Module 6 - Energy Metabolism Part 1 Flashcards
What is energy metabolism
It is reactions where the body obtains and expands energy from food
What are coupled reactions
Reactions that require energy in order to produce energy
What kinds of energy are used in the body
B) what are the main fuels that cells use for energy production
Energy: heat (body temp), mechanical (muscles), electrical (nerves) and chemical (digestion)
Fuels: glucose, fatty acids, amino acids
Where do the citric acid cycle and electron transport chain take place in the mitochondrion
Citric acid cycle: inner compartment
Electron transport chain: inner membrane
Process of fats being stored as fats
Chilomicrons and VLDL loaded with TG. Then, lipoprotein lipase hydrolyses TG, releasing FA to enter adipose cells. There they are reassembled into TG in adipose tissue
How to use fat for energy. What percentage of energy comes from fats
Hormone sensitive lipase release FA and glycerol.
60% of the body’s energy needs at rest
Anabolism versus catabolism
Anabolism: uses energy to build compound
Catabolism: breaks compounds and releases energy
What percentage of energy comes from proteins
10% of energy. Amino acids can also be transformed and stored as fat
what is gluconeogenesis
Making glucose from non-carbohydrate sources such as amino acids or glycerol. In fact, in the absence of glucose, body proteins lose their nitrogen’s and are broken down to make glucose
What is ATP
High energy compound that powers all activities in living cells. Bonds of phosphate groups contain a lot of energy and when they are broken, energy is released
When the body converts food energy to be used by cells, how much energy is lost to heat
Half the energy is lost as heat
What is the Thermic effect of food?
How much energy does this represent for a diet
It’s the energy required for digestion, absorption and disposal of ingested nutrients
- 10% of energy for a mixed diet
Can fatty acids be converted into pyruvate?
No they can also be converted into acetyl-CoA. Glycerol can be converted to pyruvate though
What is pyruvate. Can it make glucose?
A 3-Carbon compound that plays a key role in energy metabolism
Pyruvate can also be used to make glucose
What is acetyl CoA. Can it be used to make glucose?
A 2 Carbon compound to which a molecule of CoA is attached (made from B vitamin pantothenic acid)
Cannot be used to make glucose
What is the TCA cycle
A series of metabolic reactions that breaks down molecules of acetyl CoA to CO2 and H
Which complexes help metabolic reactions happen
Enzymes (remain unchanged) and coenzymes (required for enzymes to function, b vitamins are great coenzymes)
Goal of electron transport chain
Transports electrons from hydrogen to oxygen, captures about half the energy released by breaking C-C bonds and storing it in high energy bonds of ATP.
Is glucose to pyruvate a reversible reaction
Yes. It can be converted back to glucose with the help of the liver
What is the goal of glycolysis
Splitting glucose for energy. Yields two 3 carbon molecules which get converted to pyruvate
What are the differences between the aerobic and anaerobic pathways of pyruvate once it’s formed
Anaerobic: quick energy needs. Pyruvate is converted to lactate without oxygen for short duration of high- intensity exercise and energy needs
Aerobic: slower energy needs. Pyruvate is converted to acetyl CoA
Under what circumstances would pyruvate to lactate happen
In absence of sufficient oxygen in the mitochondria, pyruvate can accept hydrogens which will turn it to lactic acid. This produces ATP quickly anaerobically for short durations
What is the cori cycle
When lactate from muscles is reconverted to glucose in the liver
Explain the pyruvate to Acetyl CoA system
It is slower, longer and uses oxygen, pyruvate enters the mitochondria and carbons are removed producing CO2 and then the 2 carbon compound joins CO2 to form acetyl CoA which is irreversible
Pyruvate can be used to make which compounds (directly)
Glucose, acetyl CoA, lactate and amino acids
Which amino acids (ketogenic and glucogenic) are used to make pyruvate vs acetyl CoA
Ketogenic can be used to make acetyl CoA (therefore can’t make glucose) and glucogenic can make pyruvate (and therefore glucose)
Glycerol can be used to make which compounds (2)
Glucose and pyruvate
What is the process of fatty acid oxydation
Fatty acids are taken apart 2 carbon fragments at a time and then they form acetyl CoA. As this occurs, hydrogens and electrons are released and carried to the electron transport chain
How to fatty acids lose their carbons to become acetyl CoA
A fatty acid is first activated by CoA. As each carbon-carbon bond is broken, hydrogens and electrons are released and picked up by coenzymes. Then another CoA joins the chain and the beta carbon weakens and acetyl CoA slips off leaving a fatty acid that is two carbons shorter
What is the first step for amino acid coming into energy metabolism
They must be deaminated
What are the entry points of amino acids to energy pathways
It can be converted to pyruvate (glucogenic), or converted to acetyl CoA (ketogenic) or it can enter the TCA cycle directly (glucogenic)
What is an example of an amino acid that is both ketogenic and glucogenic
Tryptophan
What is the starting molecule of the TCA cycle
Oxaloacetate
Which molecule does not yield both glucose and amino acids
Fatty acids
Which macromolecule provides the most energy per gram
Fat because it has the most carbon hydrogen bonds
