Energy In Living Systems

• Autotroph- Make their energy from inorganic compounds and sunlight.

Ex. PlantsPhotosynthesis- The process by

which plants convert light energy into chemical energy.

• Heterotrophs- Consume plants and animals, and break them down by a process known as cellular respiration.

• Cellular Respiration is similar to burning fuel, except, cellular respiration makes ATP which is needed by cells to carry out activities of the cell.

Organisms and Energy Use

• All living organisms use energy for all biological functions

• Cells do many activities.– Transport molecules across the cell

membrane– Make proteins– Copy DNA– Divide

• In order for a cell or a group of cells to perform any task Energy is needed

• Energy by definition is the ability to do “work”

• Thermodynamics is the study of how energy moves and changes form

Laws of Thermodynamics1. The law of conservation of energy

• Energy can not be created or destroyed only converted from one form to another.

• We eat food and our bodies convert the food to energy;

• The gas transfers the heat of the stove top then to the water in the pot causing it to boil.

Metabolism

• All chemical reactions within a cell are part of the cell’s metabolism

• A chemical reaction that produces a product that will be used in another chemical reaction is called a metabolic pathway. 2 types:

–An catabolic pathway – releases energy by cutting down or breaking down large molecules

–anabolic pathway builds new larger molecules.

–Both pathways result in a flow of energy

Photosynthesis

• Energy flows between organisms in an ecosystem as well as within individual organisms

• Photosynthesis is an anabolic pathway – Plants use light energy, carbon dioxide and

water to form glucose and oxygen– The glucose is a source of food for many

organisms – The oxygen is also used by a multitude of

organisms.

Photosynthesis (Autotrophs)

Stage 1: Energy is captured from sunlight.

This occurs in the chloroplasts of:

• Plants

• Algae

• Membrane of certain prokaryotes

Photosynthesis Equation

6CO2 + 6H2O → C6H12O6 + 6O2

Plants use the sugar:

• To make and store starch.

• Later the plant breaks down starch to make ATP

• Proteins and nucleic acids are assembled from

components of these sugars.

Stage One Absorption of Light

Referred to as “Light Reactions” or “Light Dependant”

Light is a form of radiation- Energy that travels through space.

Different types of radiation:

• Light & heat

• Different wavelengths are seen as different colors. See fig 5 page 98.

Visible light

• How does the human eye or a leaf absorb light?

• By using light absorbing substances called pigments.

• A pigment will absorb a certain wavelengths and reflect all others.

Pigments Found in Plants

• Chlorophyll a & b- Absorbs blue and red and reflects, green and yellow. This pigment is found in leaves and stems.

• Carotenoids- Absorbs the violet, blue and green. And reflect orange and yellow. This is why you see yellow , orange and red leaves in the fall. And the different colors in fruits.

Questions

1. What are the reactants in photosynthesis? What are the products?

2. Why is stage one in photosynthesis called the light reaction?

3.Name two pigments found in plants?

4. When we see colors, we are see those colors that are absorbed or reflected?

5. Do plants used absorbed energy or reflected energy to power photosynthesis?

Monday, December 5, 2011

• Do Now: It has been elucidated that plants contain chloroplasts a and b as well as, carotenoids. What is the advantage of containing more than one pigment?

• Objective: Analyze the light dependent reactions.

• Homework: 5.3 quiz.

Stage 1:Production of Oxygen

• The energy that is absorbed by the thylakoid in the chloroplasts heats up or “excites the electrons in the chlorophyll.

• The e- are used to power the second stage of photosynthesis.

• The e- have to be replaced in the chlorophyll so water is split producing H+ and O2

Stage 2 The Electron Transport

Chain• Electrons are passed back and forth

causing water molecules to split.• The splitting of water causes H+ ions to

accumulate in the thylakoid.• When they increase H+ increase inside

they flow with there concentration gradient (diffusion) creating a proton pump.

• The energy from this pump is used to add the third phosphate to ATP.

Electron Transport Chain

ATP is an energy storing molecule produced by the ETC.

At the same time ETC is producing another energy storing molecule.

A chemical known as NADP combines with the high energy H+ ----NADPH.

By the end of Stage two, ATP and NADPH both contain stored energy.

Questions

1. How do the e- in the thylakoid pigments get excited?

2. Once these e- move down the ETC how are they replaced?

3.Where is the energy in ATP stored?

4.How does NADP gain a H?

5. Where is the energy in NADPH stored?

Photosynthesis

• Done only by autotrophs

• Two phases

– Light reaction –

• Chloroplasts use pigments to capture (or absorb) light energy from the violet-blue section of the light spectrum and reflect green.

• The light reaction results in the production of 2 different energy storing molecules.

Stage 3

–The Calvin Cycle

•The 2 energy storing molecules (ATP & NADPH) produced in the light reaction are used to form the organic compound glucose

Carbon Fixation• CO2 Molecules are split and combine

with 6 five carbon molecules.This is known as carbon fixation.

• See p. 212. The cycle starts with 6 five carbon molecules and 6 one carbon molecules( from CO2)

• Uses 12 ATP and 12NADPH to make 1 six carbon sugar. The other carbons go back to the system.

Rate of Photosynthesis

• Water – Must adapt.

• Temperature for most plants (0-370C)

• Light intensity – light goes up photosynthesis goes up. When it reaches its maximum, increasing light does not affect the rate.

Cellular respiration

• Cellular respiration – catabolic

–Glucose is broken down

–Pyruvate and 4 ATP are made

–NADH and FADH are used to make ATP

Cellular Respiration

• Uses molecules such as glucose to make energy in the form of ATP

• Two stages– Glycolysis is anaerobic (does not require

oxygen)– Krebs cycle is aerobic (requires oxygen)

• The products cell respiration (carbon dioxide & water) are the reactants for photosynthesis.

Cellular Respiration

• In order to obtain energy from the food you eat. You convert the macromolecules to ATP this is known as cellular respiration.

• If you do this using oxygen you are performing aerobic respiration.

• If you do this without oxygen you are performing anaerobic respiration.

Chemical Formula

• Example: Breakdown of glucose.

• C6H12O6 + 6O2 → 6CO2 + 6H2O + ATP

Glycolysis- Stage 1

• Stage 1 does not use oxygen.

• 2 ATP molecules are used to power…….. ……

• The breakdown of (1) six Carbon molecule into (2) three carbon ions.

• Each of the (2) three carbon molecule contains 1 of the phosphates.

See fig. 11 on page 105

• The break up of this carbon compound releases some energy which adds an H+ to NAD making it NADH.

• This NADH uses it energy to bring two more phosphates to the party.

• Those 4 phosphates are now stored as 4 ATP molecules.

• So far, Cellular respiration seems to be efficient.

• You start out with 2 ATP molecules and end up with 4 ATP molecules.

• The purpose of glycolysis is to make two three carbon molecules called pyruvate.

• When oxygen is present the pyruvate moves into the mitochondria.

Questions

• 1. A metabolic process that requires oxygen is called?

• 2. The breakdown of glucose in the first stage of cellular respiration is known as ?

• 3. Stage one Starts out with _____ATP molecules and through a series of reactions ends up with ______. This is a net gain of _______.

Electron Transport Chain

• This next step occurs only when oxygen is present.

• The energy in NADH and FADH pass e- down the ETC. Very similar to the ETC in Photosynthesis.

• The H+ ions are pumped in and out of the inner mitochondrion membrane.

Thursday, December 16th

• Do Now: Examine figure 12 on page106. What part of photosynthesis does the Krebs's cycle resemble? How do the two cycles differ?

• Objective: Examine how ATP is made in the second stage of cellular respiration.

• Homework: Page 110 #1&2.

Krebs's Cycle – Stage 2

• Recall in stage one there were two three carbon molecules (Pyruvate).

• These substances enter the mitochondria and perform a series of reactions:

6 C → 5 C→ 4 C

• The purpose of the Krebs's cycle is to store energy in two molecules

• FAD + H2 → FADH2

• NAD +H → NADH

• All the energy that was in the glucose is now in these two molecules.

Aerobic Respiration

• This H+ action adds a P to ADP making ATP.

• This action is repeated and up to 34 ATP molecules are created in one event.

Questions

• 1. What is the second stage of cellular respiration called?

• 2. At the end of stage 2 where is the energy that was originally in the glucose molecule?

• 3. What step comes after stage 2 only if oxygen is present?

• 4. How many ATP molecules are made as the end result? How?

Friday, December 17th

• Do Now: Read page 109 Muscle Fatigue and Endurance Training. What happens to muscles when they run out of oxygen?

• Objective: Identify the role of fermentation in the second stage of cellular respiration.

• Homework: None

Fermentation

• When oxygen is not available to accept the electrons from NADH. The Pyruvate accepts the electron instead.

• When NAD gets rid of electrons it becomes NAD+ and is recycle to begin glycolysis again.

• This process allows 2 ATP molecules to be made instead of 34 in aerobic respiration.

1. Lactic Acid Fermentation

• By using pyruvate to accept the electrons instead of oxygen. The byproduct lactic acid is produced.

• Lactic acid is what causes burning in a runners muscles.

Alcohol Fermentation

• Occurs in Saccharomyces cerevisiae (yeast)

• Byproduct is Ethanol

• Also occurs in wine, beer , etc….