LEC: Energy Transformations in Living Organisms: Cellular Respiration

Biology Biology Science DepartmentScience DepartmentDeerfield High SchoolDeerfield High School

LEC: Energy Transformations in LEC: Energy Transformations in Living Organisms: Cellular Living Organisms: Cellular

RespirationRespirationUnit 3: Energy Transformations

Chapter 9, Sections 1 & 2 (Pages 220-232)


Review: Producers

Producers get their energy from the sun.

Producers convert this light energy into stored chemical energy (glucose).

This process is called photosynthesis.


Review: Consumers

Consumers get their energy from the producers.

Consumers convert stored chemical energy (glucose) into usable chemical energy (ATP).

This process is called cellular respiration.


Cellular Respiration (aerobic)

Cellular respiration is the process by which glucose (C6H12O6) is broken down to release energy for making ATP, another form of chemical energy.


Aerobic Respiration – Equation

C6H12O6 + 6 O2 6 H2O + 6 CO2 + 36 ATP

foodfood(glucose, a carbohydrate)(glucose, a carbohydrate)

oxygenoxygen waterwater carboncarbondioxidedioxide


BioTheme: Interdependence!

Photosynthesis:

6 H2O + 6 CO2 + energy (sun) → C6H12O6 + 6 O2

Aerobic Cellular Respiration:

C6H12O6 + 6 O2 → 6 H2O + 6 CO2 + energy (ATP))


Why ATP? An analogy to money…

Glucose in our food is a great source of energy! ($100 bill) However, individual cell processes may only require a small

amount of energy ($1 bill) Analogy: most vending machines do not accept $100 bills!

We need a smaller form of “currency” for these processes. ATP (adenosine triphosphate) is this important cellular

“currency” for life. ATP releases more appropriate amounts of energy for the

individual cellular processes that require energy.

(We will study this molecule in detail in our next activity!)


The BIG Question is…

Do only animals respire?

Or do plants respire too?

Only plants perform photosynthesis Plants AND animals perform cellular

respiration!

(Can you explain why??)


Site of Cellular Respiration

Plant and animal cells contain mitochondria: cell structures that transform chemical energy from glucose to ATP.


Significant ATP Production

Aerobic cellular respiration releases energy SLOWLY, using oxygen to convert ONE molecule of glucose to 36 ATP!


Cellular Respiration (anaerobic)

What happens when cells don’t have enough oxygen? Some organisms live in an oxygen-free environment.

How do they get their energy?


Cellular Respiration (anaerobic)

Anaerobic respiration is also called fermentation, or the process by which energy is released from glucose when oxygen is NOT available.

This process allows organisms to continue to produce energy until oxygen is available.

However, this process only releases 2 ATP per molecule of glucose.


Alcoholic Fermentation

Anaerobic way of converting energy for yeast and other microorganisms

Glucose broken down to produce alcohol, CO2 and energy (ATP)

C6H12O6 ethanol + CO2 + 2 ATP

EX: baking bread with yeast fermenting wine & beer


Fermentation - Bread

Source of sugar? DOUGH! (sugar and/or flour) Yeast use up the O2 and ferment sugar

Produce CO2, which is trapped within tiny bubbles & results in the dough rising

Produce ethanol, which evaporates in the baking process


Fermentation - Wine

Source of sugar? GRAPES! Yeast use up the O2 and ferment sugar

Produce CO2 (kept only in champagne)

Produce ethanol (% alcohol varies based on sugar content of grapes and # of fermentations)


Fermentation - Beer

Source of sugar? BARLEY! Yeast use up the O2 and ferment sugar

Hops are added as a preservative and for added flavor Produce CO2 and ethanol also

Various carbohydrates can be used to make alcohol – including wheat, rice, and potatoes!


Other side effects of fermentation?!

“Drunken Swedish moose drowns after fermented apple binge”

http://www.usatoday.com/news/offbeat/2006-11-24-moose_x.htm

“Drunk Moose Invade Seniors Home”http://www.wtopnews.com/index.php?nid=456&sid=620430


Lactic Acid Fermentation

Anaerobic way of converting energy in animal cells and some microorganisms

Glucose broken down to produce lactic acid, CO2 and energy (ATP)

C6H12O6 lactic acid + CO2 + 2 ATP

EX: muscle cells during strenuous exercise fermenting cheese, yogurt, sour cream


Strenuous Exercise

Lactic acid is produced by your muscle cells during rapid exercise when the body cannot supply enough O2 to tissues.

Without enough O2, the body is NOT able to produce all of the ATP that is required.

The buildup of lactic acid can cause painful burning in your muscles!


Minimal ATP Production

In the absence of oxygen, anaerobic respiration only releases 2 ATP for each molecule of glucose broken down.


Comparing ATP Production

First, your body breaks down glucose through aerobic respiration to produce 36 ATP per glucose molecule; however, this is a slow process.

When muscle cells cannot get enough O2 they break down glucose through lactic acid fermentation to produce 2 ATP per glucose…

Therefore, AEROBIC RESPIRATION is much more efficient in terms of ATP production – 36 ATP compared to 2 ATP!


Aerobic Training

Ex: long runs, biking, swimming

Can increase the size and number of mitochondria in muscle cells

Can increase the delivery of O2 to muscles by improving the heart and lungs


Anaerobic Training

Ex: sprints, strides, quick bursts of energy

Increase the glycogen levels in the muscles

Increase body’s tolerance to lactic acid

LEC: Energy Transformations in Living Organisms: Cellular Respiration

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