LIFESCI 23L Lecture Notes - Lecture 4: Ectotherm, Activation Energy, Poikilotherm
Lecture D: Metabolism in Goldfish
OVERVIEW OF SKILLS/CONCEPTS
● Handling goldfish to formulate predictions about metabolic rates and coming up with ways to test them
● Concepts: designing experiments, proposing testable hypotheses, t-test and p-values
● Skills: handling of live specimen, using computer interface w/ oxygen collection data, and analyzing
data
●
BACKGROUND
● METABOLISM: totally of chemical reactions occuring in living organisms in a given instant
○ Catabolic reactions: break down nutrient molecules, release energy, create ATP
○ Anabolic reactions: synthesize molecules, use up ATP
○ Exergonic vs. endergonic reactions
■ Exergonic reactions even need to be pushed passed barrier (activation energy)
● How to surpass activation energy?
○ Heating up system not great in living systems → ENZYMES!
■ Enzymes catalyze reactions, but when enzymes run out (are all
occupied) speed levels off as there are more substrates than
enzymes
■ No enzyme: rxn rate increases steadily as substrate levels
increase
● pH, temp affects enzyme activity; many have an optimal pH and temp at which they work
● Some organisms can produce different versions of the same protein under different conditions
● Enzymes can
○ Be expressed in different isoforms
○ At different times switched on off
○ Interact w/ other molecules/enzymes to change (increase or decrease) their activity
○ Animals use these properties of enzymes to adapt to their environments
● Temp and living systems
○ Homeotherm (endotherm): an organism, such as a mammal or bird, having a body temp that is
constant and largely independent of surrounding temp → generates own heat
■ Can regulate internal temp by producing heat metabolically or using active mechanisms
of heat loss; body temp stays constant over wide interval of external temps; metabolic
rate high for low/hot temps, low at (middle) thermoneutral zone
○ Poikilotherm (ectotherm): an organism, such as fish or reptile, having a body temp that varies w/
the temp of its surroundings; receives heat from environment;
■ External heat sources; metabolic rate proportional to environmental temp;
■ Can regulate body temp with BEHAVIOR
○ Metabolic rates in different mammals
■ Body mass increases, total metabolic rate increases
● Amount of heat produced proportional to # of cells, but rate of heat loss is
proportional to (surface) area → more heat retained in bigger animals
● Mammal size vs. heart rate? Larger animals → slower resting heart rate
■ Smaller animals have a larger metabolic rate than large animals
● Metabolism in fish
○ Ectotherm: metabolism easily manipulated by changes in temp
○ Factors that affect fish metabolism
find more resources at oneclass.com
find more resources at oneclass.com
Document Summary
Handling goldfish to formulate predictions about metabolic rates and coming up with ways to test them. Concepts: designing experiments, proposing testable hypotheses, t-test and p-values. Skills: handling of live specimen, using computer interface w/ oxygen collection data, and analyzing data. Metabolism: totally of chemical reactions occuring in living organisms in a given instant. Catabolic reactions: break down nutrient molecules, release energy, create atp. Anabolic reactions: synthesize molecules, use up atp. Exergonic reactions even need to be pushed passed barrier (activation energy) Heating up system not great in living systems enzymes! Enzymes catalyze reactions, but when enzymes run out (are all occupied) speed levels off as there are more substrates than enzymes. No enzyme: rxn rate increases steadily as substrate levels increase. Ph, temp affects enzyme activity; many have an optimal ph and temp at which they work. Some organisms can produce different versions of the same protein under different conditions.
