Download ppt - Energy represents the capacity to do work. Cells must acquire energy from their environment. In life, energy transformations consist primarily of movement

Energy represents the capacity to do work.Cells must acquire energy from their environment.

In life, energy transformations consist primarily of movement of molecules and changes in chemical bonds.

Metabolismis the set of chemical reactions that

happen in living organisms to maintain life

CatabolismReleasing energy by

breaking down of larger molecules into

smaller onesDigestion

AnabolismStoring energy by

creating larger molecules from smaller ones.

Creating body fat

2 Types

Ch.8 – Cellular Energy 8.1 – How organisms obtain energy

All living cells use adenosine triphosphate (ATP) for capture, transfer, and storage of energy.


Each cell needs millions

of ATP molecules per

second in order to drive its

biochemical machinery

Autotrophsare able to create glucose from inorganic substances.

That glucose is broken down to form ATP molecules


Heterotrophsobtain glucose from digesting other living

things.That glucose is

broken down to form ATP molecules

Autotrophs

Heterotrophs

Ch.8 – Cellular Energy 8.2 – Photosynthesis

Carbon Dioxide + Water Light Glucose + Oxygen6 CO2 + 6 H2O Light C6H12O6 + 6 O2

The story of how living things make ATP starts with…



•The light reactions (in the thylakoids) split water, release O2, produce ATP, and form NADPH

•The Calvin cycle (in the stroma) forms sugar from CO2, using ATP and NADPH

•The Calvin cycle begins with carbon fixation, incorporating CO2 into organic molecules

3PGA

Glucose


Light Reaction Movie


Photosystem II• Light energy is used to split

an H2O molecule• When H2O splits

- O2 is released- protons (H+ ions) stay in

the thylakoid space &- an activated electron

enters the electron transport chain.


Electron Transport ChainElectrons are moved through

the thlakoid membrane and more protons are pumped into the thylakoid space


Photosystem I•Light reenergizes the electrons

•The reenergized electon is transferred to

NADP+ Reductase to form an NADPH from NADP+

Ch.8 – Cellular Energy 8.2 – PhotosynthesisChemiosmosis

• Protons build up in the thylakoid space and create a concentration gradient

• Protons then move across the thylakoid membrane through ATP synthase which causes ADP to convert to ATP

Light Reactions Animation

Ch.8 – Cellular Energy 8.2 – Photosynthesis1.What is the basic formula of photosynthesis?

2.How did plants acquire photosynthesis in evolution? Name three features of chloroplasts that are indicative of their origin. (It is referred to as endosymbiosis or the endosymbiotic theory) Click

3.Photosynthesis can be divided in two different processes. What are these processes? What are their products and reactants?

4.Oxygen is released during photosynthetic light reactions. Where is this oxygen coming from?

The splitting of H2O in Photosystem II


5.What is the driving force for ATP synthesis at the ATP synthase multi-protein complex?

6.Where do you find a higher pH value, inside or outside of the thylakoid?

7. Which process creates NADPH from NADP+?

Photosystem IEnergized e- are transferred to the enzyme

NADP+ Reductase



3PGA

Glucose

The Calvin Cycle (light independent reactions or the dark reactions)


Carbon Fixation3 CO2 combine with 3 5-C compounds to

form 6 3-C compounds called 3-PGA


ReductionEnergy from ATP and

NADPH is used to form

6 G3P molecules (high energy molecules)

From the 6 PGA molecules

1 G3P molecule leaves the cycle to form glucose, fructose

starches, etc.


RegenerationATP and the enzyme rubisco convert the 5

G3P to 3 RuBPThese molecules are

then ready to bond with 3 more CO2

Calvin Cycle Animation

Ch.8 – Cellular Energy 8.3 - Cellular respiration

Aerobic Respiration requires O2 to make ATP

from the energy stored in glucose

Cellular Respiration

Glucose + Oxygen Energy + Carbon Dioxide + Water

C6H12O6 + 6 O2 36/38 ATP + 6 CO2 + 6 H2O



Electron Transport Chain

Oxidative phosphorylation

1

23

The 3 Processes of cellular respiration

or Krebs Cycle

CO2

O2

H2O

2 2

32Or34


• Glycolysis (“splitting of sugar”) breaks

down glucose into two molecules of pyruvate

• Glycolysis occurs in the cytoplasm and has two major phases:

-Energy investment phase -Energy payoff phase

Net ATP = 2


Citric Acid Cycle or

Krebs Cycle

Before the citric acid cycle can begin, pyruvate must be converted to

Acetyl CoA

It takes place in the matrix of the mitochondria



Krebs Cycle

The acetyl group of acetyl CoA joins the cycle by combining

with the 4-C compound,

oxaloacetate, forming citric acid

(citrate)



Krebs Cycle

The next seven steps decompose the citrate back to oxaloacetate

The NADH and FADH2 produced by the cycle send electrons to the

electron transport chain


•e- from NADH & FADH2 pass through protein complexes in the cristae (inner membrane)•This causes H+ to be pumped out of the matrix

To give you an idea of how much ATP we require to survive…

We take in about 2 x 1020 molecules of O2 per breath200,000,000,000,000,000,000


•O2 diffuses into the matrix and bonds with the e- passing through the transport chain.

•H+ diffuses through ATP synthase back into the matrix (chemiosmosis) creating ATP (phosphorilation)

Ch.8 – Cellular Energy 8.3 - Cellular respirationMaking energy when there is no oxygen

Anaerobic Respiration or

Fermentation

It is essentially a cell just relying on glycolysis for its energy needs

Only produces 2 ATP per glucose molecule (not the 36 or 38 that aerobic respiration can create)

Other molecules are created through reactions that provide the NAD+ needed for glycolysis to occur

ATP can be created much faster than with aerobic respiration (just in smaller quantities)

CH3-C-C-OH

=O -O

CH3-CH

-O

CH3-CH2-OHCH3-CH-C-OH

-OH

=O

CO2CO2

Lactic Acid Fermentation

AlcoholicFermentation

2 ATP

2 ATP

4 ATP

4 ATP

CH3-C-C-OH

=O -O

CH3-CH-C-OH

-OH

=O


2 ATP

2 ATP

4 ATP

4 ATP

•Used by some fungi and bacteria & is used to make cheese and yogurt

•Human muscle cells use lactic acid fermentation to generate ATP when O2 is scarce

CH3-C-C-OH

=O -O

CH3-CH-C-OH

-OH

=O


2 ATP

2 ATP

4 ATP

4 ATP

•Used by some fungi and bacteria & is used to make cheese and yogurt

•Human muscle cells use lactic acid fermentation to generate ATP when O2 is scarce

CH3-C-C-OH

=O -O

CH3-CH

-O

CH3-CH2-OH

CO2CO2

AlcoholicFermentation

2ATP2ATP 4ATP4ATP

Used by yeast and some bacteria & is used in brewing, winemaking, and baking