Topic 5: Cellular Energy After studying this topic you should be able to –Describe the importance of energy in the cell –Describe the First Law of Thermodynamics.

Topic 5: Cellular EnergyTopic 5: Cellular Energy• After studying this topic you should be able to

– Describe the importance of energy in the cell– Describe the First Law of Thermodynamics– Describe the Second Law of Thermodynamics– Explain how energy is stored in the bonds of ATP– Outline the uses of ATP in the cell

• Energy is the ability to do work• Where do organisms obtain

their energy?– FOOD!!!

Importance of Cellular EnergyImportance of Cellular Energy

Organisms Obtain Food in Two WaysOrganisms Obtain Food in Two Ways• Autotrophs

– Use sunlight directly to make their own food

– Examples: plants (trees, flowers, grass), photosynthetic algae

• Heterotrophs– Consume food, such as

plants and animals – Examples: animals (birds, reptiles,

fish, mammals, insects) In both autotrophs and heterotrophs,

energy transfers are occurring!

Energy Relationships: ThermodynamicsEnergy Relationships: Thermodynamics• The study of energy relationships is called thermodynamicsFirst Law of Thermodynamics

– Energy cannot be created or destroyed, but can be changed from one form into another

• Energy trapped by plants during photosynthesis is not destroyed when plants are eaten by a heterotroph...it just changes form

• Energy passes from organism to organism • At each passing of energy some energy is lost as heat

Energy Relationships: ThermodynamicsEnergy Relationships: Thermodynamics• Second Law of Thermodynamics

– All conversions of energy produce heat, which is waste energy and is not useful for life processes

• When a muscle cell uses chemical bond energy to contract, not all the energy is used for movement

• Some energy is given off as heat, which results in an increase in body temperature during exercise

• Heat is considered to be waste energy in the body, because it cannot perform any work in the cell

ATP: Adenosine TriphosphateATP: Adenosine Triphosphate• Burning glucose (sugar) with oxygen

outside a living system produces a large amount of energy!

• The amount of energy produced would destroy a cell if released all at once!

• Cells actually store most of the energy produced by the combustion of glucose in a molecule called ATP

(Adenosine TriPhosphate)

Gummy bear combustion

ATP ATP

Adenine

Ribose3 phosphate groups

Special High Energy Bond

From ADP to ATP? During cellular reactions (i.e. When we eat) a THIRD phosphate

group is added to ADP… creating ATP!

ATP then stores this energy until it is required by the cell for life processes (like muscle contractions)

ADPPhosphate

ATP

2. How is ATP broken down to release energy?

ATP ADP + P + energy

From ADP to ATP?

High energy bond is BROKEN to RELEASE energy!

From ADP to ATP?

3. What happens when energy is stored?

ADP + P ATP

High energy bond is FORMED to STORE energy!

Energy Release Cycle in the CellEnergy Release Cycle in the Cell

ATP

ADP

Energy and phosphate released

Energy and phosphate

stored

ATP – P ADP

ADP + P ATP

Photosynthesis: Introduction• Most organisms obtain their energy

indirectly or directly from the sun• Through photosynthesis, autotrophs

(plants) capture light energy from the sun

• The captured energy is stored in chemical bonds of many different molecules like sugars (glucose)

• Consumers eat autotrophs (or other animals that have eaten plants) to obtain energy from chemical bonds

Topic 6: Photosynthesis

photo synthesis

“light” “to make or build”

Purpose: to turn energy from the sun into energy that can be used by the plant (chemical)

Result: creation of glucose and O2 gas

Photosynthesis EquationPhotosynthesis Equation

6H2O C6H12O6 +water glucose oxygen

6CO2 +Carbon dioxide

6O2

sunlight

Chlorophyll (in

chloroplasts)

Reactants Products

PhotosynthesisPhotosynthesis

Oxygen

http://www.wonderville.ca/asset/photosynthesis Interactive video on

photosynthesis. Good for self practice

thylakoids =

“pancake” shaped structures inside a chloroplast. Site of light reactionsStroma = fluid surrounding thylakoids. location of chemical reactions that produce glucose. Site of light independent reactions

• In almost all producers, photosynthesis occurs inside cellular organelles called chloroplasts

Photosynthesis Song

Click here to listen to the Photosynthesis

Song!

• Pigments in the chloroplasts capture radiant energy from the sun. The most important pigment is the green pigment chlorophyll. Chlorophyll absorbs red and blue wavelengths and reflects green light.

Why are Plants Green?

Photosynthesis: Two Reactions• Light Reactions:

– radiant energy is trapped and converted to ATP and to another energy storage molecule known as NADPH

– Water (H2O) is split into hydrogen and oxygen– This is where the oxygen gas (which is a by-product of

photosynthesis) is produced

Light-DependentReactions

Light Energy

O2

ATP

NADPHWater

Thylakoid

• Light-Independent Reactions (Dark Reactions)– Given name not because they occur in the dark!!– Light is not necessary for them to occur– Energy stored in ATP and NADPH during light reactions

combine with carbon dioxide to produce glucose

Light-DependentReactions

O2

ATP

NADPH

Photosynthesis: Two Reactions

Light-IndependentReactions (dark)

Sugar(glucose)(C6H12O6)

Light Energy

Water

Thylakoid Stroma

Calvin-BensonCycle

– Water splits into oxygen and hydrogen.

– The oxygen is given off as a gas.

– Hydrogen enters the thylakoid and is added to NADP+ to form NADPH, a high energy molecule

Light Dependent Reactions

Light-DependentReactions

Light Energy

O2

WaterNADPH

H+

NADP+

=NADPH

Thylakoid

Chemiosmosis is the name for the process in which ATP is created when hydrogen atoms move out of the thylakoid membrane through an enzyme called ATP synthase

Light Dependent Reactions

Light-DependentReactions

Light Energy

O2

WaterNADPH

ATP

H+

ATP synthas

e

H+ADP +

Pi

ATP

Thylakoid

Chemiosmosis

In the Calvin-Benson cycle, the carbon atom in carbon dioxide is used to make glucose.

Light Independent Reactions in the Stroma

CO2 C6H12O6

PhotosynthesisEnergy Reactions Location

Light energy captured from the Sun

Water splits, forms oxygen

Large amounts of ATP produced  

Chemiosmosis  

Energy from the light-dependent reactions is used to make glucose   

Calvin-Benson cycle

thylakoid membrane

thylakoid membrane and stroma

stroma

http://highered.mheducation.com/sites/0073532223/student_view0/chapter8/3d_animation_-

_photosynthesis.html

Photosynthesis video 7:24

Explain the results of the graphs.

Explain the results of the graphs.

Photosynthesis Lab (Bozeman) 6:44 https://www.youtube.com/watch?v=ZnY9_wMZZWI

Products

Reactants

1. Sunlight energy 2. Carbon

dioxide 3. Water

4. glucose

5. Oxygen

6. chloroplast

Photosynthesis Song (Let’s get into this rap)

Click here to listen to the photosynthesis rap!

http://www.youtube.com/watch?v=pE82qtKSSH4

Topic 7: Cellular RespirationTopic 7: Cellular RespirationNecessary for the life of EVERY cell (both plants and animals)Cellular respiration provides energy in the form of _____ for

processes in the cell such as:• Active transport – the movement of molecules across the cell

membrane against the concentration gradient• Phagocytosis – cell intake of large food particles• Muscle contraction – energy is required to move muscles

Aerobic RespirationAerobic Respiration

Reactants Products

CHEMICAL EQUATION:

C6H12O6 + 6O2 6CO2 + 6H2O + ATP

Aerobic•Uses oxygen•Produces 36 ATP

Anaerobic•Does not use oxygen•Produces only 2 ATP

CellularCellular RespirationRespiration

Two Types of Cellular Respiration

https://www.youtube.com/watch?v=00jbG_cfGuQ

Anaerobic

respiration in

cytoplasm

Crash course in cellular respiration 13:25

Aerobic Cell Respiration: Part 1• Two major steps in aerobic respiration

– #1. Glycolysis (occurs in cytoplasm)• Series of chemical reactions that break the glucose

molecule into two small pyruvic acid molecules• Only two molecule of ATP are produced in glycolysis

Glucose 2 pyruvates

Cell Respiration: Step 1 – Glycolysis (Occurs in the cytoplasm)

2 ATP

#2. Krebs Cycle (occurs in mitochondria)• Pyruvic Acid moves into the mitochondrion where it is

used to make to release a large amount of ATP, carbon dioxide, water and waste heat energy

ElectronTransport System

Kreb’s

Cycle

CO2

NADH

FADH2

2 ATP 32 ATP

H+ ions move through ATP synthase creating ATP through the process of chemiosmosis. (Just like photosynthesis)

H2O

O2

Products

Reactant

Reactants

36 ATP

A.Glycolysis 1. Glucose

2. Pyruvic acid3. oxygen

5. water

4. Carbon dioxide

6. Energy (ATP)

7. Mitochondrion

B. Krebs cycle

Alcohol Fermentation• occurs in yeast cells

Muscle Fermentation• Occurs in muscle cells

AnaerobicAnaerobic RespirationRespiration

Two types of anaerobic respiration (fermentation)

• Cell respiration WHEN OXYGEN IS NOT PRESENT! • Only two ATP produced due to the incomplete breakdown of

glucose• Occurs in the cytoplasm of yeast cells and muscle cells

• Have you ever eaten bread? Ever drank an alcoholic beverage? Enjoyed a warm mug of apple cider? Well, then you’ve experienced alcohol/ethanol fermentation!

Alcohol Fermentation(yeast cells):

Glucose 2 pyruvic acidsEthyl Alcohol

and CO2

2 ATP

Remember: This happens when there is

no oxygen

Have you ever worked out for a long period of time and were out of breath? How did your muscles feel after? If they were sore and cramped, then you’ve experienced the effects of lactic acid build up!

Muscle Fermentation (muscle cells):

Glucose 2 pyruvic acids Lactic Acid (aka Lactate)

2 ATP

Remember: This happens when there is

no oxygen

Anaerobic Cell Respiration AnswersAnaerobic Cell Respiration AnswersFill in the following chart:

Type of Respiration

Reactants Products Amount of ATP Produced

Aerobic

AnaerobicAlcohol Fermentation

Anaerobic Muscle Fermentation

Pyruvic acid

Carbon dioxide 34

Glucose Ethyl alcohol

2

Glucose Lactic Acid 2

CO2

Oxygen Water

Cellular Respiration Song (by the Black Eyed Peas? :)

Click here to listen to the cellular respiration

song (first half of the song)!

Comparison of Photosynthesis and Comparison of Photosynthesis and RespirationRespiration

Cellular RespirationPhotosynthesis

Reactants: Reactants: 6CO6CO2 2 + 6H+ 6H22OO

Products: Products: CC66HH1212OO66 + 6O + 6O22

- Energy is Energy is REQUIREDREQUIRED

Overall Chemical Reaction:Overall Chemical Reaction:6CO6CO2 2 + 6H+ 6H22O O C C66HH1212OO66 + 6O + 6O22

Reactants: Reactants: CC66HH1212OO66 + 6O + 6O22

Products: Products: 6CO6CO2 2 + 6H+ 6H22OO

- Energy is Energy is PRODUCEDPRODUCED

Overall Chemical Reaction:Overall Chemical Reaction:CC66HH1212OO66 + 6O + 6O2 2 6CO 6CO2 2 + 6H+ 6H22O O

Notice that photosynthesis and cellular respiration are opposite

reactions!

Comparing photosynthesis & cell respirationComparing photosynthesis & cell respirationStatement Photosynthesis Respiration

Occurs in green plants, algae and blue green algae

Occurs in both plants and animals

Uses carbon dioxide

Produces carbon dioxide

Uses glucose

Produces glucose

Uses water

Produces water Requires sunlight

Requires chlorophyll

Happens in the mitochondrion

Happens in the choloroplasts

Relationship between Photosynthesis Relationship between Photosynthesis and Respirationand Respiration

Photosynthesis (in chloroplasts)

Cellular Respiration (in mitochondria)

C6H12O6

O2

CO2

H2O

ATP