Chapter 8 Cellular Energy. Section 1 How Organisms Obtain Energy

Chapter 8

Cellular Energy

Section 1

How Organisms Obtain Energy

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

Section 1: How Organisms Obtain Energy

KWhat I Know

WWhat I Want to Find Out

LWhat I Learned


Transformation of Energy

• Cellular processes require ____________– the ability to do work.

• _______________is the study of the flow and transformation of energy in the universe.



Laws of thermodynamics

• First law—the law of conservation of energy: energy can be converted from one form to another, but it cannot be created nor ______________.

• Second law: energy cannot be converted without the loss of usable energy, that is, _________________—disorder or unusable energy--increases.



Autotrophs and Heterotrophs• Directly or indirectly, nearly all the energy for life comes from the

Sun.

• _____________make their own food, either with energy from the sun or from inorganic substances.

• ________________ingest other organisms to obtain energy.


Metabolism• All of the chemical reactions in a cell are referred to as the cell’s

_________.

• A series of chemical reactions in which the product of one is the substrate for the next is called a metabolic pathway.

• _________pathways release energy by breaking down larger molecules.

• _____________pathways use energy to build larger molecules.


Metabolism• ________________– anabolic pathway in which light energy from the

Sun is converted to chemical energy for use by the cell

• ___________________– catabolic pathway in which organic molecules are broken down to release energy for use by the cell


ATP: The Unit of Cellular Energy• In living things, chemical energy is stored in biological molecules.

• ___________________(ATP) is the most important biological molecule that provides chemical energy.


ATP: The Unit of Cellular Energy

ATP structure

• Most abundant ____________-carrier in cells

• __________made of an adenine base, a ribose sugar, and three phosphate groups


ATP: The Unit of Cellular Energy

ATP function

• Releases energy when the bond between the second and third phosphate groups is broken.

• Transforms into a molecule called adenosine diphosphate (_____) and a free phosphate group.

ATP

• When chlorophyll absorbs light, it is absorbing energy

• It stores it in the __________ of Adenosine Triphosphate (ATP)

ATP, continued.• Carbs are most commonly broken down to make ATP.

• Breakdown of glucose yields ____ ATP.

• ATP = Energy currency of the cell.

• Cells use ATP for functions such as building molecules & moving materials by ______________.

• ATP releases energy when phosphate group released.

• Becomes Adenosine DiPhosphate (_____).– Can be converted back to ATP by adding phosphate.

ATP vs. ADP

ATP ADP Cycle

Essential Questions• What are the two laws of thermodynamics?

• What is the difference between an anabolic pathway and a catabolic pathway?

• How does ATP work in a cell?


Section 2

Photosynthesis

Light energy is trapped and converted into chemical energy during photosynthesis.

Section 2: Photosynthesis

KWhat I Know


LWhat I Learned

Photosynthesis

Overview of Photosynthesis• Most autotrophs make organic compounds using __________________.

• Photosynthesis is the process of converting ________energy into chemical energy.

THE FORMULA, continued.

http://www.gamequarium.org/cgi-bin/search/linfo.cgi?id=7688

Photosynthesis

Overview of Photosynthesis• Photosynthesis occurs in ______phases.

• In the _____________ phase, light energy is converted into chemical energy.

• In the ______________ phase, chemical energy used to synthesize glucose.

Photosynthesis

Phase One: Light Reactions

• The absorption of ____________is the first step in photosynthesis.

• Once light energy is captured, it can be stored as _______or NAPDH.

Photosynthesis


Chloroplasts• Are organelles that capture light energy

• Contain two main compartments:

• ________________: flattened saclike membranes • Stacks of thylakoids are called grana.

• The fluid filled space outside the grana called the __________________

Chloroplast structure

Photosynthesis


Pigments• Light-absorbing colored molecules called ________are found in the

thylakoid membranes.

• Different pigments absorb specific wavelengths of light.

• Most common pigment in plants is _________________.

• Plants also have accessory pigments.

Photosynthesis


Electron transport• The thylakoid membrane has a large surface area, providing space

for a large number of electron transporting molecules and two types of protein complexes called _____________________.

• Photosystems house the light-capturing pigments.

Photosynthesis


Electron transport• Light energy excites electrons in _______________________.

• This light energy causes a water molecule to split – releasing an electron into the electron transport system, a hydrogen ion (H+ or proton) into the thylakoid space, and oxygen as a waste product.

Photosynthesis


Electron transport• The activated electrons move from photosystem II to an acceptor

molecule in the __________________membrane.

• The electron acceptor molecule transfers the electrons along a series of electron carriers to photosystem I.

Photosynthesis


Electron transport• In the presence of light, photosystem I transfers the electrons to a

protein.

• The protein transfers the electrons to the carrier molecule _________forming the energy storage molecule NADPH.

Photosynthesis


Electron transport• ATP is produced in conjunction with the electron transport system through

chemiosmosis

• ATP is produced through the flow of electrons _____a concentration gradient

• The breakdown of water provides the necessary protons for _____synthesis

Photosynthesis

Phase Two: The Calvin Cycle (light independent reactions)• In the second phase of photosynthesis, called the ___________, energy is

stored in organic molecules such as ____________.

Photosynthesis

Phase Two: The Calvin Cycle• The first step of the Calvin cycle is called ____________ fixation.

• CO2 molecules combine with 5-carbon molecules to form 3-phosphoglycerate (3-PGA)

Photosynthesis

Phase Two: The Calvin Cycle• In the second step, chemical energy stored in ATP and NADPH is

transferred to the 3-PGA to form glyceraldehyde 3-phospate (_________).

Photosynthesis

Phase Two: The Calvin Cycle• In the third step, some G3P molecules leave the cycle to be used

for the production of _________________and other organic compounds.

Photosynthesis

Phase Two: The Calvin Cycle• In the fourth and final step, an enzyme called ______converts the

remaining G3P molecules into 5-carbon molecules called ________1,5-bisphospates (RuBP).

• These molecules combine with new CO2 and continue the cycle.

2 Main steps of PS - Summary1. Light reactions—occurs only in the presence

of ___________– Occurs in the grana (thylakoids) of the

chloroplasts– Also known as Photolysis because light is used to

__________ _________ molecules into hydrogen and oxygen

2 Main steps of PS - Summary2. Dark Reactions—can occur in light ____ darkness. Follows light reactions

– Occurs in the stroma of the chloroplasts– Also known as Carbon fixation because CO2 will get

“fixed up” with the hydrogens and energy from the light reaction

Light ReactionsTake place within the membrane of the

thylakoid.1. Chlorophyll absorbs energy from sunlight.

– Water is __________ _________– Oxygen is ______________

2. Oxygen leaves the plant and goes into the air

The Dark Reactions

Occur in stroma of chloroplasts.1. _________ is added to a cycle of

reactions to build larger molecules

2. A molecule of simple sugar is formed– _____________

Photosynthesis

Alternative Pathways

C4 plants

• The C4 pathway allows plants to maintain photosynthesis while reducing _________ loss.

• Significant structural modification in the arrangement of cells within the leaves – separate CO2 uptake from location of Calvin cycle

Photosynthesis

Alternative Pathways

CAM plants

• Crassulacean acid metabolism (________) is found in desert plants.

• Collect CO2 at night and store it in organic compounds

• During the day, release CO2 from organic compounds for the light-dependent cycle of photosynthesis

Essential Questions• What are the two phases of photosynthesis?

• What is the function of a chloroplast during the light reactions?

• How can electron transport be described and diagramed?

Photosynthesis

Section 3

Cellular Respiration

Living organisms obtain energy by breaking down organic molecules during cellular respiration.

Section 3: Cellular Respiration

KWhat I Know


LWhat I Learned

Overview of Cellular Respiration• Organisms obtain energy in a process called _________________.

• Respiration harvests electrons from organic molecules and uses the energy to make _____________.

• The equation for cellular respiration is the opposite of the equation for ___________________:


Overview of Cellular Respiration • Cellular respiration occurs in two main parts: glycolysis and aerobic

respiration.

• Glycolysis is an ________ process, meaning it does not require ______.

• Aerobic respiration involves the ______cycle and electron transport.

• Aerobic processes require oxygen.


Glycolysis

• Glucose is broken down in the cytoplasm through the process of _______________.

• ____molecules of ATP and ____ molecules of NADH are formed for each molecule of glucose that is broken down.


Krebs Cycle• Glycolysis has a net result of _____ATP and ______pyruvate.

• Most of the energy from the glucose is still contained in the pyruvate.

• In the presence of oxygen, pyruvate is transported into the mitochondrial matrix, where it is converted into carbon dioxide.

• The series of reactions in which pyruvate is broken down into carbon dioxide is the ______________, also know as the tricarboxylic acid (TCA) cycle


Krebs Cycle

Steps of the Krebs cycle

• Prior to the Krebs cycle, pyruvate reacts with coenzyme A (CoA) to form ___________.

• Acetyl CoA moves into the mitochondrial matrix.

• Acetyl CoA combines with a 4-carbon compound to form citric acid.


Krebs Cycle

Steps of the Krebs cycle

• ______acid is broken down releasing two molecules of carbon dioxide and generating one ATP, three NADH, and one FADH2.

• Finally, acetyl CoA and citric acid are generated and the cycle continues.


Steps of Kreb’s1. Pyruvate broken down 2. Coenzyme A3. Citric acid formed4. Citric acid broken down5. 5-carbon molecule broken down6. 4-carbon molecule rearranged

Up to 38 ATP molecules are made from the breakdown of 1 glucose molecule.

Electron Transport• In aerobic respiration, electron transport is the final step in the

breakdown of ____________.

• NADH and FADH2 from the Krebs cycle are used to convert _____to _____.

• Electron transport and chemiosmosis in aerobic respiration are similar to the processes of photosynthesis.


Electron Transport

Prokaryotic cellular respiration

• Some prokaryotes undergo ___________respiration.

• They do not have mitochondria, so they use the ________membrane as the location of electron transport.


Steps of ETC - Summary1. Electrons removed – High energy electrons from

NADH & FADH2.

2. Hydrogen ions transported – High energy electrons travel through the proteins in the ETC.

3. ATP Produced – ATP synthase adds phosphate groups to ADP to make ATP. For each pair of electrons that passes through the ETC, 3 ATPs are made.

4. Water formed – Oxygen enters cellular respiration process & picks up electrons & hydrogen ions to form water.

Anaerobic Respiration• When oxygen is unavailable, cells cannot follow glycolysis with the

aerobic respiration (Krebs cycle and electron transport).

• The anaerobic process that follows glycolysis is anaerobic respiration, or ________________________.

• Fermentation occurs in the __________of the cell, and produces NAD+ and ATP.


Fermentation• Two types

– _______________ fermentation

– __________ ________ fermentation

Anaerobic Respiration

Lactic acid fermentation• Enzymes convert the pyruvate made during glycolysis into

_______acid.

• Skeletal muscles produce lactic acid when the body cannot supply enough oxygen, such as during periods of strenuous exercise.


Anaerobic Respiration

Alcohol fermentation • Occurs in _________and some bacteria

• Converts pyruvate into ethyl ________and carbon dioxide


PHOTOSYNTHESIS CELLULAR RESPIRATION

Organelle for process Chloroplast Mitochondrion

Reactants CO2 & H2O Sugars (C6H12O6) & O2

Electron Transport Chain Proteins within thylakoid membrane

Proteins within inner mitochondrial membrane

Cycle of chemical reactions Calvin cycle in stroma of chloroplasts builds sugar molecules

Krebs cycle in matrix of mitochondria breaks down carbon-based molecules

Equation 6CO2 + 6H2O C6H12O6 + 6O2 C6H12O6 + 6O2 6CO2 + 6H2O

Products Sugars (C6H12O6) & O2 CO2 & H2O

Photosynthesis & Cellular Respiration

Photosynthesis and Cellular Respiration


Essential Questions• What are the stages of cellular respiration?

• What is the role of electron carriers in each stage of cellular respiration?

• What are the similarities between alcoholic fermentation and lactic acid fermentation?


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Chapter 8 Cellular Energy. Section 1 How Organisms Obtain Energy