Biology 2601A/B Lecture Notes - Lecture 7: Macromolecule, Laughing Gull, Basal Metabolic Rate

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Lecture 07: Energetics
Metabolism
The set of processes by which cells and organisms acquire, rearrange, and void commodities in ways
that sustai life
The su of all heial reatios i a iologial etit
- Metabolism is just what the organisms do with the energy it gets from food - it is just a descriptor of
what the organism is doing
- We care more about metabolic rate b/c we can use it to describe how an organism does metabolism
Metabolic Rate
A orgais’s rate of energy consumption; the rate at which it converts chemical-bond energy to heat
ad eteral ork
- Metabolic Rate = energy/time so it can be measured in watts
- Metabolism vs Metabolic rate A tree has a lot of metabolism but it has a low metabolic rate; taking
time into account is important
Measuring Metabolic Rate
How Do We Measure Metabolic Rate?
- BMR homeotherms in their thermoneutral zone means these
orgaiss are’t spedig a eerg to aitai their od
temperature so this is when their metabolic rate is measured
- SMR Poikilother’s od teperatures ar so the do’t hae a
thermoneutral zone. Instead, their metabolic rate is measured at a
standard temperature
- Resting Metabolic Rate Ideally based on basal or standard metabolic
rate, ut usuall it’s the best possible approximation
- Field Metabolic Rate All other measurements of metabolic rate are
done in the lab, but this measurement is done in the real world (this is
difficult)
- We take in food (chemical bond energy) interact it
w/oxygen and produce carbon dioxide, water, and energy.
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Direct Calorimetry Used to measure heat produced as a direct way of measuring metabolic rate
Indirect Calorimetry Works only for aerobic metabolism!
Accurate to 0.00001°C
- Direct calorimetry allows us to measure the heat produced by an animal.
This heat produced is a direct reflection of metabolic rate
- Small animal is in a jacketed chamber and it is melting ice because it
produces heat. We measure the amount of ice that is converted into water
and b/c we know the energetic cost of the ice to water transition, we can
say that because x amount of water was produced, y amount of heat was
released by the animal.
- Animals must be really small (i.e. small insects)
- From the amount of O2 consumed or the amount of CO2 produced, we can
estimate how much energy was associated with this reaction
- We can measure the O2 consumed for large animals (ex. We can measure
VO2 max in humans, but this is he e are atie ad ot restig so it o’t
give us a measurement for basal metabolic rate)
- For insects, measuring oxygen is really difficult (you have to do it with an
electrode and chemical reaction which uses redox reactions to measure the
amount of oxygen in the air), so we measure carbon dioxide (it is easy to
measure carbon dioxide in the air b/c it absorbs infrared radiation really well)
- If we measure how much O2 is consumed or CO2 is produced, we
can make an estimate of how much energy the animal is using
- For O2 consumption, the amount of heat produced from each
macromolecule is almost the same, however for CO2 production, the
amount of heat produced from each molecule differs
- So, we need to make assumptions about what kind of fuel
(macromolecule) the animal is using when trying to determine their
metabolic rate indirectly
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Document Summary

Metabolism (cid:862)the set of processes by which cells and organisms acquire, rearrange, and void commodities in ways that sustai(cid:374) life(cid:863) (cid:862)the su(cid:373) of all (cid:272)he(cid:373)i(cid:272)al rea(cid:272)tio(cid:374)s i(cid:374) a (cid:271)iologi(cid:272)al e(cid:374)tit(cid:455)(cid:863) Metabolism is just what the organisms do with the energy it gets from food - it is just a descriptor of what the organism is doing. We care more about metabolic rate b/c we can use it to describe how an organism does metabolism. Metabolic rate (cid:862)a(cid:374) orga(cid:374)is(cid:373)"s rate of energy consumption; the rate at which it converts chemical-bond energy to heat a(cid:374)d e(cid:454)ter(cid:374)al (cid:449)ork(cid:863) Metabolic rate = energy/time so it can be measured in watts. Metabolism vs metabolic rate a tree has a lot of metabolism but it has a low metabolic rate; taking time into account is important. Bmr homeotherms in their thermoneutral zone means these orga(cid:374)is(cid:373)s are(cid:374)"t spe(cid:374)di(cid:374)g a(cid:374)(cid:455) e(cid:374)erg(cid:455) to (cid:373)ai(cid:374)tai(cid:374) their (cid:271)od(cid:455) temperature so this is when their metabolic rate is measured.

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