1
Q
What is bioenergetics?
A
- the flow of energy within a living system
2
Q
Substances Used in Photosynthesis
A
- chlorophyll, water, CO2, light (sun), which produces glucose and carbohydrates
3
Q
Write out the overall chemical equation for photosynthesis.
A
6H20 + 6CO2 + light –> C6H12O6 + 6O2
4
Q
Name two different energy transfers?
A
- aerobic chemical reactions (require oxygen)
- anaerobic chemical reactions (do not require oxygen)
5
Q
The process by which plants use the sun’s energy to create food
A
- photosynthesis
6
Q
Reactants needed for photosynthesis
A
- CO2
- H2O
- chlorophyll
- light
7
Q
Reactants needed for photosynthesis
A
- glucose (C6H12O6)
- oxygen
8
Q
The process in animals that allows recovery of chemical energy stored in plants
A
cellular respiration
9
Q
What is cellular respiration?
A
- in animals and human allows recovery of the chemical energy stored in plants
10
Q
The source of energy that is transferred to plants via photosynthesis
A
the sun
11
Q
The way in which herbivores, carnivores, and omnivores obtain energy
A
- transfer energy by consuming different foods in aerobic and anaerobic chemical reactions
12
Q
what three main things do humans expend energy on?
A
- physical activity
- basal processes in the body
- digestion and absorption of food) thermic effect of feeding
13
Q
How is energy defined?
A
- the capacity to do work
- is chemically stored in food
- can be converted into mechanical or electrical energy
14
Q
what is the first law of thermodynamics
A
- energy can neither be created or destroyed but instead transforms from one state to another without being used up
15
Q
what forms does biological work take
A
- mechanical work of muscle contraction
- chemical work for synthesizing molecules
- transport work that concentrates diverse substances in body fluids
16
Q
Energy transformation in the human body depends on:
A
- redox reactions
- chemical reactions that conserve and liberate energy in ATP
17
Q
Provide an example of a redox reaction during intense excercise
A
- Pyruvate is reduced (gains 2 electrons) to form lactate
- in recover lactate is oxidized (loosed 2 electrons) to form pyruvate
- this reaction is catalyzed by enzyme called lactate dehydrogenase
18
Q
What is potential energy?
A
- energy associated with a substances structure or position
19
Q
What is kinetic energy?
A
- refers to energy of motion
20
Q
What is the primary function of the chemical potential energy stored in ATP?
A
- it powers all biological work
21
Q
What enzyme is responsible for the degradation of ATP and the release of its energy?
A
- the enzyme responsible is called adenosine triphosphatase
- this provides rapid anaerobic energy supply
22
Q
What process synthesizes ATP by transferring hydrogen and electrons to oxygen?
A
- the electron transport chain
23
Q
Name two high-energy compounds the body uses during short, intense exercise?
A
- ATP
- PCr
24
Q
What is ATP
A
- It is the body’s main source of energy that captures free energy in high-energy phosphate bonds
- it splits rapidly without O2
- the body only stores a really small amount of(80-100g of ATP) therefore there is contiual resynthesis of ATP
- Chemical potential energy in ATP powers all biological work
25
What is PCr
- It is another high-energy phosphate compound
- PCr quickly releases large amounts of energy when bonds between creatine and phosphate are broken, this energy is immediately used to resynthesize ATP from ADP + P
- cells store 4-6x more PCr than ATP
- It is a reservoir for high-energy phosphate bonds, for short-term 8- 10 sec, all out muscular excercise
26
What type of physical activity is fueled by the ATP-PCr system?
short term, explosive, all out muscular activity lasting for 8-10sec
27
Is energy conserved when glucose is burned in a fire?
- no potential energy is dissipated as heat, no energy is conserved
28
How does the body release chemical energy from glucose?
- through a slow, step-wise process called cellular oxidation
29
How does the body overcome the activation energy for these reactions?
- through enzymes and body heat
30
What is the major advantage of cellular oxidation over burning?
energy is conserved within activated molecules (like ATP) instead of being lost as heat
31
What is the main source of energy for ATP phosphorylation?
- oxidation of hydrogen from macronutrients such as CHO, lipids and protein
32
What are the two highly specific co-enzymes that are reduced with hydrogen from macronutrients?
- nicotinamide adenine dinucleotide (NAD+) derived from niacin (vit b3)
- flavin adenine dinucleotide (FAD) derived from riboflavin (vit b2)
33
What are the high-energy molecules that carry hydrogen and their electrons?
- NADH
- FADH2
34
The most efficient way for the body to make ATP is through the
- ETC
- oxidative phosphorylation
35
How does oxidative phosphorylation work
- High energy electron carriers, NADH and FADH2 carry hydrogen atoms and electron to the electron transport chain (ETC)
- as electrons move down the ETC, the liberated energy powers the synthesis of ATP from ADP and inorganic phosphate
- as the final step, hydrogen and and its elctrons combine with oxygen, the final electron acceptor to form water
36
What is the main purpose of oxidative phosphorylation?
- to synthesize ATP
- This process is responsible for creating 90% of bodys ATP
37
What is the respirator chain
- it is the electron transport process, where the mitochondria contains cytochrome carrier molecules on their inner memebrane that remove electrons from hydrogen and pass them to O2
38
What is the theoretical ATP yield from the oxidation of one mole of NADH compared with the actual?
- the theoretical yield is 3 ATP, but ATP needs to be shuttled out of the mitochondria, so it's actual yield is 2.5 ATP per NADH
39
What is the average net ATP yield from the oxidation of one mole of FADH2
- when FADH2 donates a hydrogen this yields 1.5 ATP per hydrogen mol
40
What is the energy conserved by the formation of one mole of ATP?
- 7.3 kcal of energy
41
How many kcal of energy are conserved by the ATP produced from one mole of NADH?
- since 2.5 moles of ATP is produced per mole of NADH so it is 2.5 x 7.3 kcal = 18.25 kcal is conserved as chemical energy
42
What is the relative efficiency of the Electron Transport Chain (ETC) and oxidative phosphorylation in transferring chemical energy?
- 34%
- because 1 mole of of NADH originally had 52 kcal
- therefore 18/52 = 0.346
43
What happens to the remaining energy that is not converted into ATP?
66% is dissipated as heat
44
What are the 3 conditions for ATP resynthesis using energy from macronutrients
1. availabilty of reduced NADH and FADH2 in tissue to carry electrons
2. precense of oxygen to act as the final electron acceptor to combine with hydrogen to form water
3. sufficient mitochondria and enzymes to ensure energy transfer reactions proceed at an appropriate rate.
45
What happens during strenous excercise
- During strenuous exercise, there might not be enough oxygen to keep up with the energy demand. This creates an imbalance where hydrogen atoms are being released from macronutrients faster than oxygen can accept them
- as a result, electrons that flow down the ETC back up, hydrogen atoms accumulate and lactate forms
46
What are the intra skeletal muscle energy sources
- PCr
- ATP
- Glycogen
- carbon skeleons from amino acids
- tryacylglycerols (TAG)
47
What is the primary role of the liver and adipocytes in providing fuel for the muscles?
- The liver provides rich sources of glucose (glycogen), free fatty acids, and amino acids
- The adipocytes store triacylglycerols, which give large amounts of free fatty acids that are released into the blood and carried to skeletal muscle.
48
Where does most of the energy transfer from macronutrients take place within the muscle cell?
Most energy transfer takes place in the mitochondria within skeletal muscle
49
What is the total energy (in kcal) released from the complete breakdown of one mole of glucose?
686 kcal of energy
50
How much energy (in kcal) is required to synthesize one mole of ATP?
7.3 kcal of energy
51
Based on the efficiency and energy yield, how many moles of ATP are produced from the breakdown of one mole of glucose?
- 32 ATP per 1 glucode molecule
- 34% x 686 = 233 kcal of energy
- 233 / 7.3 kcal = 31.918 kcal
52
What are the 2 stages of glucose degradation
1. Glucose is broken down rapidly into two molecules of pyruvate. This process is anaerobic (does not require oxygen)
2. Pyruvate is further broken down into carbin dioxide and water. This reaction take place in the cirtic acid cycle. This process is aerobic (does require oxygen)
53
What are the two main products of glycolysis, and what is the net gain of ATP when the process starts with a glucose molecule?
- 2 pyruvate molecules (enzyme pyruvate dehydrogenase)
- the net gain of ATP is 2
54
What is the main difference between glycolysis and glycogenolysis in terms of ATP investment and net ATP gain?
- glycolysis yields 2 ATP molecules while glycogenolysis begins with a glycogen moleculs, so it by passes the first step, yielding 3 ATP molecules
55
What happens to the hydrogen released during glycolysis?
- the hydrogen released during glycolysis is picked up by NAD+ to form 2 NADH
56
Approximately how much of a glucose molecule's total ATP is produced during glycolysis?
10 -15 %
57
What type of exercise is primarily fueled by the glycolysis pathway?
maximal excercise last 90 seconds
58
How does lactate form?
- during heavy excercise, energy demand exceeds oxygen supply. Therefore the electron transport chain can't process all the NADH being produced by glycolysis.
- therefore the ETC gets backed up and H+ accumulates
- to temporiliy solves this problem, your body combinds excess H+ with pyruvate to form lacate
59
using the excess hydrogen from NADH, which serves two key purposes:
1. freeing NAD+ to accept H+ from glycolysis
2. H+ accumulation slows down the glycolytic rate
60
Provide a step by step break down of the lactate cycle
- lactic acid in skeletal muscle enters venous circulation to heart and dissociates into lactate and hydrogen
- lactate in the hepatic arteries enters liver and is converted in pyruvate and via gluconeogenesis, there is re syntheis of glucose
- glucose is released from the liver into the arterial blood where it is sent back to the skeletal muscle to be used a fuel source
61
How many ATP does gluconeogensis consume
6 ATP
62
What is the Citric Acid Cycle, and what are the key outputs (in terms of molecules and hydrogen atoms) for each pyruvate molecule that enters the cycle?
- the citric acid cycle is the second stage of CHO break down
- it degrades pyruvate into CO2 and water
- 2 pyruvate are conveted into 2 acetyl Co A which then combine with oxaloacetate to form citrate
- this prcess comsumes 3 H2O molecules and one acetate
- per cycle each pyruvate molecule give 3 CO2, 4 pair of hydrogen atoms in NADH and 1 pair of hydrogen atom in FADH2 and 1 GTP which can be quickly converted into ATP
63
describe the 2 phases of aerobic energy metabolism
Phase 1: Citric Acid Cycle
In this phase, the Citric Acid Cycle (CAC) breaks down acetyl-CoA, which is derived from pyruvate. As the cycle turns, it generates a large number of hydrogen atoms (H +, 20 in total). These hydrogen atoms are picked up by coenzyme molecules (NADH and FADH2 ), which act as carriers.
Phase 2: Electron Transport Chain
The second phase is where the energy is actually conserved. The hydrogen-carrying coenzymes deliver their hydrogen atoms and electrons to the Electron Transport Chain (ETC). As the electrons are passed down the chain, they release energy. This liberated energy is then used to synthesize ATP from ADP and inorganic phosphate (P). Finally, the hydrogen ions and electrons combine with oxygen (O ) at the end of the chain to form water (H2O). This process is called oxidative phosphorylation.
64
How does the body use fats for energy? and what is this process called?
- this process is lypolysis
- When the body needs energy, hormone-sensitive lipase is activated
- this stimulates the break down of triacylglycerol (TAG) into glycerols and free fatty acids and releases them into the bloodstream bound to albumin to the muscle fibers
- long chain FFAs enter the cell by either diffusion or with the help of protein transporters to form intracellular TAG
- once in the cell, FFAS are activated by binding to CoA and the is shuttled in by carnitine (the enzyme: carnitine acyl-CoA transferase 1 and 2)
- short and medium chain FFAs diffuse freely in mitochondria
- then inside mitochondria FFAs are broken down into many Acetyl CoA moelcules through beta oxidation.
- then acetyl coA enters CAC and then the ETC to produce large amount of energy
65
HSL's activation is influenced by several factors:
HSL's activation is influenced by several factors:
Stimulated by: Epinephrine, norepinephrine, glucagon, and growth hormone. These are released early during exercise.
Inhibited by: Lactate, insulin, and ketones.
66
Sources of Fat for Catabolism
The body can get fat for energy from three main sources
Circulating TAG in lipoprotein complexes.
Triacylglycerols stored directly in adipocytes (fat cells) and muscle fibers.
Circulating free fatty acids (FFA) bound to the plasma protein albumin.
67
what happens to the hydrogen ions that are released during fatty acid catabolism
- they are oxudized by the respiratory chain to produce ATP
68
Describe the crucial relationship between fat and carbohydrate metabolism.
- The rate of the CAC depends on the concentration of its intermediates, oxalacetate and malate, which are derived from CHOs
- therefore a diet low in CHO can limit fatty acid oxidation due to slow rate of CAC
- "fat burns in a carbohydrate flame"
69
how much is the total ATP for one TAG
around 406
70
Describe the efficiency of converting chemical energy into ATP for fat oxidation vs. glucose oxidation
- 40% is conserved for fat oxidation, while 34% is conserved for glucose oxidation
71
What is the primary role of protein as an energy substrate?
- for endurance activites and heavy training
72
What is deamination, and where does it primarily occur?
- deamination is the romaval of a nitrogen group and this occurs in the liver
73
What is transamination?
- it is when an amino group is passed to another compound
74
What is a carbon skeleton? and where do it go?
- remaining part of the amino acid after transamination and deamination
- it enters the metabolic pathway to produce ATP and the CAC
75
What occurs with excessive prtein intake
- it is converted into body fat
76
Describe the 3 fates of amino acids.
1. Glucogenic Amino Acids: These are amino acids whose carbon skeletons can be used to synthesize glucose via a process called gluconeogenesis. A notable example is the Glucose-Alanine Cycle.
Ketogenic Amino Acids: These amino acids are converted into acetyl-CoA or acetoacetyl-CoA, which can then be used to form ketone bodies or be converted into fat for storage. They cannot be used to form glucose.
Other Amino Acids: Some amino acids can directly enter the Citric Acid Cycle and be oxidized for energy without first being converted into pyruvate or acetyl-CoA.
77
How much energy does alanine-derived glucose account for during prolongued excercise
- 10-15%
78
Describe the the glucose alnine cycle
Alanine Production: During exercise, muscles break down amino acids for energy. The nitrogen from these amino acids (glutamtae) is transferred to pyruvate to form a new amino acid, alanine.
Transport to Liver: Alanine is then released from the muscle into the bloodstream and travels to the liver.
Conversion in Liver: In the liver, the alanine undergoes deamination, where its nitrogen group is removed. The remaining carbon skeleton is converted to pyruvate.
Glucose Synthesis: The liver uses this pyruvate to synthesize new glucose through a process called gluconeogenesis. The nitrogen removed from the alanine is converted into urea and excreted.
Glucose Transport: The newly formed glucose is released from the liver back into the bloodstream and is transported to the muscles to be used for fuel.
The slide notes that during prolonged exercise, this cycle can account for 10-15% of the total exercise energy requirement. After 4 hours of continuous light exercise, alanine-derived glucose can account for a significant portion (45%) of the liver's total glucose release.
79
Categorizes amino acids based on where they enter the metabolic pathway:
Some amino acids, like alanine and cysteine, are converted to pyruvate.
Others, like leucine and lysine, are converted into acetyl-CoA.
Still others, like glutamate and aspartate, enter the Citric Acid Cycle directly as intermediates.
80
What is the NET yield of ATP for lucose alanine cycle and lactate shuttle
- lactate shuttle: gluconenogenesis costs 6 ATP therefore - 26 ATP
- GAC: gluconeogensis cost 6 ATP and 4 ATP to convert nitrogen to urea and excrete it - 22 ATP
BPK 312
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