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Cellular Respiration. How do you know when you need to eat?. How do you feel when you are hungry? Empty stomach Dizzy Weak Sensations vary from person to person but the bottom line is…. How do we get the energy from food?????. Through cellular respiration!.
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How do you know when you need to eat? • How do you feel when you are hungry? • Empty stomach • Dizzy • Weak Sensations vary from person to person but the bottom line is…
How do we get the energy from food????? • Through cellular respiration!
So what is cellular respiration? • Cellular respirationactually consists of morethan two dozen chemical reactions. Many of the reactions take place in specialized organelles—mitochondria • Process releases energy by breaking down glucose (sugars) and other food molecules in the presence of oxygen. • This process occurs in all eukaryotic cells. • 6O2+C6H12O6 6CO2 + 6H2O + energy
Mitochondria a close up 2 membranes Cristae – folds of the inner membrane Matrix - liquid
Overview of cellular respiration • There are three main stages! • Glycolysis • Krebs cycle • Electron transport chain
A Road Map for Cellular Respiration The three main stages of cellular respiration: • Glycolysis happens in the cell’s cytoplasm • the Krebs cycle happens in the matrix • electron transport and ATP synthase happens on the inner membrane Mitochondria are the sites of 2 stages of cellular respiration.
Cell Respiration Overview • Because oxygen is required for cellular respiration it is known as an aerobic process. • Always starts with glycolysis! • From there it depends on whether oxygen is present or not!
First Step : Glycolysis • Happens in cytoplasm • Does NOT require oxygen • Takes glucose (6C) and breaks it down into 2 pyruvic acids (3C) • Needs 2 ATP molecules • Makes 4 ATP molecules and 2 NADH energy molecules • Overall only 2 ATP molecules are made because 2 ATP molecules are used in the process
Glycolysis • Occurs quickly- cells can produce thousands of ATP molecules in milliseconds!
Results of Glycolysis • So what was your reactant? • Glucose • What were your products? • 4 ATP • 2 NADH • 2 pyruvic acid molecules • What was your net gain of ATP? • 2 ATP • So how much energy was used? • 2 ATP
What is ATP? • Chemical fuel of the cell • Made up of • 5 carbon sugar • 3 phosphate groups • Nitrogenous base- Adenine • ATP is which type of macromolecule? • Nucleic acid
ATP Adenine Ribose 3 Phosphate groups
More What is ATP and ADP? • When the bond breaks between the 2nd and 3rd phosphate groups of ATP, energy is released and ADP is formed. • When a phosphate is given away it becomes ADP (adenosine diphosphate) • ADP can be turned back into ATP when a phosphate group binds to ADP
What is the difference between ATP and ADP? • ATP – adenosine triphosphate • Has 3 phosphate groups • ADP – adenine diphosphate • Only has 2 phosphate groups
Figure 8-3 Comparison of ADP and ATP to a Battery Section 8-1 ADP ATP Energy Energy Partially charged battery Fully charged battery
Krebs Cycle • Happens after glycolysis • Happens in the mitochondria • Oxygen has to be present!
Figure 9–6 The Krebs Cycle Section 9-2
So What is Made in the Preparation of the Krebs Cycle and the Krebs Cycle? • The tally of products from 2 molecules of pyruvic acid is • 8 NADH • 2 FADH2 • 2 ATP • 6 CO2
What are NADHand FADH? • They are compounds that accept electrons in the form of hydrogen. • They store the electrons and transport them to the electron transport chain. • So they are electron carriers! • We will use the energy from themlater on!
Final Step : Electron Transport Chain and ATP Synthase Action • The final stage of cellular respiration occurs in the inner membranes of mitochondria. This stage has two parts: • Electron transport chain • ATP production by ATP synthase.
Electron Transport Chain (ETC) • Happens in the mitochondria in the cristae • Oxygen has to be present • The Electron Transport Chain is made up of a series of carrier proteins located in the inner membrane of the mitochondria. • As electrons are passed along, H+ is pumped out of the inner membrane.
Figure 9–7 Electron Transport Chain Section 9-2 Electron Transport Hydrogen Ion Movement Channel Mitochondrion Intermembrane Space ATP synthase Inner Membrane Matrix ATP Production
ATP Synthase (the final final step) • ADP needs to turn back into ATP • The enzyme ATP Synthase performs Phosphorylation (the chemical reaction that makes ATP) • H+ ions move through these to make ATP. • Lots of ATP are made
So what are the products of ETC and ATP Synthase(Phosphorylation)? • Water • Lots of ATP is made • About 36-38 ATP • WOW! • http://vcell.ndsu.nodak.edu/animations/etc/movie.htm
Total ATP • Glycolysis – 2 ATP • Krebs – 2 ATP • Electron transport chain – 36-38 ATPs
Flowchart Section 9-2 Cellular Respiration Glucose(C6H12O6) + Oxygen(6O2) Glycolysis KrebsCycle ElectronTransportChain Carbon Dioxide (6CO2) + Water (6H2O)
What happens when oxygen is not present? • Glycolysis still occurs but Krebs and ETC will not. • Anaerobic respiration – respiration then occurs when no oxygen is present • This is called FERMENTATION! • So if fermentation occurs, Krebs will not.
Fermentation • Happens when there is no oxygen • Fermentation allows for small amounts of ATP to be made. • There are 2 types
Lactic Acid Fermentation • Occurs when oxygen cannot reach the cells fast enough • Pyruvic acid gets changed into lactic acid • Leads to sore muscles
Alcohol Fermentation • Pyruvic acid gets changed into alcohol • Wine and beer
Figure 9–4 Lactic Acid Fermentation Section 9-1 Lactic acid Glucose Pyruvic acid
Autotrophs and Heterotrophs • Autotrophs – organisms that can make their own food • Example? • Heterotrophs – organisms that cannot make their own food • Example?
Photosynthesis • Plants use the energy from sunlight to change H2O and CO2 into carbohydrates and O2 • 6H2O + 6CO2+ Light EnergyC6H12O6+ 6O2 • Happens in the chloroplast
Chloroplast • Has 2 membranes • Chlorophyll – green pigment that traps sunlight and allows for photosynthesis (leaves)
Photosynthesis: Reactants and Products Section 8-2 Light Energy Chloroplast CO2 + H2O Sugars + O2
Light CO2 Sugars O2 Figure 8-7 Photosynthesis: An Overview Section 8-3 Chloroplast Chloroplast NADP+ ADP + P Light- Dependent Reactions Calvin Cycle ATP NADPH
Light and Pigments • For photosynthesis to occur, light and pigments are needed. • Plants gather the sun’s energy with pigments • Chlorophyll a and chlorophyll b are the main ones • Both absorb in the blue-violet and red region but reflects the green • That is why the leaves are green!!!!
Light and Pigments • Besides chlorophyll a and b, plants also contain the pigment carotene. • Carotene is a red and orange pigment
Parts of Photosynthesis • Have two major reactions – • Light dependent reactions – need light • Calvin cycle (dark reactions) – don’t need light
Electron Carriers • When electrons become excited from the light energy, the excited electrons need a carrier • Carrier molecule – compounds that accept a pair of high energy electrons and transfer them to another molecule • Electron carrier - NADPH
Light Dependent Reactions • Light is needed • ATP, NADPH (electron carrier), and oxygen are made
Steps to the Light Dependent Reactions • Pigments in the chloroplast absorb light • This causes the electrons to become excited and so this increases their energy level. • The high energy electrons get trapped and are sent to the electron transport chain!
Figure 8-10 Light-Dependent Reactions Section 8-3 Hydrogen Ion Movement Chloroplast Photosystem II ATP synthase Inner Thylakoid Space Thylakoid Membrane Stroma Electron Transport Chain Photosystem I ATP Formation
Light Dependent Reactions 4. New electrons need to replace the stolen ones. • The new electrons come from the H in water. • The O2 left over is released into the air 5. The captured electrons go are energized and go through the electron transport chain. 6. As electrons moved through the chain, H+ ions are pumped across a membrane 7. Pigments again use the energy from light to reenergize electrons so that NADPH can be made.