Bioenergetics
The study of how organisms manage their energy resources.
Metabolism
all of the chemical reactions in the body
In humans how is energy expressed?
1kcal (which equals 1000 cal)= 1 calorie (dietary)
Myofibrils also use some of the energy released in our bodies to cause....?
the sliding of the actin and myosin filaments
Energy is released...?
when a chemical bonds are broken
energy substrates are mainly composed of?
Carbon, hydrogen, and oxygen; but in the case of proteins also nitrogen
at rest the energy that the body needs is derived from?
almost equally from the breakdown of carbs and fats
during intense, short duration muscular effort, what is used?
carbs with less reliance on fat to generate atp
during longer, less intense exercise utilizes what?
carbs and fat for sustained energy production
all carbs are ultimately converted to what?
glucose
during resting condition: where are ingested carbs started?
in the muscles and they live as glycogen
where is the glycogen stored?
in the cytoplasm of muscle cells until those cells use it to form ATP; in the liver is converted back to glucose as needed and then transported by the blood to active tissues where it is metabolized
What is the only energy sourced utilized by the brain tissue
carbs
what type of energy proves a large portion of long duration and less intense exercise
fats
can be used as a minor energy source under some circumstances but has to be converted to glucose first
protein
gluconeogenesis
the process of converting protein or fat into glucose
lipogenesis
the process of converting protein into fatty acids
how much (in a percentage) can protein supply of the energy needed to sustain prolonger exercise
about 5-10%
what is the most basic units of proteins?
amino acids
a gram of protein yields about how many kcals?
4.1 kcal
the most calorie dense substrate is?
a) carbs b) protein c) fat
c) fat
fat can be catabolized through which of the following pathway(s):
a) ATP/PCr b) glycolysis c) oxidative d) all of the above
c) oxidative
B-oxidative converts a free-fatty acid into:
a) Acetyl CoA b) glucose c) glycogen d) pyruvate
a) acetyl CoA
Both carbs and fat contain these elements:
a) C b) H c) N d) all e) A and B
e) A and B
glycolysis occurs in the:
cytoplasm
an enzyme initiates a catabolic reaction:
true or false
false
what hormone allows glucose uptake into a cell
insulin
the highest atp yield occurs during
Oxidizing FFAs which creates a 100+ ATP
PFK a rate limiting enzyme, decreases the rate of glycolysis when there is a large amount of ______ in this system
ATP
How do you create ATP?
ADP, Pi and energy
During the ATP PCr system what happens?
PCr + Creatine Kinase > Cr + Pi + Energy
PCr is Phosphocreatine and it recycles ATP from ADP.
Also, PCr takes around 3-5 minutes to regenerate.
What is the rate limiting enzyme of ATP PCr System?
When ATP Levels decrease, Creatine Kinase will generate more ATP.
Also, When ADP Levels increase, Creatine Kinase increases.
What is the PCr ATP yield?
1 PCr generates 1 ATP
What does Creatine Supplementation allow you to do?
It allows you to do more short term intense activities because your body has more Creatine Phosphate.
Where is creatine phosphate found? (not in the body)
In red meat. So, normally vegans have low levels of creatine phosphate.
After you have a hard workouot, What is elevated?
CK (Creatine Kinase)
What is the rate limiting enzyme of glycolysis?
Phosphofructokinase (PFK). As ATP levels decrease, PFK activity increases.
Similar to CK
The Glycolytic System.
-2 net ATP with Glucose and 3 net ATP with glycogen
-It lasts for 15 seconds - 2 minutes.
-Glucose or Glycogen must be broken down into Glucose-6-phosphate and ends with Pyruvate or Pyruvic acid
Where do we get the glucose from for glycolysis?
From the blood.
If we deplete that, then we break down glycogen from the liver.
What if Glycolysis does not have oxygen present?
pyruvate is converted into lactic acid.
-Lactic acid impairs muscle contraction
The Oxidative System
The body's most complex energy system
ATP Yield: 1 glucose > 32 or 33 Net ATP
1 FFA > 100+ ATP because FFA creates a ton of Acetyl CoA
3 Stages: Glycolysis, Kreb's Cycle, and ETC
What are the products of kreb's cycle
2 ATP, 8 NADH, and 2 FADH per 2 Krebs cycles.
What is the Kreb's Cycle and ETC rate limiting enzyme? How does it work?
Isocitrate dehydrogenase. It works similar to CK and PFK. (inhibited by ATP, activated by ADP)
What does ATP synthase do?
Creates ATP by pumping hydrogen from inside the mitochondria and that connects ADP+Pi=ATP.
Travel from high concentration>low concentration
Which one produces more ATP: NADH or FADH? WHY?
NADH: 2.5 ATP
FADH: 1.5 ATP
NADH is higher because it enters the ETC first and contributes more to it.
What is the total number of NADH, FADH, and ATP
NADH-10*2.5=25
FADH-2*1.5=3
ATP-4=4
Overall 32 net ATP per 1 glucose molecule.
(33 net ATP per glycogen molecule due to 5 ATP being produced instead of 4).
How do we store fats in our body?
In the form of Triglycerides.
Why do fatty acids generate more ATP? Why is it a slower process?
Fatty Acids generate more ATP because there is 16 Carbon FFA that yield 8 acetyl CoA compared to glucose yielding 2 acetyl CoA.
It is much slower because the Carbon Chains take a long time to be reduced.
Define Beta oxidation
the process of converting FFAs to Acetyl CoA.
Since this process directly enters the kreb's cycle Beta Oxidation loses out on 1 NADH molecule.
Net Products for Kreb's Cycle from Beta Oxidation?
3 NADH and 1 FADH per cycle compared to 4 NADH from glucose.
How much ATP does a 16 carbon FFA yield?
106 ATP.
-Beta oxidation (occurs 7 times): generates 28 ATP
-Kreb's Cycle (occurs 8 times): generates 72 ATP
When is protein converted into Glucose to be used for energy?
This is rare and usually only when going through starvation.
What is the energy yield of a Protein?
Hard to determine due to nitrogen.
What are the 3 ways lactate can be an important fuel during exercise?
1. Lactate is taken up by the mitochondria and oxidized
2. Lactate can be transported to another cell to be oxidized.
3. MOST IMPORTANT: Lactate can recirculate back to the liver to be reconverted to glucose.
What are some facts about Type 1 Fiber Types?
They have more mitochondria, more oxidative enzymes, and a greater oxidative capacity
What are some benefits of Endurance training for Type II Fibers?
Type II fibers gain more oxidative capacity, develop more mitochondria, and more oxidative enzymes per mitochondria.
As exercise intensity increases
ATP Demand increases, O2 intake at lungs increase, and O2 delivery by heart and vessels increase.
What are a couple of factors that determine the oxidative capacity of muscles?
-Enzyme Activity
-Fiber Type Composition (Type IIx > Type II > Type I) (NEVER THE REVERSE)
- You get more efficient at using your oxygen if participate in Aerobic Training.
What are Succinate Dehydrogenase (SD) and Citrate Synthase (CS)?
-They are both newly found enzymes that are found if you train aerobically.
- CS breaks down Acetyl CoA
The more enzymes you have, _____
The more ATP you can produce faster