Chapter 8
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Transcript of Chapter 8
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
How Organisms Obtain Energy
Transformation of Energy
• Cellular processes require ____________– the ability to do work.
• _______________is the study of the flow and transformation of energy in the universe.
How Organisms Obtain Energy
Transformation of Energy
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.
How Organisms Obtain Energy
Transformation of Energy
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.
How Organisms 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.
How Organisms Obtain Energy
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
How Organisms Obtain Energy
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.
How Organisms Obtain 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
How Organisms Obtain Energy
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.
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?
How Organisms Obtain Energy
Light energy is trapped and converted into chemical energy during photosynthesis.
Section 2: Photosynthesis
KWhat I Know
WWhat I Want to Find Out
LWhat I Learned
Photosynthesis
Overview of Photosynthesis• Most autotrophs make organic compounds using __________________.
• Photosynthesis is the process of converting ________energy into chemical energy.
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
Phase One: Light Reactions
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 __________________
Photosynthesis
Phase One: Light Reactions
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
Phase One: Light Reactions
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
Phase One: Light Reactions
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
Phase One: Light Reactions
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
Phase One: Light Reactions
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
Phase One: Light Reactions
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
Living organisms obtain energy by breaking down organic molecules during cellular respiration.
Section 3: Cellular Respiration
KWhat I Know
WWhat I Want to Find Out
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 ___________________:
Cellular Respiration
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.
Cellular Respiration
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.
Cellular Respiration
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
Cellular Respiration
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.
Cellular Respiration
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.
Cellular Respiration
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.
Cellular Respiration
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.
Cellular Respiration
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.
Cellular Respiration
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.
Cellular Respiration
Anaerobic Respiration
Alcohol fermentation • Occurs in _________and some bacteria
• Converts pyruvate into ethyl ________and carbon dioxide
Cellular Respiration
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