Unit 6 Notes - Cell Transport, Photosynthesis, & Cellular...

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Transcript of Unit 6 Notes - Cell Transport, Photosynthesis, & Cellular...

  • 3/28/17

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    S E C TI O N 1: C E LLU LA R R E S P I R A TI O N : A N O V E R V I E W

    Chapter 9: Cellular Respiration &

    Fermentation

    As we learned last chapter, energy from the sun is transformed into different forms. In this chapter you will learn how cellular respiration transforms the energy into a form that our cells are able to use.

    this chapter focuses on how cells use the energy stored in food molecules to make ATP

    Chemical Energy for Animals

    Cellular Respiration: is the process by which cells make energy for life processes. ¡ Cells take the carbon present in glucose & turn it into stable

    carbon dioxide & energy ÷ In simple terms, it is the process where our bodies break down

    foods and the cells convert stored chemical energy from the food into ATP, which is the energy the cells use

    ÷ ATP is the portable form of energy used inside of cells

    Cellular Respiration

    Cellular Respiration is basically the opposite of photosynthesis.

    ¡ The products of photosynthesis are the reactants of respiration.

    ¡ In other words, plants and animals work together!

    ¡ “biochemical pathway”

    Adenosine Tri-Phosphate

    ATP: is the main source of energy for cells.

    ¡ ATP is made of a nitrogen base, a sugar, and 3 phosphates

    ¡ Energy holds the 3rd phosphate to the other 2.

    ¡ When the 3rd phosphate is released, ATP becomes Adenosine Di- Phosphate (ADP).

    ¡ The “energy connector” is also released, and energy is available for cell processes.

    S E C TI O N 2 : TH E P R O C E S S O F C E LLU LA R R E S P I R A TI O N

    Chapter 9: Cellular Respiration &

    Fermentation

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    Cellular Respiration (ATP Production)

    Glycolysis is the first step in respiration. ¡ It yields a small amount of ATP. ¡ It then leads to 1 of 2 paths depending on the presence or absence

    of oxygen:

    ÷ Anaerobic Fermentation occurs if oxygen is absent. ¢ It yields no additional ATP.

    ÷ Aerobic Respiration occurs if there is oxygen present. ¢ It yields more ATP.

    • The amount of oxygen present determines how much ATP can be produced

    Glycolysis

    Glycolysis is complicated here’s what happens: ¡ It takes place in the cytoplasm of

    the cell. ¡ 1 molecule of glucose (sugar)

    enters. ¡ 2 molecules of pyruvic acid are

    made. ¡ 2 molecules of NADH are made ¡ 2 (net) molecules of ATP are made.

    Glycolysis Summary: the process that breaks down glucose to pyruvate, producing a small amount of ATP

    S E C TI O N 3 : F E R M E N TA TI O N

    Chapter 9: Cellular Respiration &

    Fermentation

    Anaerobic Respiration

    Fermentation occurs after glycolysis if there is no oxygen (in the absence of oxygen).

    ¡ No ATP is produced, but NAD+ is.

    ÷ NAD+ is used to keep glycolysis going.

    ¡ Other products are lactic acid or ethyl alcohol. ¡ Summary of Fermentation: Process that recycles

    NAD+ in the absence of oxygen so that carbohydrates can continue to be broken down to produce ATP. Occurs to enable glycolysis to continue

    Lactic Acid Fermentation

    Pyruvic acid (from glycolysis) is converted to lactic acid.

    This process occurs in muscle cells when you exercise very hard.

    ¡ It occurs when there is not enough oxygen.

    ¡ The increased acidity in the cell cytosol reduces the ability of muscles to contract.

    ¡ This causes muscle fatigue, pain, & cramping.

    Lactic Acid Fermentation

    Lactic acid fermentation is used in the manufacture of yogurt and cheese.

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    Alcoholic Fermentation

    Some plants and unicellular organisms use alcoholic fermentation rather than lactic acid fermentation.

    ¡ Ethyl alcohol fermentation is used in making beer and wine.

    ¡ It is also used by yeast in bread-making.

    ÷ The ethyl alcohol is burned off, and the CO2 bubbles make the bread rise.

    S E C TI O N 2 : TH E P R O C E S S O F C E LLU LA R R E S P I R A TI O N

    Chapter 9: Cellular Respiration &

    Fermentation

    Aerobic Respiration

    Our cells usually have oxygen available.

    ¡ This allows for aerobic respiration.

    ¡ Nearly 20 times the ATP can be produced (over glycolysis)!!!

    Aerobic Respiration

    Remember, we started with glycolysis which gave us 2 ATPs.

    Since we now have oxygen available, fermentation is skipped

    ¡ Remember the 2 Pyruvic acid molecules from glycolysis? ÷ The pyruvic acid enters the mitochondria (in eukaryotes) ÷ It is used to make 2 acetyl CoA, 2 NADH, & 2 CO2

    ÷ Your muscles don’t hurt as bad, and you can keep going longer! (Of course, you’re working at a slower rate.)

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    Aerobic Respiration

    Aerobic Respiration has 2 major stages:

    1. Krebs Cycle ÷ NAD+ is changed to NADH. ÷ FAD+ is changed to FADH2 ÷ In prokaryotes, this occurs in the cytosol. ÷ In eukaryotes, this occurs in the mitochondria.

    2. Electron Transport Chain ÷ NADH and FADH2 is used to make ATP.

    ¢ 1 NADH makes 3 ATP ¢ 1 FADH2 makes 2 ATP

    Krebs Cycle

    Pyruvic Acid (from glycolysis) is converted into Acetyl CoA to start the Krebs Cycle

    CO2, Hydrogen, and ATP are produced.

    Along with NADH and FADH2

    Krebs Cycle

    1 molecule of glucose makes 2 molecules of pyruvic acid, which makes 2 Acetyl CoA – Therefore, the Krebs cycle must turn twice. ¡ Only 2 ATPs are produced (the same as glycolysis).

    ¡ 6 NADH molecules and 2 FADH2 molecules are made. ÷ They drive the rest of aerobic respiration.

    Krebs Cycle Summary: a series of chemical reactions that break down Acetyl CoA, producing ATP & electron carriers that enter an ETC

    •http://highered.mcgraw- hill.com/sites/0072507470/student_view0/chapter25/animation__how_the_krebs_cy cle_works__quiz_1_.html

    Krebs Cycle

    Electron Transport Chain

    The ETC is the final stage of aerobic respiration. ¡ Up to 34 (net) ATPs are produced (this is the stage of

    aerobic respiration that produces the most ATP)

    The NADH & FADH2 produced previously during glycolysis, the conversion of pyruvic acid, & the Krebs Cycle are converted into ATP during this process

    Remember: ¡ 1 NADH = 3 ATP ¡ 1 FADH2 = 2 ATP

    Electron Transport Chain

    The electrons grab Hydrogen ions and throw them out of the mitochondrial matrix.

    The Hydrogen naturally wants to leak back in (by diffusion).

    This “leaking” helps turn ADP back into ATP.

    Oxygen is the final electron acceptor.

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    ETC Amount of Energy Produced The efficiency of aerobic respiration is roughly 66%.

    ¡ That may not seem like much, but your car is only about 25% efficient!!!

    Amount of Energy Produced

    Glycolysis is extremely inefficient!!!

    ¡ It is only about 3.5% efficient.

    ¡ It is enough to provide energy for some unicellular and very small multi-cellular organisms, though.

    ¡ Most of the energy is contained in pyruvic acid, not the 2 ATPs produced.

    Summarizing Cellular Respiration

    Reactants: glucose and oxygen

    Products: carbon dioxide, water, and energy

    C6H12O6 + 6O2 à 6CO2 + 6H2O + energy (Glucose + Oxygen à Carbon Dioxide + Water +

    Energy)

    Cellular Respiration cellular respiration - the process by which cells

    make ATP by breaking down glucose or other food molecules ¡as you can see, the equations for photosynthesis

    and respiration have similar pieces ÷photosynthesis produces glucose and cellular

    respiration uses it ÷photosynthesis removes CO2 from the

    atmosphere and respiration puts it back ÷photosynthesis releases O2 into the atmosphere,

    and cellular respiration uses it

    Organic Compounds (Glucose)

    Glycolysis 2 ATP & 2 NADH

    Pyruvic acid

    Oxygen Oxygen absent present

    Fermentation Aerobic Respiration

    The Krebs Cycle

    Electron Transport Chain

    ATP

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    What is the difference between cellular respiration & photosynthesis?

    They are backwards in chemical equation of each other Cellular respiration produces ATP as an end product

    while photosynthesis produces glucose(sugar) as an end product

    H2O CO2 O2 Glucose Energy (but different types)

    What do they have in common?

    There are 3 main steps in glycolysis. What are the starting & ending products for each step?

    In the first step, glucose is the starting product and two three-carbon sugars are the end products.

    In the second step the three-carbon sugars are the starting products and NADH are the ending products.

    In the third step, the modified three-carbon sugar from the second step is converted to pyruvate; four molecules of ATP are produced.

    What happens during the Krebs cycle as electrons pass down the electron transport chain? Where does this step take place?

    Energy is transferred into each molecule through which the electrons pass. The electrons are transported in the inner membranes of mitochondria.

    How does the ETC during the Krebs cycle affect the hydrogen ion concentra