Cell Energetics

All Cells need energy. (Ability to perform work)

–Mitosis.

–Repair.

–Active transport.

–Movement.

What do cells use energy for?

What Is ATP?

•ATP – adenosine triphosphate is a chemical molecule made up of an adenine + ribose (adenosine), and 3 phosphate groups. It is like a battery!

Adenine

Ribose

How Does ATP Work?

• Energy is stored in the bond between the phosphate groups.

•When the end phosphates break off, energy is released!

• (ATP-ADP-AMP)

Adenine

Ribose

ATP = Energy Currency

•Within the cell, formation of ATP from ADP and phosphate (ADP +PATP) occurs over and over, storing energy each time.

•As the cell uses energy, ATP breaks down repeatedly to release energy and form ADP and phosphate.

•We refer to ATP as the battery or $ of the cell as it can be used and recharged or re-earned again and again!

Think about this… •Write the chemical formula for when the energy molecule of the cell is like a fully charged battery.

•Besides batteries and $ what is something else you can compare ATP to?

Complex Cells make energy in two specialized organelles:

–Photosynthesis – takes place in the chloroplasts

–Cellular Respiration – takes place in the mitochondria

–What about simple cells?

PhotosynthesisAutotrophs make their own food by trapping light energy (solar) to

make chemical energy (ATP) and then using that to build food energy (carbohydrates).

PhotosynthesisUsing light from the sun, plants make ATP that will in turn fuel the cells ability to combine water and carbon dioxide to ultimately make sugar .

General Equation:

6CO2 + 6H2O + ------> C6H12O6 + 6O2

Reactants Products

Enzymes & pigments

Photosynthesis

Has 2 stages/phases

The light dependent reactions

The Calvin Cycle (also called light independent reactions)

Light Dependent Reactions Light energy (solar) is used to split hydrogen from water.

– Takes place in each thylakoid in the grana (plural for granum) of the chloroplasts.

– Products are oxygen, NADPH, and ATP.–H2O + NADP +ADP NADPH + O2 + ATP

– The process of splitting water is

called photolysis.

– A) What is NADP and NADPH?

– B) What are the correct catalysts?

Think About this….

•Based on what water is broken into, what do you think the job of NADPH might be?

•What is it holding?

•Hint:

Chlorophyll is a green pigment

• Pigment = reflects some colors of light and absorbs others

• A) What color of light is chlorophyll reflecting?

• B) What colors is it absorbing?

• C) What color of light would be least useful to a plant?

• D) Why is your shirt color the color it is?

Overview!

NADP vs. NADPH

• A) What is the difference between these two items?

•B )Specifically why does H need a “taxi”? •C) What would happen if we had no “H” “taxi”?

Using Diagrams•We use diagrams to explain complex processes.

Calvin Cycle – Light Independent reactions

ATP and NADPH from the light reactions are used along with CO2 to form a monosaccharide. (like glucose)

– Takes place in the stroma of the chloroplasts.

– Products are C6H12O6 (glucose), ADP, and NADP

–General equation is:

NADPH + CO2+ ATP C6H12O6 + NADP+ADP

– ATP used to build, NADPH used as part of the sugar (H12)

–Gas exchange-stomata

Sunlight

NADP+

ADP NADPH

CO2

H2O

O2

CHLOROPLAST

ATP

Summarize• 1) What is photosynthesis?

• 2) What are the 2 main stages/phases of photosynthesis?

• 3) Explain what the goal of each stage/process is.

• 4) Why do light reactions occur first?

• 5) Where do each of the stages/processes occur?

• 6) What is an autotroph? Give an example.

• 7) What is the chemical formula for the main product made in photosynthesis?

• 8) List all the catalysts of photosynthesis indicate which stage they are used.

• 9) Where do the Carbons, Hydrogens and Oxygen specifically come from to make sugar?

• 10) Write the following equations; overall for photosynthesis, light dependent and light independent.

STOP HERE!!!

• Please wait for instructions before proceeding!

Cellular RespirationTwo ways heterotrophs can make energy:

1. Aerobic – requires oxygen, produces lots of ATP and is more efficient.

2. Anaerobic – requires an absence of oxygen, not much ATP, not efficient.

Aerobic Respiration has three separate reactions:

1) Glycolysis

2) Citric Acid Cycle

3) Electron Transport Chain

General equation is:

C6H12O6 + 6O2 --> 6CO2 + 6H2O

What is missing from this equation?

GOALS of each reaction

• Glycolysis- break sugar, recharge some used ATP batteries

• Citric Acid Cycle- Collect Hydrogen, get rid of waste products

• ETC- use Hydrogen to make ATP

Glycolysis– break a 6 Carbon glucose into 2, 3 Carbon pyruvates.

– Takes place in the cytoplasm of the cell.

– Anaerobic

– Glucose won’t break by itself, must spend some ATP to get it to break.

– C6H12O6 + 2 ATP + NAD2 pyruvates + NADH + 4 ATP

– Notice NAD…..

C6H12O6

C3H4O3

C3H4O3What’s missing????

Think - Pair - Share

•Based on what happens in glycolysis, what do you think the job of NADH might be?

•What is it holding?

Citric Acid Cycle / Kreb’s Cycleeach pyruvate is broken down further

Takes place right outside of the cristae (the folded membrane in the mitochondrion).

–O2 + pyruvate + NAD CO2 + NADH

–CO2 is released, and NAD captures

hydrogen ions (to be used later)

Electron Transport Chain

• hydrogen ions are moved using NAD to the cristae. (NADH)

• H’s leave the carrier NAD and move across the cristae and in so doing, generate a ton of energy!

• That energy is harvested to build even more ATP!

• Oxygen picks up H after they move through ATP Synthase.

• The cristae is not permeable to the carrier. (NAD)

• Water is formed as the H’s and oxygen combines.

• ADP + O2 + NADH + ATP + H20+ NAD

• We just used hydrogen power to anabolically build lots ATP! (about 30 more)

• Once we are done with ETC the cell performs chemiosmosis to move the water and the ATP out of the mitochondria for use.

Don’t talk about ATP synthase – next slide is t-p-s

Based only on the name what do you think ATP synthase does?

•The enzyme in ETC responsible for building the ATP is called ATP synthase.

Summarize

•Explain to your partner what happens in the electron transport chain.

•Partner: repeat back what they said.

•Discuss if everything stated is accurate.

MITOCHONDRION

CO2

H2O

O2 ATP

NADH

Heat

ElectronTransportSystem

ATP

NAD+

Pyruvate

GlucoseATP

Turn to your partner and explain the diagram you just filled in.

Sunlight

Photo-SystemI

Photo-systemII

NADP+

ADPNADPHATP

CalvinCO2

H2O

O2

ATP

ATP

NAD+ NADH

ElectronTransportSystem

Cycle

CitricAcid

Heat

CHLOROPLAST MITOCHONDRIONATP

Glycolysis

Glucose Pyruvate

Cycle

Anaerobic Respiration

Certain cells in our body can produce energy without oxygen, mainly our muscle cells.

Anaerobic respiration is the process that recycles NAD the absence of oxygen. Through

fermentation, anaerobic organisms and cells can exist w/o oxygen by using the small amount of

energy supplied by glycolysis.

Fermentation

Allows glycolysisto continue in the

absence of oxygen.

Recycles NAD+

Does not produce any ATP

Two types of Fermentation:• Alcoholic fermentation (alcohol and CO2 are

waste products) – occurs in yeast and fungi

• Lactic acid fermentation (lactic acid is a waste product) – occurs in animals