## Energy and Metabolism

Metabolism is defined as the sum of all chemical reactions that take place in an individual. This abstract concept lays the foundation for understanding how biological systems acquire and use energy.

Metabolic processes either use energy to build large molecules from smaller precursors (anabolism), or they release energy by breaking down large molecules into smaller products (catabolism). Catabolic processes involve breaking down large biomolecules and capturing the energy contained within those molecules for other purposes. Anabolic processes involve the synthesis of large biomolecules from smaller precursors. With a little effort, you might begin to see that anabolic processes require energy . . . while catabolic processes provide the needed energy. They are thus intimately linked and the sum of all these pathways is referred to as “metabolism.” Examine this figure to see a summary of energy and carbon flow in metabolism.

The source of almost all energy on the planet is the sun. This energy is harvested by plants and some microbes and stored in the simple sugar glucose through a process called photosynthesis. All living organisms consume glucose and combine it with oxygen to produce energy and carbon dioxide. The energy released is temporarily stored by the synthesis of a high energy compound called ATP. The energy released when ATP is broken down to ADP can be used to power many biological functions, such as muscle contraction. Many organisms, such as yeast, can utilize the energy stored in glucose without using oxygen. Fermentation produces less ATP then cellular respiration and can produce a variety of other end products. Yeast, for example, produce ethanol when they go through fermentation.

Both anabolic and catabolic chemical reactions are facilitated by enzymes, which are protein catalysts that enable chemical reactions that would otherwise be unlikely to occur. Enzymes work by decreasing the amount of energy required for a chemical reaction to occur. This is known as activation energy. You can visualize activation energy by thinking about the energy required for a skier to climb a hill before being able to effortlessly ski down the hill at high speeds. Enzymes decrease the activation energy required for a chemical reaction to occur.

## Part 1: Basal Metabolic Rate

How much energy do you expend in a single day? Each person expends a different amount of energy (expressed in units called Calories) to maintain his or her bodily functions. Your basal metabolic rate (BMR) is the total number of calories required to maintain only vital bodily functions. This number varies from person to person and is based on a number of factors including age, gender, height, weight, and aerobic fitness.

1. To determine your own BMR, you will need the following numbers:
1. Height (in inches) = ___________ Height (in centimeters) = ____________
2. Weight (in pounds) = __________ Weight (in kilograms) = _____________
2. Using the data in Table 1, calculate your total surface area (in meters squared): __________
3. Use Table 2 to determine the number of calories your body burns per m2 of surface area per hr. _____________
4. Calculate the number of calories you burn in 1 hour! (Calories/m2 × surface area) __________ This is your BMR!
Table 1. Surface area relationships for human beings of known height and weight. Values are in square meters (m2).
Weight (kg) Height (cm)
120 130 140 150 160 170 180 190 200 210 220
40 1.15 1.2 1.25 1.3 1.36 1.42 1.48 1.55
45 1.23 1.27 1.32 1.37 1.43 1.48 1.54 1.61
50 1.3 1.34 1.39 1.44 1.49 1.54 1.6 1.67 1.74
55 1.37 1.42 1.46 1.5 1.55 1.61 1.67 1.73 1.8
60 1.44 1.48 1.52 1.57 1.62 1.67 1.73 1.79 1.85 1.92
65 1.54 1.58 1.63 1.68 1.73 1.79 1.85 1.91 1.97
70 1.61 1.65 1.7 1.75 1.8 1.85 1.91 1.96 2.02 2.08
75 1.68 1.72 1.76 1.81 1.86 1.91 1.96 2.02 2.07 2.13
80 1.74 1.78 1.82 1.86 1.91 1.96 2.02 2.07  2.13 2.18
85 1.81 1.84 1.88 1.92 1.97 2.02 2.07 2.13 2.18 2.24
90 1.87 1.9 1.94 1.98 2.03 2.08 2.13 2.18 2.24 2.3
95 1.97 2.01 2.05 2.09 2.14 2.18 2.24 2.3 2.36
100 2.03 2.07 2.12 2.16 2.2 2.24 2.3 2.35 2.41
105 2.1 2.14 2.18 2.22 2.26 2.31 2.35 2.41 2.47
110 2.17 2.21 2.24 2.28 2.32 2.36 2.41 2.47 2.53
115 2.23 2.27 2.3 2.33 2.38 2.42 2.47 2.53 2.58
120 2.33 2.36 2.39 2.43 2.48 2.53 2.58 2.63
125 2.39 2.42 2.45 2.49 2.53 2.58 2.63 2.69
130 2.44 2.47 2.51 2.54 2.59 2.63 2.68 2.75
135 2.5 2.53 2.556 2.6 2.64 2.69 2.74 2.81
140 2.55 2.58 2.62 2.66 2.7 2.74 2.8 2.87
Table 2. Calories expended per unit surface area $\displaystyle\bigg{(}\frac{\text{Calories}}{m^2}\bigg)$
Age Male Female
1 53 53
2 52.4 52.4
5 49.3 48.4
10 44 42.5
15 41.8 37.9
20 38.6 35.3
25 37.5 35.2
30 36.8 35.1
35 36.5 35
40 36.3 34.9
50 35.8 33.9
60 34.9 32.7
70 33.8 31.7
80 33 30.9

## Part 2: Calorie Expenditure

If you were to lie in bed and not move a single muscle, except those required to keep you alive, you would burn only the number of calories you calculated in your BMR. Most of us don’t spend our time like this. For this next activity, you will calculate the number of calories you burn to do different activities. Your calculations will be based on your BMR, which you calculated in the previous part. Fill in the following chart.

Activity BMR
(Cal/hr)
Activity Expenditure Total Calories
(burned in 1 hr)
Sitting still (example) 70 + (  70   × 0.2) =   14   =    84
Sitting, writing ____ + (____ × 0.4) = ____ = _____
Standing, relaxed ____ + (____ × 0.5) = ____ = _____
Standing at attention ____ + (____ × 0.6) = ____ = _____
Singing ____ + (____ × 0.7) = ____ = _____
Dressing ____ + (____ × 0.8) = ____ = _____
Driving a car ____ + (____ × 0.9) = ____ = _____
Typing rapidly ____ + (____ × 1.0) = ____ = _____
Piano playing ____ + (____ × 1.4) = ____ = _____
House work ____ + (____ × 1.6) = ____ = _____
Walking (3 mph) ____ + (____ × 2.0) = ____ = _____
Carpentry ____ + (____ × 2.4) = ____ = _____
Dancing ____ + (____ × 3.8) = ____ = _____
Climbing upstairs ____ + (____ × 5.8) = ____ = _____
Swimming ____ + (____ × 6.0) = ____ = _____
Running (5 mph) ____ + (____ × 7.0) = ____ = _____
Rowing in a race ____ + (____ × 16.0) = ____ = _____

## Part 3: Do Energy Drinks Provide You With Energy?

Energy drinks are a popular beverage, especially amongst busy students and athletes. But do energy drinks really provide you with energy? If so, how do they do this?

In this part of the lab, you will investigate the marketing claims for four popular energy drinks:

• Red Bull® (from advertising materials)
• • is a functional product developed especially for periods of increased mental and physical exertion.
• • can be drunk in virtually any situation.
• • improves performance, especially during times of increased stress or strain.
• • improves concentration and reaction speed.
• • stimulates the metabolism.
• Lo-Carb Monster Energy® (from advertising materials)
• Tear into a can of the meanest energy supplement on the planet. We went down to the lab and cooked up a double shot of our killer energy brew.
• We hacked out the carbohydrates and calories, transplanted the “wicked buzz,” and dialed in the flavor.
• Lo-Carb MONSTER energy drink still delivers twice the BUZZ of a regular energy drink, but only has a fraction of the calories.
• This maximum energy supplement delivers an energy boost with a natural passion fruit flavor. It’s lightly carbonated with a clean smooth feel.
• This maximum energy supplement delivers an energy boost with a unique blend of natural energizing elements, including d-ribose, l-carnitine and taurine. It’s pure, concentrated energy in an 8.3 fluid ounce can.
• Impulse® Energy Drink contains special supplements to immediately enhance mental and physical efficiency and give you the energy boost you deserve . . . replenishing your strength.
• Impulse® Energy Drink gets its energy from a simple source: nutrients, minerals, and vitamins that occur naturally in the body and foods we eat. Enjoy: the wake-up power of caffeine, the alertness-inducing properties of taurine, the lift you get from vitamin B6 and B12. Combined with Impulse’s other ingredients, these are known to increase mental focus and physical well being, enhance performance, and accelerate metabolism.

### Lab Question

1. When we say something gives us “energy” what does that mean? What is a biological definition of energy?

Your instructor will give you the ingredient list for one of the energy drinks listed above. Your task is to evaluate and classify each ingredient on the list. Which ones actually provide energy to the human body? What is the physiological role of each ingredient? Provide a detailed analysis of your energy drink.

Place each ingredient from your energy drink into one of the following categories.

• Energy sources
• Amino acids
• Stimulants
• Vitamins
• Other

Summarize the other drinks: Red Bull®, Lo-Carb Monster Energy®, Sobe Adrenaline Rush®, Impulse®, and Coca Cola.

### Lab Question

1. Based upon the class analysis, which of the following “energy drinks” actually provides more energy per can than a 12oz can of Coca Cola®?