The Flow of Energy

• Cellular Respiration– is the set of the metabolic reactions and

processes that take place in organisms' cells to convert biochemical energy from nutrients into adenosine triphosphate (ATP

Laws of Thermodynamics

• There are 2 Laws of Thermodynamics• Law #1 Conservation of energy

– Energy can be converted from one form to another

– energy cannot be created or destroyed

• Law #2 Entropy increases• Energy can not be converted without the

loss of usable energy – (usually Thermal or Heat)

Autotrophs & Heterotrophs

• Autotrophs• organisms that make

their own food. – Plants

• Heterotrophs • need to ingest food to

obtain energy– Animals

Endergonic And Exergonic reactions

• Endergonic reactions REQUIRES free energy

• Exergonic reactions RELEASE free energy

• The cell requires these reactions to be linked together in order to carry out biological processes

Definitions

• Aerobic Respiration – Respiration in which Oxygen is required

• Anaerobic Respiration– Respiration in which Oxygen is not required

Respiration with Oxygen

Aerobic Respiration

•Is the normal form of respiration. It requires oxygen and releases the most energy from glucose.

This type of energy reaction requires us to

• breathe oxygen in , breathe carbon dioxide out, excrete (get rid of) the extra water in our urine.

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Anaerobic Respiration

• No Oxygen Is used• Lactic Acid is formed• anaerobic respiration

is used for short periods of time

• Ex. during a sprint, human muscles can respire anaerobically.

Anaerobic Respiration

• Unfortunately, lactic acid is produced and accumulates until the muscles cannot continue working. Anaerobic respiration in humans is less efficient than aerobic respiration at releasing energy, but releases energy faster This explains why humans can run faster in a sprint than over longer distances. When humans stop after a sprint, they have to continue breathing more heavily for a while. This is to take in ‘extra’ oxygen in order to break down the accumulated lactic acid on top of the ‘normal’ breakdown of sugar in aerobic respiration. The body is paying back the oxygen debt built up during the sprint.

ATP- The Unit of Cellular energy

• Adenosine Triphosphate

• Structure is A-P-P-P• When the bond

between the last 2 phosphate groups is broken energy is released

• A-P-P P• ATP movie

ATP

• ATP consists of a base, in this case adenine (red), a ribose (magenta) and a phosphate chain (blue).

ATP

• How it works• ATP releases energy when the

bond between the second and third phosphate is broken

• This forms – ADP (adenosine diphosphate )– A free Phosphate group

• Note – this is hydrolysis reaction – Therefore water is involved

ADP

• When the organism is rest, the reverse reaction takes place

• the phosphate group is reattached to the molecule using energy obtained from food or sunlight.

• ATP molecule acts as a chemical 'battery', storing energy when it is not needed, but able to release it instantly when the organism requires it.

ATP

• In other words:

ATP+H2O ADP+P(i) +energy

Electron Transport System

• Makes most of the ATP for the cell

• Electrons move from high energy levels to lower energy levels

• The Energy released as electrons move to lower level is used to ATP

Oxidation-Reduction Reactions (Re-dox) Rxns

• The transferring of electrons between energy levels

• Oxidation reactions– Process of losing electrons

• Reduction Reactions– Process of gaining electrons

Called a reduction reactions because you are reducing the charge by gaining more electrons

Electron and Protein Carriers

1. NAD+ (Nicotinamide adenine dinucleotide)

– Is an electron proton carrier in cellular respiration

– In cellular respiration NADH is formed from NAD+ gaining a hydrogen with its proton and electron. NADH can convert back to NAD+ by giving off its hydrogen with its proton and electron

2. NADH+ (Nicotinamide adenine dinucleotide phosphate)

– Is an electron and proton carrier in photosynthesis

– In photsynthesis NADPH is formed from NADP+ gaining a hydrogen with its proton and electron. NADPH can convert back to NADP+ by giving off its hydrogen with its proton and electron

Three Main Stages of Cellular Respirations

1. Glycolysis

2. Citric Acid Cycle or Kreb's Cycle

3. Electron Transport

Video

Photosynthesis

Photosynthesis Photosynthesis

• Plants absorb a common gas called carbon dioxide, pull water up through their roots and use light to make sugar. Plants use the sugar to grow. Plants give off oxygen as a by-product. The green parts of the plant makes the sugar and oxygen. 

• Carbon dioxide + water + sunlight = sugar + oxygen

• Plants absorb a common gas called carbon dioxide, pull water up through their roots and use light to make sugar. Plants use the sugar to grow. Plants give off oxygen as a by-product. The green parts of the plant makes the sugar and oxygen. 

• Carbon dioxide + water + sunlight = sugar + oxygen

Photosynthesis

• A process in which light energy is converted into chemical energy

• The chemical equation for photosynthesis is

6CO2+6H20 -> C6H12O6+602 light

Photosynthesis occurs in two phases

• Phase 1– Light dependent reactions– Light absorbed and convert into chemical

energy in the form of ATP or NADPH

• Phase 2 – Light Independent reactions– ATP and NADPH are used to make glucose– Glucose combine with other sugars to form

complex Carbohydrates such as Starch

Photosynthesis is a two stage process

• . The first process is the Light Dependent Process (Light Reactions), requires the direct energy of light to make energy carrier molecules that are used in the second process. The Light Independent Process (or Dark Reactions) occurs when the products of the Light Reaction are used to form C-C covalent bonds of carbohydrates

The Light Reactions

1. Light Reactions • The purpose of the light reactions is to change

light energy into chemical energy of ATP and NADPH (enzyme).

• Light energy is absorbed and converted to chemical energy

• Water is split into H+ ions, oxygen and electrons• H+ from the water are attached to carrier co-

enzymes (NADP) for use in photosynthesis (see page 157)

1. Light Reactions • The purpose of the light reactions is to change

light energy into chemical energy of ATP and NADPH (enzyme).

• Light energy is absorbed and converted to chemical energy

• Water is split into H+ ions, oxygen and electrons• H+ from the water are attached to carrier co-

enzymes (NADP) for use in photosynthesis (see page 157)

The Calvin Cycle AKA

The Dark Reactions• The purpose of the Calvin Cycle is to

change CO2 into sugar by adding energy & the H+ from ATP & NADPH.

• a) Can occur in light or dark.• b) 6 CO2 & lots of ATP & NADPH are

needed to make one sugar molecule. • c) The sugar is then used for plant

growth or stored for use in the winter

• The purpose of the Calvin Cycle is to change CO2 into sugar by adding energy & the H+ from ATP & NADPH.

• a) Can occur in light or dark.• b) 6 CO2 & lots of ATP & NADPH are

needed to make one sugar molecule. • c) The sugar is then used for plant

growth or stored for use in the winter

Energy Relationships

• Respiration is almost the exact opposite reaction to photosynthesis. These two reactions work together to maintain a biological balance on earth.

Photosynthesis and Respiration.

• Photosynthesis• produces food • stores energy • uses water • uses carbon dioxide • releases oxygen • occurs in sunlight

• Respiration• uses food • releases energy • produces water • produces carbon

dioxide • uses oxygen • occurs in the dark as

well as light

Photosynthesis and Respiration. • Photosynthesis•  light energy

• 6CO2+6H20= C6H12O6+6O2  

• Here is the equation for photosynthesis.  when a plant is exposed to 6 molecules of carbon dioxide and 6 molecules of water and light energy is present, glucose and oxygen gas is formed. 

• Cellular Respiration 

•        C6H12O6+6O2=CO2+H2O

• this equation is about the opposite of the equation for photosynthesis. 

• products of the photosynthesis reactions are the reactants of the reactions that take place during cellular respiration. 

• Conversely, the products of cellular respiration are the reactants of the photosynthesis reactions.