Energy and Life

Without the ability to obtain and use energy, life would

cease to exist.

Chemical Energy & ATP

Energy comes in many forms:

Light

Heat

Electricity

When a candle burns, what is happening?

ATP

The principal chemical

compound used for energy.

What is ATP?It contains the following:

Adenine

5 – Carbon Sugar (Ribose)

3 Phosphate GroupsAnalogy: ATP is like a ……

The three phosphate groups are key to storing and

releasing the energy of ATP.http://www.biologyinmotion.com/atp/index.html

What is ADP?A battery that needs charged!!!

It is just like ATP, but is missing a phosphate group.

To store energy the third phosphate group is added to make ATP.

How does ATP release its energy?

How Do Cells Use the Energy of ATP?

Active Transport – Pumps Na+ out of the cell and K+ into the cells to maintain ion balances.http://highered.mcgraw-hill.com/sites/0072495855/student_view0/chapter2/animation__how_the_sodium_potassium_pump_works.html

Motor Proteins – ATP gives these proteins the energy they need to move organelles around the cell.

Blink of a Firefly – ATP powers the enzymes that allow fireflies to blink

Protein Synthesis – Helps to bond amino acids together to make proteins..

Why Do Cells Contain Only a Small Amount of DNA?

Cells only have enough ATP to fuel the cells for a few seconds.

ATP is great at transferring energy, but not at storing it.

Glucose stores 90x more energy the ATP!!

Photosynthesis

Plants use the sun’s energy to convert CO2 &

H2O.

Van Helmont’s Experiment

1600’s

He planted a seedling in a measured amount of soil. After 5 years, he had a small tree, but

the mass of the soil was unchanged.

What did he conclude?

He only added one thing to the seedling….

Priestley’s Experiment

He put a glass jar over a candle. What happened?

Then he put a sprig of mint with the candle under the glass jar. What happened to the candle

this time?

Jan Ingenhousz Experiment

He found that Priestly’s results were only valid if sunlight was present.

The work of the three men led to what we know about photosynthesis today……it requires light, and can turn

CO2 and H2O into sugars while giving off oxygen.

Once the glucose is made, it can be converted into complex starches.

Light and Pigments of Photosynthesis

Pigment – light absorbing molecules found in autotrophs (absorb the energy with the light)

Chlorophyll – plants principal pigment (chlorophyll a & b) – reflects green wavelengths of light

Structure of a ChloroplastThylakoids – sac – like photosynthetic membranes found in chloroplasts

Grana – stacks of thylakoids

Photosystems – clusters of pigments and proteins that absorb light energy in thylakoids

Stroma – outside the thylakoid membrane where Calvin Cycle occurs

Light Dependent Reactions

Occurs only with sunlight.

Makes ATP & NADPH

Occurs in the Thylakoid Membrane

Light Independent ReactionsCalvin Cycle

Don’t need sunlight

Makes the sugars (glucose)

Occurs in the Stroma

Electron CarrieresLight “excites” electrons in chlorophyll. Theses excited elections are then carried from chlorophyll to OTHER MOLECULES.

Carrier Molecule – A compound that can accept a pair of high energy electrons and transfer the electron and their energy to another molecule.

Ex. NADP+ - A carrier Molecule

It becomes NADPH when it accepts electrons and their energy.

This energy is then used to build energy rich molecules.

THE LIGHT DEPENDENT REACTIONS

FIRST STEP

Photosystem II Pigments absorb sunlight. That

energy is absorbed by two electrons and passed to

the ELECTRON TRANSPORT CHAIN. (the carriers)

SECOND STEP

These excited electrons are moved to

Photosystem I (with their energy). The energy is used to

transport H+ ions from the stroma to the thylakoid space.

THIRD STEPIn Photosystem I, its

pigments absorb more light and reenergize the

electrons.

NADP+ picks up the electrons and H+ ions on

the surface of the thylakoid membrane and becomes

NADPH.

FOURTH STEPAs the electrons are

passed from chlorophyll to NADP+, H+ ions are

pumped across the membrane. This makes

inside the thylakoid + and the outside -. This charge

difference produces energy to make ATP.

FIFTH STEP

ATP Synthase in thylakoid membrane to allow H+ to pass

and adds a phosphate to ADP to

make ATP.

The Calvin Cycle

ATP and NADPH will only remain stable for

a few minutes. The Calvin Cycle uses the ATP and NADPH from the light-dependent reactions to produce high-energy sugars.

Step 1

3 CO2 molecules enter the cycle from the air and combine with 3, 5

carbon molecules (RuBP) .

The result is 6,3 carbon molecules

(PGA).

Step 2

The 6, 3-carbon PGA molecules are

converted then to higher energy forms

by adding a phosphate group.

(energy comes from 6 ATPs and high energy electrons

form NADPH)

1 of the 6, 3 carbon molecules (G3P) are

removed to make sugar, lipids, and

other compounds. Another 3 carbon G3P molecule is

need to make sugar. Hence, a repeat of

the cycle.

Step 3

Step 4The 5 remaining 3 carbon molecules are converted into

5, 5 carbon molecules to be

reused in step 1. ADP and NADP+

will be reenergized in light reactions.

http://www.stolaf.edu/people/giannini/flashanimat/metabolism/photosynthesis.swf

What Affect the Rate of

Photosynthesis?