / Chapter

6 –Cellular Respiration /

Chapter 7

Energy for Life Processes

• All organisms need energy to survive– Primary source of energy is the sun.

• Energy is the ability to do work… • Work for a cell includes growth & repair,

active transport across cell membranes, reproduction, synthesis of cellular products, etc.

Most organisms need a constant supply of energy.

Energy can be found in many forms.

Energy from the sun is in the form of light energy.

Energy in food is in the form of chemical energy.

Energy for Life Processes

Humpback whales need a lot of energy to leap into the air.

Energy comes fromthe food that they eat.

How much food doyou think a humpbackwhale can eatin one day?

Energy for Life Processes

How do organisms get this energy from the sun?

–PHOTOSYNTHESIS-process used by plants to convert energy from the sun to food (glucose).–RESPIRATION-process that releases energy in food (glucose) to make energy (ATP).

Energy for Life Processes

Autotrophic – “self-feeding”

• Autotrophs or producers convert sunlight, CO2, and H2O into glucose (their food).– This process is called “PHOTOSYNTHESIS”

• Plants, algae, and blue-green bacteria, some prokaryotes, are producers or autotrophs .

Autotrophs

Plants

Algae & some bacteria

Energy for Life Processes

• Only 10% of the Earth’s 40 million species are autotrophs

• Some other autotrophs use inorganic compounds instead of sunlight to make food; process known as chemosynthesis

• Producers make food for themselves and for heterotrophs or consumers that cannot make food for themselves

Heterotrophic – “other-feeding”

• Animals (including humans) represent heterotrophic organisms.

• Since they cannot make their own food, humans and other heterotrophs must get their complex organic compounds by eating plants or other organisms.

Animals and Fungi

Once you eat something, the food gets broken down into ‘nutrients’, or smaller molecules the cells can use.

Some of these molecules are in the form of sugar (glucose). The bonds that hold these molecules together contain energy.

Photosynthesis & Respiration

Cells “absorb” broken food pieces (macromolecules such as protein, nucleic acid, carbohydrates, lipids). In the form of monomers ( building blocks, such as amino acids, glucose & fructose, nucleotides and some smaller pieces of lipids.).

• Cellular respiration is the process that turns food into ATP, a form of energy that our cells can use.

Photosynthesis & Respiration

Energy for Life Processes

Biochemical Pathways

• Photosynthesis and cellular respiration are biochemical pathways

• Biochemical pathways are a series of reactions where the product of one reaction is the reactant of the next

• Only autotrophs are capable of photosynthesis

• Both autotrophs & heterotrophs perform cellular respiration to release energy to do work

Biochemical Pathways

• In photosynthesis, CO2(carbon dioxide) and H2O (water) are combined to form C6H12O6 (glucose) & O2 (oxygen)6CO2+ 6H2O + energy --> 6O2 + C6H12O6

• In cellular respiration, O2 (oxygen) is used to burn C6H12O6 (glucose) & release CO2(carbon dioxide) , H2O (water) and energy

• Usable energy produced in cellular respiration is stored in the chemical bonds of the molecule adenosine triphosphate or ATP

Biochemical Pathways

Photosynthesis

Cellular Respiration

Biochemical Pathways

PHOTOSYNTHESIS

A series of chemical reactions (light & dark

reactions and the Calvin Cycle) where autotrophs capture light energy to make food (glucose).

Chemical Formula:6CO2 + 6H2O + sunlight C6H12O6 + 6O2•Carbon Dioxide water sunlight glucose and oxygen

Leaves: Photosynthetic Factories

• Photosynthesis requires the green pigment chlorophyll.

• The chemical reactions of photosynthesis occur within the chlorophyll-containing organelles called chloroplasts.

• These are found inside cells in plant leaves and stems.

Chloroplasts - membrane bound organelles found in plant and algae cells that absorb light during photosynthesis

They contain:1. the light absorbing pigments2. enzymes for photosynthesis

Light Absorption in Chloroplasts

Light Absorption in Chloroplasts

• Photosynthetic cells may have thousands of chloroplasts

• Chloroplasts are double membrane organelles with the an inner membrane folded into disc-shaped sacs called thylakoids

Light Absorption in Chloroplasts

• Thylakoids, containing chlorophyll and other accessory pigments, are in stacks called granum (grana, plural)

• Grana are connected to each other & surrounded by a gel-like material called stroma

• Light-capturing pigments are found in the grana.

Light Absorption in Chloroplasts

Light Absorption in Chloroplasts

How do chloroplasts absorb light??

LIGHT:

Light travels as waves & packets called photons Wavelength of light is the distance between 2 consecutive

peaks ortroughs

Light Absorption in Chloroplasts

Sunlight or white light is made of different wavelengths or colors carrying different amounts of energy

A prism separates white light into 7 colors (red, orange, yellow, green, blue, indigo, & violet)

ROY G BIV

These colors are called the visible spectrum

Light Absorption in Chloroplasts

The visible spectrum

Each color in a rainbow corresponds to a different wavelength of electromagnetic spectrum.

Light Absorption in Chloroplasts

When light strikes an object, it is absorbed, transmitted, or reflected

When all colors are absorbed, the object appears black

When all colors are reflected, the object appears white

If only one color is reflected (green), the object appears that color (e.g. Chlorophyll)

Thylakoids contain a variety of pigments –molecules that absorbs light - (green, red, orange, yellow...)

Chlorophyll is themost commonpigment in plants & algae

Chlorophyll absorbsonly red, blue, & violet light

Light Absorption and Pigments

Accessory pigments trap wavelengths of light that can not be absorbed by chlorophyll - help capture more light energy

• Carotenoids – reflect orange, yellow, and brown and absorbs green and blue

• Phycobilins – reflect violet & blue and absorb orange, brown and green

Light Absorption and Pigments

Photosynthesis is not a simple one step reaction but a biochemical pathway involving many steps.

This complex reaction can be broken down into two reactions:

1. light dependent (Photosystem I & II, Electron Transport Chain)2. light independent or dark reactions (The Calvin Cycle)

Overview of Photosynthesis

Overview of Photosynthesis

Overview of Photosynthesis

Plants in hot, dry climates use alternate pathways to fix carbon.

Stomata are small openings on the underside of leaves for gas exchange (O2 & CO2)

Plants also lose H2O through stoma so they are closed during the hottest part of the day

Alternate Pathways

The Calvin cycle is the most common pathway used by autotrophs, called C3 Plants.

C4 plants have a clever way of fixing CO 2 during the hottest part of the day when their stomata are partially closed. C4 plants include corn, sugar cane and crabgrass CAM plants include cactus & pineapples

CAM plants open their stomata at night and close during the day so CO2 is fixed at night. During the day, the CO2

is released from these compounds and enters the Calvin Cycle.

Alternate Pathways

Sunlight

CarbonDioxide CO2

Water H2O

Oxygen O2

Leaves: Photosynthetic Factories

PHOTOSYNTHESIS

REMEMBER:This all-important photosynthetic reaction can be summarized by the following chemical equation:

6CO2 + 6H2O + energy (sun) C6H12O6 + 6O2

Factors Affecting Photosynthesis• As with any chemical

reaction, the reactions of photosynthesis can occur at different rates.

• The factors that affect the rate at which photosynthesis occurs are temperature, light intensity, CO2 concentration, availability of water, and the presence of certain minerals.

Factors Affecting PhotosynthesisFor example:Light and CO2: eventually the rate of photosynthesis levels off at a maximum and will not increase any more.

Factors Affecting PhotosynthesisFor example:Temperature: reaches a maximum rate and then decrease until there is NO more photosynthesis.•Why? Enzymes begin to become unstable and ineffective.•Stomata close and limit water loss and CO2 entry.

• Some scientists consider this process of photosynthesis the single most important chemical reaction that occurs on Earth.

• Why?

Science Fact

•Some scientists have a theory about the first cells that appeared on earth about 3.5 billion years ago.

•Early cells had to survive in a harsh environment. ..

•Why do you think photosynthesis might have helped different life forms to appear on Earth?

•In most organisms, two things are needed for cells to get energy: food and oxygen.

•The process by which cells release energy from food is called cellular respiration.

•Cellular respiration is carried out by every cell in both plants and animals and is essential for life.

CELLULAR RESPIRATION

After you eat an apple, your cells are ready to use that stored chemical energy, but

how does this happen?

The release of energy occurs in a series ofenzyme-controlled small steps:

• The energy stored in glucose is convertedinto a usable form, the energy source of all cells, adenosine triphosphate, or ATP. • Cells use the energy from to perform

many functions, such as obtaining materials and eliminating wastes.

• Cellular respiration is basically the opposite of the process of photosynthesis.

• Instead of being produced in the cells, the energy-rich glucose molecules are taken apart to release their stored energy.

• Cellular respiration can be summarized by the following chemical equation:

C6H12O6 + O2 ATP (energy) + H2O +CO2

Sugar + Oxygen ATP (energy) + Water + Carbon dioxide

ATP P P P ADP P P

P

+Energy

ATP --> ADP + P + Energy

Bond is Broken

Partiallychargedbattery

Fullychargedbattery

How do you get energy from ATP?

AEROBIC vs. ANAEROBIC RESPIRATION

In most cells, each molecule of glucose enters into a series of reactions that produce 38 ATP molecules.This process is referred to as aerobic respiration because oxygen is used to help produce the ATP molecules.

AEROBIC vs. ANAEROBIC RESPIRATION

Glycolysis: •the splitting of the glucose molecule; this process yields a small amount of energy as ATP

During anaerobic respiration, energy is released without the use of oxygen. Both Aerobic respiration and Anaerobic respiration begin with glycolysis:

Aerobic respiration continues after glycolysis, through a complex series of chemical reactions called the Krebs Cycle, & Electron Transport Chain. Both of these

reactions take place in the mitochondria of the cell.

The “Mighty” Mitochondria

Anaerobic respiration, also called FERMENTATION, continues after glycolysis, but does not take place in the mitochondria as with aerobic respiration, but in the cytsol.Fermentation occurs when there no oxygen present.

Two types of Fermentation:1.) Lactic Acid-lactic acid is by-product2.) Alcoholic- ethyl alcohol and carbon dioxide are by-products.

Lactic Acid Fermentation Used By:• Some Microorganisms - make yogurt

and cheese• Animals - happens in muscles during

exercise when need more oxygen, but can’t get it. Cause muscle soreness.– Lactic acid transported to liver where

converted to glucose.

Alcoholic Fermentation Used By:• Yeast Cells

– Alcohol in wine and beer is produced this way (carbon dioxide allowed to escape-alcohol stays).

– Bread is also made this way-carbon dioxide produced make bread rise…alcohol evaporate during baking.

800 × 600 - biochemaholic.wordpress.com

AEROBIC vs. ANAEROBIC RESPIRATION

Science Fact

An active cell requires about two million molecules of ATP per second to perform its life functions.

Science Fact

A steady supply of ATP is so critical for life that a poison which attacks any of the proteins used in ATP production kills the organism in minutes. Certain cyanide compounds, for example, are poisonous because they bind to certain atoms which block the system in the mitochondria where ATP manufacturing occurs.

BREATHING vs. Cellular Respiration

Animals move O2 and CO2 into and out of their

bodies by mean of a respiratory system.

The process of breathing, also known as respiration, is controlled by the muscles of the ribs and the diaphragm.

RespirationIn multicellular animals, it is necessary to have breathing or respiration that involves a respiratory system in order to allow the life-sustaining activities of cellular respiration.

• All mammals, including humans, move air into their lungs by lowering the air pressure within them.

• Two sets of structures are involved: the ribs and the muscles between them.

Inhalation ~ FYI ~ Exhalation

When the muscles move the ribs upward and outward, the rib cage expands. At the same time, the diaphragm, a large flat muscle that lies across the bottom of the chest cavity, contracts and moves down. This movement increases the size of the chest cavity and decreases the air pressure in the lungs, so they fill with air.

To move air out, the diaphragm and the muscles between the ribs relax. This movement decreases the size of the chest cavity and increases the air pressure in the lungs, so air moves out.

FYI ~ Gas Exchange Surfaces

• Respiration in all organisms involves the diffusion of gases across cell membranes.• This occurs for plants in the spongy layer of cells within the plants' leaves.• Although gas exchange in animals may involve a complex respiratory system, the actual process of taking in and releasing gases is identical to that of a single-celled organism, such as the ameba.• In other words, gases must cross a barrier to be moved into or out of the animal.

FYI ~ Respiratory Surface

This barrier, a part of the animal's body, is known as the respiratory surface.

• The respiratory surface must remain moist at all times so that gases can diffuse across the cell membranes.• The respiratory surface must be very thin so that gases are able to pass through it.• There must be a source of oxygen, either in the air or dissolved in the water.• The respiratory surface must be closely connected to the transport system that delivers gases to and from cells.

The lining of the alveoli acts as our respiratory surface-it is where gas

exchange occurs in our bodies.

PHOTOSYNTHESIS

CELLULAR RESPIRATION