Lecture 6 - Bioenergetics 1 Flashcards
what are substrates and list the diferent types
fuel sources from which we make energy (ATP)
- > these are comprised of three groups
1. carbohydrates
2. Fats
3. proteins
bioenergetics
the conversion of substrates into energy
- > this process occurs at the cellular level
metabolism
the chemical processes that happen in the body to convert food to energy
1 calorie (cal)
is the heat energy required to raise 1g of water from 14.5 to 15.5
cal vs kcal vs Calorie
1000 cal = 1 kcal = 1 Calorie
substrates are made up of which 4 elements
- > carbon
- > hydrogen
- > oxygen
- > nitrogen (only in proteins)
where is energy from chemical bonds in food stored?
in a high energy compound called ATP
when are substrates consumed
Resting
- > 50% carbs 50% fats
Exercise (short term)
- > more carbs
Exercise (long)
- > carbs and fats, proteins only consumed for energy in dire situations
characteristics of carbs
all carbs are converted to glucose
- > 4.1 kcal/g (2500 kcal stored in body)
- > extra glucose is stored as glycogen in the liver and muscles
- > glycogen converted to glucose when needed to make ATP
characteristics of fat
- > very efficient substrate with efficient storage capabilities
- > 9.4 kcal/g (70000+ kcal stored in bogy)
where are carbs and fats stored
*know general trends*
characteristics of protein
- > used as substrate only during starvation (converted into glucose)
- > 4.1 kcal/g
- > converted into Free Fatty Acids through lipogenesis which is used for energy storage and cellular energy
how are fats, carbs and proteins used for energy production
what controls the rate of energy production
substrate availability
- > more available substrate yields higher pathway activity; this is known as the Mass Action Effect
enzyme activity
- > enzymes act as chemical catalysts in specific steps of metabolism (they do not start chemical reactions, they lower the activation energy of a reaction, see picture)
how do enzymes change the activation energy
- > specific enzymes are required for each step of the biochemical pathway
- > more enzyme activity = more product
rate limiting enzymes
- > slows the overall reaction, prevents runaway reaction
- > limits available enzymes required to start one of the early steps in the biochemical pathway
ATP breakdown formula
ATP + water +ATPase = ADP + Pi + energy
- > can occur with or without oxigen
- > reversed by phosphorylation
how much ATP does your body store and why
its stored in small amounts (until needed)
- > it’s stored in small amounts because it is a very large and bulky molecule, inefficient to store it all at one
characteristics of ATP-PCr systems
- > anaerobic, substrate level metabolism
- > ATP yield: 1 mol ATP/1 mol Phosphocreatine
- > lasts 3-15sec
PCr + creatine kinASE - > Creatine + Pi + energy
how is the ATP-PCr system regulated/controlled?
phosphcreatine breakdown is catalyzed by an enzyme called creatine kinase (CK)
- > CK controls the rate of ATP production via a negative feedback systme (when ATP drops, CK levels goes up to fix it, and vice versa)
characteristics of the glycolytic/lactic acid system
- > anaerobic
- > yields 2-3 mol ATP / 1 mol substrate
*2ATP for glucose, 3 for glycogen
- > lasts 15s - 2mins
- > breakdown of glucose/glycogen via glycolysis
- > 10-12 enzymatic reaction (glucose-6-pi and ends with pyruvate)
characteristics of the oxidative system
- > aerobic
- > ATP yield is dependant on substrate
- 32-33 ATP/ 1 glucose
- 100+ ATP / 1 FFA
- > duration: steady for hours
- > unlike other, occurs in mitochondria not cytoplasm
