Photosynthesis and Cellular Respiration

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Photosynthesis and Cellular Respiration:

Photosynthesis and Cellular Respiration

Objectives Section 1:

Objectives Section 1 I can explain in detail the flow of energy through living systems I can compare the chemical processes of autotrophs and heterotrophs I can describe the role of ATP in metabolism I can describe how energy is released by ATP.


Metabolism Metabolism: all of the chemical reactions that take place within an organism Metabolic pathways alter molecules in a series of steps. Enzymes selectively accelerate each step. enzymes are regulated to maintain a balance of supply and demand.

PowerPoint Presentation:

Catabolic reactions give off energy by breaking down complicated molecules to simpler compounds. Anabolic reactions use energy to build complicated molecules from simpler compounds. The energy released by catabolic pathways is used to drive anabolic pathways.

Autotrophs vs Heterotrophs:

Autotrophs vs Heterotrophs Autotrophs make their own food through anabolic reactions Many autotrophs carry out photosynthesis Heterotrophs can not make their own food Heterotrophs must eat other organisms to obtain energy from food through catabolic reactions Heterotrophs utilize cellular respiration


ATP ATP powers cellular work A cell does three main kinds of work: Mechanical work, beating of cilia, contraction of muscle cells, and movement of chromosomes Transport work, pumping substances across membranes against the direction of spontaneous movement Chemical work, driving endergonic reactions such as the synthesis of polymers from monomers

PowerPoint Presentation:

ATP ( adenosine triphosphate ) is a type of nucleotide consisting of the nitrogenous base adenine, the sugar ribose, and a chain of three phosphate groups.

PowerPoint Presentation:

The bonds between phosphate groups can be broken by hydrolysis.

So what?:

So what? Energy is stored in these bonds. So? The breaking of the chemical bond releases the energy ATP + H 2 O → ADP + P + ENERGY

Cellular Respiration:

Cellular Respiration The process by which mitochondria break down glucose to make ATP In order for our bodies to use the energy, the food must be broken down into a usable form What is the usable form of energy? What type of process breaks down molecules?

Objectives Section 3 (yes, we skipped to section 3, for now):

Objectives Section 3 (yes, we skipped to section 3, for now) I can summarize how glucose is broken down in glycolysis. I can describe how ATP is made in cellular respiration. I can identify the role of fermentation in cellular respiration. I can evaluate the importance of oxygen in aerobic respiration.

Overall Reaction:

Overall Reaction C 6 H 12 O 6 + 6O 2 → 6CO 2 + 6H 2 O + 38 ATP Overall this is a three stage process Glycolysis: Occurs in the cytoplasm Glucose is broken down Krebs Cycle Breaks down pyruvate into CO2 Occurs in mitochondrial matrix E lectron T ransport C hain ATP is synthesized


Glycolysis Glyco = glucose Lysis = break down Occurs in the cytoplasm This stage occurs in BOTH aerobic and anaerobic respiration Glucose breaks down into 2 pyruvate (2 ATP are also made) Glucose is a 6-carbon sugar Pyruvate is a 3-carbon molecule (there are two of them) See diagram on simple explanation handout

Glycolysis Reactants and Products:

Glycolysis Reactants and Products Reactants 1 glucose Enzymes are needed 2 ATP are needed to start Products 2 Pyruvates (go to next step) 4 ATP (2 are gained) 2 NADH (go to ETC)

Intermediate step :

Intermediate step Pyruvate is converted to acetyl CoA Occurs in the cytoplasm See diagram on simple explanation handout

Intermediate step Reactants and products:

Intermediate step Reactants and products Reactants 2 pyruvate (from glycolysis) Products 2 Acetyl CoA (go to next step) 2 CO 2 (given off as waste) 2 NADH (go to ETC)

Krebs Cycle (Citric Acid Cycle):

Krebs Cycle (Citric Acid Cycle) Occurs in the matrix of mitochondria A series of reactions occur (this is not just one step) Main purpose is to generate electrons for use in ETC 2 ATP is given off See diagram on simple explanation handout

Krebs Cycle Reactants and Products:

Krebs Cycle Reactants and Products Reactants 2 Acetyl CoA Products 2 ATP 6 NADH (go to ETC) 2 FADH 2 (go to ETC) 4 CO 2 (given off as waste)

Electron Transport Chain:

Electron Transport Chain Occurs in inner membrane of mitochondria Series (chain) of coupled redox reactions (electrons are transported through the chain) Electrons carried to this step by NADH and FADH 2 (produced in previous steps) Oxygen is used in this step Water is given off

Electron Transport Chain Reactants and Products:

Electron Transport Chain Reactants and Products Reactants 10 NADH 2 FADH 2 Oxygen Products 34 ATP H 2 O

Where do we get 38 ATP?:

Where do we get 38 ATP? 2 ATP made in glycolysis 2 ATP made in Krebs Cycle 34 ATP made in ETC 1 NADH = 3 ATP 10 X 3 = 30 1 FADH 2 = 2 ATP 2 X 2 = 4

Anaerobic Respiration (Fermentation):

Anaerobic Respiration (Fermentation) Glycolysis Yields 2 pyruvate and 2 ATP With no oxygen present, cellular respiration does not occur ONLY 2 ATP ARE PRODUCED (compare to aerobic respiration)

Two Types of Fermentation:

Two Types of Fermentation Alcoholic Fermentation Pyruvate converted to ethyl alcohol and CO 2 Carried out by yeast and some bacteria Used in producing alcohol (both consumable and for ethanol), and for baking Lactic Acid Fermentation Pyruvate converted to lactic acid Carried out by muscles when working hard (muscles need ATP but can’t get O 2 ) Causes muscle soreness and cramps


Photosynthesis Carried out by most (not all) autotrophs 6CO 2 + 6H 2 O + light energy→ C 6 H 12 O 6 + 6O 2 Basically this reaction is the OPPOSITE of cellular respiration See simple explanation handout and text

Steps of Photosynthesis:

Steps of Photosynthesis Light reaction (depends on light) Traps sunlight Produces electrons and ATP required to power the dark reaction Oxygen given off here Dark reaction, aka Calvin Cycle (does not directly depend on light) Uses ATP and electrons from light reaction and CO2 to make glucose See diagram on simple explanation handout

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