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Energy in a Cell

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									Energy in a Cell Photosynthesis & Cellular Respiration

Overview of Photosynthesis and Respiration
SUN

RADIANT ENERGY
PHOTOSYNTHESIS
RESPIRATION

CELL ACTIVITIES

GLUCOSE

ATP (ENERGY)

The Need for Energy

In other words… who cares!?

Cell Energy
• Energy is essential for life
– Active transport, cell division, flagella movement, protein production

• Some capture energy from light or chemicals
– Autotrophs

• Others eat those that capture energy
– heterotrophs

So Where Is Energy Found?
Energy is stored in chemical bonds of ATP
– Adenosine Triphosphate (ATP)
• Adenosine molecule with three phosphate groups • Energy carrier molecule of the cell

Question…?
How do you release the energy stored in the bonds?

Answer
Break the bond!

Energy is Stored in the BOND!

Forming and Breaking Down ATP
• Adenosine monophosphate (AMP) • Adenosine diphosphate (ADP) • Adenosine triphosphate (ATP) • ATP  ADP + P + Energy • Energy + P + ADP  ATP

How Cells Tap Into the Energy Stored in ATP
•Many proteins have sites for ATP binding •When the phosphate bond is broken, energy is released and used to carry out cell processes Analogy: ATP = Battery Device = Protein

Where Does The Energy Come From!?

Trapping the Sun’s Energy

Photosynthesis:

What is Photosynthesis?
The process of photosynthesis is a chemical reaction.
It is the most important chemical reaction on our planet. Tell me… WHY?

What is the Equation for the Chemical Reaction of Photosynthesis in WORDS?

What is the Equation for the Chemical Reaction of Photosynthesis (SYMBOLS)?

Remember: Six molecules of carbon dioxide react with six molecules of water to form 1 molecule of glucose and six molecules of oxygen.

EQUATION FOR PHOTOSYNTHESIS

WATER

OXYGEN

6CO2 + 6H2O +ENERGY
CARBON DIOXIDE

C6H12O6 + 6O2
GLUCOSE

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 Happens During Photosynthesis – An Overview
• Plants capture light energy and use that energy to make glucose • Sunlight provides the energy needed by chlorophyll to change molecules of carbon dioxide and water into glucose
• Oxygen is also released in this reaction

What Happens During Photosynthesis – More Specific?
• Carbon dioxide enters the leaf through holes called stomata • CO2 combines with the stored energy in the chloroplasts through a chemical reaction to make glucose • The sugar is moved through tubes in the leaf to the roots, stems and fruits of the plants • Some of the sugar is used right away by the plant for energy; some is stored as starch; and some is built into plant tissue

Why is this Important?

In other words… who cares!?

The Importance…
The Big Two Reasons: 1. We cannot make our own food (glucose, energy), we must get our food from plants. (Plants are the first step in the food chain.) 2. The oxygen released during photosynthesis is necessary for all living things.

The Details

Trapping Energy from Sunlight
• Photosynthesis
– Process that uses the sun’s energy to make simple sugars
• Glucose, Fructose, Galactose

• Light-dependent Reactions
– Convert light into chemical energy (ATP)

• Light-independent Reactions (Calvin Cycle)
– Fueled by ATP – Produce simple sugars – 6CO2 + 6H2O  C6H12O6 + 6O2

Chloroplasts and Pigments
• Pigments
– Molecules in thylakoid membranes that absorb specific wavelengths of sunlight – Cholorophyll is the most common pigment
• Absorbs most wavelengths of light except for green.

Light-Dependent Reactions
• Light energy hits thylakoid discs • Electrons are charged with energy and EXCITED! HOT! • Electron Transport Chain
– Electrons travel through a series of proteins – Lose energy which is used to make ADP into ATP

• Electrons reach a second photosystem (pigments) and are recharged • Travel down a 2nd transport chain

Light-Dependent Reactions
• Electrons, at end of chain, transferred to a carrier molecule (NADP+ ) • NADP+ + electron + H = NADPH • Carries the electron to the Stroma • NADPH used in Calvin Cycle

Restoring Electrons
• Photolysis (lysis = to break down)
– Reaction where water is split H20  O + 2H+ + 2e
– Oxygen released into air (O2) – The electrons are used by chlorophyll – Hydrogen ions are taken to thylakoid discs

• Chemiosmosis
H+ moves across membrane due to concentration gradient Creates charge / energy = used to make ATP

Light-Independent Reactions
The DARK Reactions

• Calvin Cycle
– Series of reactions that uses CO2 to create sugars

• Takes place in the Stroma • Named for Melvin Calvin

A Summary of Photosynthesis
H2 O

+
Energy
ATP and NADPH2

CO2

Which splits water

Light is Adsorbed By Chlorophyll

ADP NADP

Calvin Cycle

Chloroplast

Used Energy and is recycled.

O2 Light Reaction

+

C6H12O6 Dark Reaction

Getting Energy to Make ATP

What is Cellular Respiration?
The release of chemical energy for use by cells.
Once the energy that was in sunlight is changed into chemical energy by photosynthesis, an organism has to transform the chemical energy into a a form that can be used by the organism. This process is cellular respiration.

Describe Cellular Respiration
1. The breakdown of glucose molecules to release energy 2. Takes place in all living things 3. Is a step by step process

What is the chemical equation for cellular respiration?

EQUATION FOR RESPIRATION
CARBON DIOXIDE

GLUCOSE

ATP

C6H12O6 + 6O2
OXYGEN

6CO2 + 6H2O + ENERGY
WATER

Do You See The Relationship with Photosynthesis!?
Respiration has the SAME formula as photosynthesis except it is backwards!

Cellular Respiration
• Process by which mitochondria break down food molecules to produce ATP • Three Stages
– Glycolysis – Anaerobic – Citric Acid Cycle – Aerobic – Electron Transport Chain - Aerobic

Glycolysis
• Glucose gets broken into two three carbon pyruvic acids • 2 ATP used to start this reaction • Reaction produces 4 ATP

• Net gain = 2 ATP
• NAD+ = electron carrier = NADH when it accepts two electrons

• Pyruvic molecules move into Mitochondria • IF OXYGEN IS PRESENT then the Citric Acid cycle takes place
– Pyruvic acid looses one carbon (CO2) – Combines with Coenzyme A to create Acetyl-CoA

Citric Acid Cycle (Krebs)

Electron Transport Chain

Fermentation
• Times when there is not enough oxygen to do Citric Acid Cycle

• Net Gain = 2 ATP
• Two major types
– Lactic Acid – Alcoholic

Respiration
PROTEINS CARBO’S (SUGARS)

CYTOPLASM
GLYCOLOSIS HAPPENS HERE!

FATS (LIPIDS) AMINO ACIDS GLUCOSE C6H12O6 GLYCOLOSIS IN CYTOPLASM NO OXYGEN!

MAKES 2 ATPS

ATP TOTALS GLYCOLOSIS=2 RESPIRATION=34 BOTH=36!

PYRUVIC ACID

ACETYL-CoA

CO2 IS RELEASED

O2 ENTERS HERE MITOCHONDRIA
RESPIRATION HAPPENS IN THIS ORGANELLE!
KREBS CYCLE AND ELECTRON TANSPORT MAKES 34 ATPS

Compare and Contrast
Photosynthesis & Cellular Respiration

Photosynthesis & Cellular Respiration are Interconnected

The End


								
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