Cellular Energy

Chapter 8

8.1 How Organisms Obtain Energy

All living organisms use energy to carry out all biological processes.

Energy• Nearly all the energy on this planet comes from

the sun• Winds (hurricanes and tornadoes) are powered by

the sun.• Rivers (and waterfalls) are powered by the sun

(getting the water to higher ground as rain).• Plants (and indirectly animals) are powered by

the sun.• Fossil fuels (coal, oil & natural gas) are remains of

dead plants and animals

How do we get energy?

• EATING!o OUR BODIES BREAK DOWN

THE FOOD WE EAT SO WE CAN GET ENERGY

Transformation of Energy

• Energy: The ability to do work

• In our cells, energy is stored in the form of ATP…

ATP• ATP = Adenosine Triphosphate• 1 large molecule that is made of 5 smaller

molecules bonded together

• Adenine, ribose, and 3 phosphate groups

ATP• ATP breaks

apart and releases its energy to cells

ENERGY!!!

ATP• When is

breaks apart, it releases energy and loses a phosphate group, now it is called ADP

Then what?• ATP breaks apart and creates energy and ADP…

then what happens?

• It is recharged! It uses energy and gains and extra P is becomes ATP again

ADP ATP

ADP ATP

Adenosine diphosphate (ADP) + Phosphate Adenosine triphosphate (ATP)

Energy

Energy

Partiallychargedbattery

Fullychargedbattery

How do the things we eat get energy?

Autotrophs & Heterotrophs

• Autotrophs – organisms that make their own energy for food

• Heterotrophs – organisms that need to ingest food to obtain energy

Energy• Plants use energy from the sun to grow and make

their own energy

• HOW DO THEY DO THIS?

8.2 PhotosynthesisLight energy is trapped and converted into chemical

energy during photosynthesis

Photosynthesis • “Photo”– light• “Synthesis” – putting together• Process of plants making their own food by

combining carbon dioxide and water to form sugar and oxygen in the chloroplasts

• Requires energy form the sun to happen• The process is cyclical, the products from one

reaction are the reactants for the next reaction

• The food produced is glucose (a simple sugar) and oxygen (which we like!)

carbon + water glucose + oxygendioxide

Which part of the plant do you think

photosynthesis happens in?

Chloroplast• Chloroplasts!

• Inside each chloroplast is where the photosynthesis reaction takes place.

Chlorophyll• Chlorophyll - the main

pigment found in the chloroplasts responsible for photosynthesis, they have the ability to absorb energy from sunlight

• A pigment is a colored chemical (like a dye), chlorophyll gives most leaves their green color

• Different chlorophylls absorb different wavelengths of light

Photosynthesis• There are two parts, light independent, and light

dependent

• Light dependent takes place in the light

• Light independent takes place in the dark

Phase 1: Light Reactions

• The “photo” part• The light is captured by chloroplasts and turned

into chemical energy (ATP)

Phase 2: The Calvin Cycle

• In the second phase, called the Calvin cycle, carbon dioxide is used to make sugar (glucose)

• The “synthesis” part

• Light independent

CALVIN CYCLE

CARBON DIOXIDE

ATP

GLUCOSE

ATPLight Reactions

Calvin Cycle

Light

H2O

O2

CO2

Sugar (Glucose)

Chloroplast

8.2 Cellular RespirationLiving organisms obtain energy by breaking down organic

molecules during cellular respiration.

So…• How do our bodies take food and make it into

energy?

Cellular Respiration!• Cellular respiration: is a chemical process in which

glucose molecules are broken down to release energy (ATP) for cellular functions

• Occurs in all living cells

• Cellular respiration is the opposite of photosynthesis

• Completed in the mitochondria

• The products of photosynthesis – oxygen & glucose – are the reactants needed for cellular respiration, and the products of cellular respiration – carbon dioxide & water – are the reactants for photosynthesis

What happens to the food we eat?

1. We break our food down into small molecules

2. We use the energy stored in the bonds in our food to make ATP

3. A small amount of the food becomes waste

Like photosynthesis, cellular respiration has a specific chemical reaction that

happens every time.

We breathe in oxygen and get glucose from our food

We breathe out carbon dioxide

+

C6H12O6 + 6O2 6H2O + 6 CO2 + Energy glucose oxygen water carbon dioxide (ATP)

Cellular Respiration• This process is the reverse of photosynthesis.

Cellular RespirationAnaerobic Aerobic

• Does NOT need oxygen

• Happens in cytoplasm of cell

• Fermentation

• Requires oxygen• Happens in

mitochondria• Cellular Respiration

FermentationLactic Acid Alcohol

• This is done by your muscles when the demand for ATP is high, but you are low in oxygen. (while working out) This can cause soreness in the muscles

• sugar breaks down into carbon dioxide and ethanol

• The carbon dioxide produced in this manner can be used to allow bread to rise