By Muhammad Asif Pu Pak

Muhammad Asif

1. I can explain in detail the flow of energy through living systems

2. I can compare the chemical processes of autotrophs and heterotrophs

3. I can describe the role of ATP in metabolism

4. I can describe how energy is released by ATP.

Muhammad Asif

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.

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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.

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Muhammad Asif

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

Muhammad Asif

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

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

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The bonds between phosphate groups can be broken by hydrolysis.

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Energy is stored in these bonds.So?The breaking of the chemical bond

releases the energyATP + H2O→ ADP + P +

ENERGY

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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?

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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.

Muhammad Asif

C6H12O6 + 6O2 → 6CO2 + 6H2O + 38 ATP Overall this is a three stage process1. Glycolysis:

• Occurs in the cytoplasm• Glucose is broken down

2. Krebs Cycle• Breaks down pyruvate into CO2• Occurs in mitochondrial matrix

3. Electron Transport Chain• ATP is synthesized

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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

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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)

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Pyruvate is converted to acetyl CoA

Occurs in the cytoplasm

See diagram on simple explanation handout

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Reactants 2 pyruvate (from

glycolysis)

Products 2 Acetyl CoA (go to

next step) 2 CO2 (given off as

waste) 2 NADH (go to

ETC)

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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 ETC2 ATP is given off

See diagram on simple explanation handout

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Reactants 2 Acetyl CoA

Products 2 ATP 6 NADH (go to

ETC) 2 FADH2 (go to

ETC) 4 CO2 (given off as

waste)

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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 FADH2 (produced in previous steps)

Oxygen is used in this step Water is given off

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Reactants 10 NADH 2 FADH2

Oxygen

Products 34 ATP H2O

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2 ATP made in glycolysis2 ATP made in Krebs Cycle34 ATP made in ETC

1 NADH = 3 ATPo 10 X 3 = 30

1 FADH2 = 2 ATPo2 X 2 = 4

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GlycolysisYields 2 pyruvate and 2 ATPWith no oxygen present, cellular

respiration does not occurONLY 2 ATP ARE PRODUCED

(compare to aerobic respiration)

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Alcoholic Fermentation Pyruvate converted

to ethyl alcohol and CO2

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 O2 )

Causes muscle soreness and cramps

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Carried out by most (not all) autotrophs

6CO2 + 6H2O + light energy→ C6H12O6 + 6O2

Basically this reaction is the OPPOSITE of cellular respiration

See simple explanation handout and text

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1. Light reaction (depends on light)• Traps sunlight• Produces electrons and ATP required to power

the dark reaction• Oxygen given off here

2. 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

Muhammad Asif