Photosynthesis What happens during the process of photosynthesis? Why is ATP useful to cells? What...
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Transcript of Photosynthesis What happens during the process of photosynthesis? Why is ATP useful to cells? What...
PhotosynthesisWhat happens during the process of
photosynthesis?
Why is ATP useful to cells?
What role do pigments & electron carriers play in photosynthesis?
What are the reactants and products of photosynthesis?
What factors affect photosynthesis?
8.1 Energy & LifeEnergy is the ability to do work
Have to be able to obtain and use energy in many forms (light, heat, electricity, or chemical compounds)
One of the most important compounds that cells use to store and release energy is called adenosine triphosphate (ATP)
8.1 Chemical Energy & ATP
ATP is made up of: 1. Adenine 2. A 5-carbon sugar called ribose 3. 3 phosphate groups
Sometimes seen as ADP (has 2 phosphates instead of 3, and can store small amounts of energy)
8.1 Chemical Energy & ATP
ATP can easily release energy (by breaking chemical bonds) or store energy (by adding chemical bonds) between its phosphate groups to supply a basic energy source for all cells ADP will store energy when you add a phosphate ATP will release energy when you take away a
phosphate
8.1 Chemical Energy & ATP
How do we use the energy provided by ATP? Carry out active transport by pumping Na+ ions
out of cells and pumping in K+ ions Contract muscles Build proteins & respond to signals Breathe
8.1 Chemical Energy & ATP
ATP is NOT a good long-term storage molecule. Sugar molecules, like glucose, store 90 times the energy ATP does Heterotrophs (?) & Autotrophs (?) therefore
are always looking to take in/make sugar or carbs to power their cells
8.2 Photosynthesis: An Overview
Energy from the sun travels to Earth in the form of light. Plants gather it in light-absorbing molecules called pigments Plants principal pigment is chlorophyll
Chlorophyll a & b are present, and capture blue-violet and red regions of the color spectrum
8.2 Photosynthesis: An Overview
Photosynthesis takes place inside organelles called chloroplasts, which contain many thylakoids arranged in stacks Chlorophyll are found inside the thylakoid
membranes The fluid portion of the chloroplast is known as
the stroma
8.2 Photosynthesis: An Overview
When chlorophyll absorbs light, a large fraction of that light energy is transferred directly to electrons in the chlorophyll molecule An electron-carrier accepts
the electrons and transfers them, along with the energy, to another molecule
Photosynthesis electron-carrier is known as NADP+
8.2 Photosynthesis: An Overview
Photosynthesis uses the energy of sunlight to convert water and carbon dioxide (reactants) into high-energy sugars and oxygen (products) 6CO2 + 6H2O C6H12O6 + 6O2 (light)
8.2 Photosynthesis: An Overview
Photosynthesis involves 2 kinds of reactions: Light-dependent reaction
Requires light and water (for electrons & hydrogen ions)
Occurs in the thylakoidsOxygen is released as a byproduct
Light-independent reactionDoesn’t require lightRequires carbon dioxide, ATP & NADPHOccurs in the stromaCreates sugars and carbs
Let’s Get Funky!Create a song / rap / act / drawing showing the
process of Photosynthesis. Your creative imagination should include: Light Leaf Chloroplast Thylakoid Chlorophyll Excited Electron NADP+ Sugar
*** If you are doing an act, you MUST have a narrator!!
9.1 Cellular Respiration: Overview
Organisms get the energy they need from food How much energy
depends on the kind of food
Energy is measured in calories: the amount of energy needed to raise the temperature of 1 gram of water by 1 degree CelsiusFats: 9 calories per
gramCarbs & Proteins: 4
calories per gram
9.1 Chemical Energy & Food
Food must be broken down gradually to control the release of energy and create compounds such as ATP to directly power the cell If we broke down food all at once, most of the
energy would burn away in the form of heat
9.1 Cellular Respiration: Overview
Cellular respiration is the process that releases energy from food in the presence of oxygen 6O2 + C6H12O6 6CO2 + 6H2O + Energy Notice anything??
9.1 Cellular Respiration: Overview
Cellular respiration has 3 main stages: 1. Glycolysis: creates very little energy 2. Krebs cycle: creates a little more energy 3. Electron transport chain (ETC): creates the
majority of the energy ; directly involves the world’s most powerful electron acceptor - Oxygen
9.1 Cellular Respiration: Overview
Aerobic
Requires oxygen
Ex: Electron Transport Chain
Anaerobic
Doesn’t require oxygen
Ex: Fermentation
** Glycolysis & Krebs don’t DIRECTLY use oxygen, but are involved with products/reactants of oxygen
9.1Where Do These Processes Occur?
Cytoplasm
Glycolysis
Mitochondria
Krebs Cycle
Electron Transport Chain (ETC)
9.1 Cellular Respiration: Overview
Cellular respiration is balanced by photosynthesis: the equations are reverse of each other One processes gives the reactants of the other
9.2 GlycolysisThe first set of reactions in cellular respiration
is Glycolysis (sugar-breaking). During glycolysis: 1 molecule of glucose (6 carbon molecule) 2
molecules of pyruvic acid (3 carbon molecule) Uses NAD+ as an electron acceptor to become
NADH Remember, Glycolysis doesn’t require oxygen!
9.2 Krebs CycleDuring Krebs, pyruvic acid is broken down into
carbon dioxide in a series of energy-extracting reactions Also known as the citric acid cycle Pyruvic acid is converted into acetyl-coA and
then into citric acid One molecule of glucose = 2 turns of the cycle Uses NAD+ & FAD as electron acceptors NADH
and FADH2
9.2 ETCThe electron transport chain uses high-energy
electrons from glycolysis & Krebs cycle to convert ADP & ATP NADH & FADH2 release their electrons, and as
they pass down the line, they generate energy to spin something known as ATP synthase
With each rotation, the enzyme grabs an ADP molecule and attaches a phosphate group, producing ATP
Oxygen is directly involved here
Let’s VisualizeCreate a table that lists the 3 steps of cellular
respiration and include:Where does it take place?
Directly requires oxygen?
What are the reactants?
What are the products?
Glycolysis
Krebs Cycle
ETC
9.2 Cellular RespirationAll together, cellular respiration produces about
36 ATP, water, and carbon dioxide. The rest of the energy is lost in the form of heat
9.3 Fermentation In the absence of
oxygen, fermentation releases energy from food molecules by producing ATP
Cells convert NADH to NAD+ by passing high-energy electrons back to pyruvic acid in the cytoplasm
2 types: Alcoholic and Lactic Acid Fermentation
9.3 FermentationAlcoholic
Used by yeasts & microorganisms
Causes bread dough to rise
Pyruvic acid + NADH Alcohol + CO2 + NAD+
Lactic Acid
Used by bacteria & humans (when?)
Creates cheese, yogurt, buttermilk
Pyruvic acid + NADH Lactic acid + NAD+
9.3 Fermentation3 main sources of ATP:
ATP already in the muscles: few seconds of intense activity
ATP made by lactic acid fermentation: short quick bursts of energy
ATP made by cellular respiration: exercise longer than 90 seconds