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Chapter 7 The Working Cell: Energy from Food. Do Now What do plants need to make sugar? What do...
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Transcript of Chapter 7 The Working Cell: Energy from Food. Do Now What do plants need to make sugar? What do...
Chapter 7
The Working Cell:
Energy from Food
Do Now
What do plants need to make sugar?What do animals get from plants?
7.1 Sunlight Powers Life
FoodWater CycleClimate
Why is the sun important to life?
Autotrophs autotroph: organism that
makes its own food: “self-feeder” Inorganic materials --> organic
materials photosynthesis: uses the su
n’s energy to convert to food Light(energy) + water + CO2 --
> sugar + O2
producers: produce organic molecules that serve as food for other organisms in the ecosystem
Heterotrophs
heterotrophs: organisms that can’t make food; “other eaters”
consumers: must obtain food by eating producers or other consumers depend on producers for
energy and materials for life and growth
Cellular Respiration
cellular respiration: chemical process that uses oxygen to convert the chemical energy stored in organic molecules into another form (ATP)food into energy
C6H12O6 + O2 --> H2O + CO2 + energy
Do Now
Take out your homework (7.1 & 7.2 CC)
HW: 7.3 CC
What is the equation for cellular respiration?
7.2 Food Stores Chemical Energy
energy: the ability to perform work
kinetic energy: the energy of motion
potential energy: energy stored due to an object’s position or arrangement gain potential energy the higher
you go against gravity thermal energy: random
molecular movement which causes collisions and heat energy used is provided by food
Chemical Energy
Chemical energy the potential to perform
work is due to the arrangement of atoms within the molecules
depends on the structure of the molecules
(carbs, fats, and proteins are rich in chemical energy)
sugar (high potential) carbon dioxide + water (kinetic energy)
Cellular Respiration is like a Car Engine
high chemical energy = glucose and oxygen (gasoline and oxygen)
“exhaust” = carbon dioxide and water
40% from food to work 60% thermal energy as heat =
100W light bulb calorie: amount of energy
required to raise the temperature of 1g water by 1 degree Celsius 1000 calories = 1 kcal = C (on food labels)
Do Now
Take out your homework4 people at a time take the survey on
the computers in the backhttp://www.surveymonkey.com/s/
59F79KY
7.3 ATP
ATP: adenosine triphosphate Adenosine = adenine + ribose Triphosphate = 3 phosphates
One phosphate is lost in a chemical reaction ATP --> ADP The molecule that accepts the phosphate undergoes a change (for work)
Work chemical work: building large
molecules Ex. Proteins ATP energy for dehydration
synthesis links AA mechanical work: contraction
of muscle ATP transfers P to proteins -->
change shape --> muscle cells contract
transport work: pumping solutes (ions) across a cellular membrane P --> change shape
ATP CycleATP is continuously
converted to ADPMuscle cell recycles
all ATP once a minute
10 million spent and regenerated per second
Do Now
What is the overall purpose of cellular respiration?
Homework: Work on video critique lyricsQuestions 1-12 on CR worksheet
Food to Oxygen
Relationship of Cellular Respiration to Breathing
aerobic: process that requires oxygenETC
Anaerobic: does not require oxygenGlycolysisfermentation
In Cellular Respiration…
Oxygen attracts electrons very strongly “electron grubber”
Carbon and hydrogen exert much less pull Several carbon-hydrogen bonds in sugar
Carbon and hydrogen change partners and bond with oxygen Electrons in these bonds “fall” toward oxygen and release energy
Ex. Burning sugar
7.5 CR Converts Energy
Mitochondria Envelope of 2 membranes;
inner and outer with space Inner membrane encloses
thick fluid (matrix) Enzymes and other
molecules built into inner membrane
Complex folding allows many sites of reactions to maximize ATP production
Metabolism
metabolism: a cell’s chemical processes
Metabolic PathwaySeries of reactionsSpecific enzymes
catalyzes each reaction
3 Stages of CR Glycolysis, Kreb
cycle, ETC and ATP synthase
Stage 1: Glycolysis “splitting of sugar”
Outside the mitochondria in the cytoplasm
1. 2 ATP molecules split a 6-carbon glucose in half and adds a phosphate to each C-C-C-P
2. Each 3-C molecule transfers electrons and H+ to a carrier molecule NAD+
3. NAD+ accepts 2 electrons and one H = NADH
4. “payback” = 4 new ATP molecules produced5. Result is 2 pyruvic acid molecules
Cycle Input Output ATP
Glycolysis Glucose Pyruvic acid
2
Krebs Acetyl CoA
(from pyruvate)
CO2 2
ETC Electrons, O2 H2O 34
Overall C6H12O6 + O2 CO2 + H2O +38
Stage 2: Krebs Cycle (Hans Krebs)
Finishes breakdown of pyruvic acid molecules to CO2 which releases more ATP Enzymes are dissolved in
the fluid matrix Pyruvic acid does not
take part in the Krebs cycle Diffuses into the
mitochondrion and loses a molecule of CO2
Converted to a 2-C compound = acetyl CoA (Acetyl coenzyme A )
Krebs Cycle Steps
1. Acetyl CoA molecules joins a 4-C acceptor molecule
2. Produce 2 more CO2 molecules and an ATP per acetyl CoA
3. NADH and FADH2 trap most of energy
4. The 4-C acceptor regenerates and cycle continues
Cycle Input Output ATP
Glycolysis Glucose Pyruvic acid 2
Krebs Acetyl CoA CO2 2
ETC Electrons, O2 H2O 34
Overall C6H12O6 + O2 CO2 + H2O +38
Stage 3: ETC and ATP Synthase
1. NADH transfers electrons from glucose to ETC
2. Each transfer in the chain releases energy which is used to pump H+ across the membrane Less concentrated to more Stores potential energy
ATP synthases: protein structures in mitochondria that act as miniature turbines
3. H+ rush back “downhill” through the ATP synthase Energy used to convert ADP to ATP
Cycle Input Output ATP
Glycolysis Glucose Pyruvic acid 2
Krebs Acetyl CoA CO2 2
ETC Electrons, O2 H2O 34
Overall C6H12O6 + O2 CO2 + H2O +38
Summary of Cellular Respiration
7.6 Fermentation fermentation: process that can make ATP without oxygen (only 2 ATP) anaerobic: environment without oxygen Fermentation makes ATP entirely from glycolysis
Not enough oxygen being supplied Produces waste product called lactic acid
Temporary build-up results in soreness & fatigue Eventually converts back into pyruvic acid
Fermentation in Microorganisms and plants
Yeast is forced to ferment sugar Produces alcohol and CO2, not lactic acid
Some fungi and bacteria produce lactic acid Transform milk into cheese and yogurt
Oxygen allows most energy from food Much more efficient 38 ATP (w/oxygen) vs. 2 ATP (w/out)