Week 1: Bioenergetics & Physiology Revision

Question 1

Where is energy supplied from? What is broken down/converted to produce energy (ATP)?

Answer 1

Food supplies energy & the macronutrients are broken down to produce ATP.

Three stage process:
- Eat food –> broken down via catabolism
- Macronutrient oxidation
- Production of ATP

Question 2

What macronutrient is broken down to produce glycogen? What happens to this molecule?

Answer 2

Carbohydrates are broken down into glycogen which is further broken down into glucose.

Glucose undergoes a series of chemical reactions within the muscle to form ATP.

Question 3

What is ATP?

Answer 3

Energy that allows biological work to occur.

Question 4

What happens to ATP to produce energy?

What does the energy produced by ATP allow to occur?

Is ATP a high or low energy compound for storing and conserving energy?

Answer 4

Phosphate bond is broken off. This energy allows actin/myosin coupling to occur.

ATP is a high energy compound for storing and conserving energy.

Question 5

What is the chemical structure of ATP?

Answer 5

Three phosphate molecule and an adenosine molecule.

Note: adenosine = adenine & ribose).

Question 6

What is oxidative metabolism?

ATP allows cross-bridging to occur with the actin-myosin - what happens in this process?

Answer 6

• Carbohydrates, fats and amino acids undergo a series of biochemical reactions
• Carbohydrates can undergo glycolysis to form ATP
• ## Stored phosphocreatine within our muscle which allows to re-buffer ADP back to ATP to continually recycle ATP as well
  1. The myosin head is attached in the muscle when we get a nerve impulse into the muscle centrally from the brain we then release calcium from the sarcoplasmic reticulum that calcium then moves at the myosin binding site for ATP to occur

2. When the ATP is broken down into ADP energy is provided and the actin-myosin head slide to produce movement

Question 7

What enzyme facilitates phosphocreatine replenishing ADP to ATP?

Answer 7

Creatine Kinase

Question 8

What energy source is used at rest?

Answer 8

Carbohydrates & fats

Question 9

Predominant energy source for mid and intense exercise?

Answer 9

The body relies mostly on carbohydrate for fuel - its quicker to break down carbs (less chemical reactions required compared to fat). At lower intensity exercise we can contribute more fat to overall energy consumption because the demand for ATP supply is not as fast.

Question 10

True or False? Protein provides little energy for cellular activity, but serves as building blocks for the body’s tissues

Answer 10

True

Question 11

What are the sugars that form carbohydrate molecules?

Answer 11

Monosaccharides (glucose), oligosaccharides (sucrose, lactose & maltose) and polysaccharides (large chains)

Question 12

What happens once carbohydrates are eaten?

Answer 12

Carbohydrates eaten –> blood glucose –> stored in muscles or liver as glycogen (glycogenesis)

Question 13

What is the difference between glycogen being stored in the muscle or liver?

Answer 13

Muscles
* Glycogen broken down aerobically or anaerobically (glycolysis)

Liver:
* Glycogen –> glucose –> blood –> muscles (glycogenolysis)
* Longer process because it has to be broken down to glucose

Question 14

What exercise does fat supply energy for?

Answer 14

Provides substantial energy during prolonged, low-intensity activity

Question 15

Are body stores of fat larger or smaller than carbohydrate reserves?

Answer 15

Larger

Question 16

What happens to fat when it is eaten?

Answer 16

• Broken down to fatty free acids and glycerol
• They can either be used immediately as energy or stored in the body as fat
• Any excess energy is stored as fat (non-essential fat can be a problem for health and performance)
• Free fatty acids and glycerol (lipolysis) –> that stored fat can then get broken down back into free fatty acids and glycerol via a process known as lipolysis.

Question 17

Fat has about …. the store of energy compared to carbohydrates

Answer 17

50x

Question 18

For a 65kg person who is ~12% body fat, they would have how many grams of glycogen in the liver, muscle glycogen, glucose in body fluids?

Answer 18

110g of glycogen
250g of muscle glycogen
15g of glucose in body fluids

(6500kJ of energy)

Question 19

For a 65kg person who is approximately 12% fat they would have how many grams of subcutaneous fat and intramuscular fat?

Answer 19

7800g of subcutaneous
161g intramuscular

(302,820kJ of energy)

You can see the store of energy of fat in the body is much greater than carbohydrates. The issue is accessing it during exercise which is difficult

Question 20

Energy content of fat vs carbohydrate (per gram)?

Answer 20

1g of carbohydrate = 17kJ (16.8)
1g of fat = 37kJ (37.8)

less energy in carbohydrate as there are less carbons

Question 21

How is protein used?

Answer 21

Can be used as energy but contributes very little. When we eat protein (beef, chicken etc) that will be broken down to amino acids. Used for growth and repair

Question 22

If protein is used for energy how must it be used?

Answer 22

When protein is used for energy production it must be converted to fat (lipogenesis) or glucose (gluconeogenesis) in the liver

Otherwise it is excreted as urea

Question 23

True or False - We can generate FFA’s in times of starvation through lipogenesis

Answer 23

True

Question 24

What are the three main energy systems?

Answer 24

ATP-PCr system (phosphagen system) : anaerobic

Glycolytic system: Anaerobic

Oxidative system: Aerobic

Question 25

ATP-PCr system One molecule of ATP is produced per ..... of phosphocreatine ATP-PCr provides an ..... source of energy during very ..... exercise It depletes really quickly - T or F? How long does it last? We can maintain ATP levels for about .... seconds before they start to drop off

Answer 25

1. One mole 2. Immediate, intense 3. True 4. 3-20 seconds 5. 10 secons

Question 26

Glycogen breakdown may be anaerobic or aerobic - T or F

Answer 26

True

Question 27

Glycogen breakdown & synthesis Breakdown of glucose (.... ATP) or glycogen (.... ATP) in absence of oxygen to lactic acid Occurs within the ..... Is relatively .... When there is no oxygen present that glucose gets broken down to produce..... The lactate itself becomes a fuel. Lactic acid produces ... That hydrogen is what drops the .... of the muscle and causes ..... That acidosis can inhibit the ..... enzymes or the enzymes that fuel ..... It can also inhibit actin-myosin coupling through blocking ..... binding sites in the muscle

Answer 27

1. 2 ATP, 3 ATP 2. Cytoplasm 3. Fast 4. Lactate and 2 hydrogen ions 5. 2H+ 6. pH of the muscle, acidosis 7. Glycolytic, glycolysis 8. Calcium

Question 28

What is a rate limiting step of glycolysis?

Answer 28

Phosphofructokinase

Question 29

The glycolytic energy system Requires ..... enzymatic reactions to breakdown glucose and glycogen into ATP The pyruvic acid produced by anaerobic glycolysis becomes ..... (lactate + H) One mole of glycogen produces .... mWole of ATP & one mole of glucose produces .... moles of ATP Therefore more energy is produced from ...... than from ...... But glycogenolysis and glycolysis have the negative effects as a result of ..... being created and then in the absence of oxygen lactic acid and that causes lactate and hydrogen ions (these consequences are discussed in the previous section)

Answer 29

- 12 - lactic acid - 3, 2 - Glycogenolysis than from glycolysis - Pyruvic acid

Question 30

What are the three phases of glycolysis?

Answer 30

Phase 1: Sugar activation * Glucose molecule is primed by using 2 ATP to prime that to form fructose-1,6 bisphosphate * There are two phosphates at the end of that glucose molecule Phase 2: Sugar cleavage * In this phase that 6 carbon chain is broken into 2 carbon chains and that gets primed for the main oxidation and formation of ATP in the next phase of glycolysis Phase 3: Sugar oxidation and formation of ATP * The three carbon chain with a phosphate produces 4 ATP (previously 4 ADP) and two hydrogen ions which get picked up by NAD (a coenzyme) and takes them off to the electron transport chain * The end result is 2 pyruvic acid molecules and when oxygen is present it is then sent via the Kreb cycle to the aerobic pathway * When there is no oxygen present that pyruvic acid is converted into lactate acid (2 lactate & 2 hydrogen ions)

Question 31

What is involved in the oxidative production of ATP?

Answer 31

* Involves three processes: - Glycolysis (oxidative) --> glucose/glycogen is broken down into pyruvate. When 02 is present that pyruvic acid enters mitochondria and is converted to acetyl-COA. - Krebs cycle --> three carbon chain of pyruvate is converted into 2 acetyl-CoA molecules and they enter the kreb cycle where they are used to produce hydrogen ions which are sent to the electron transport chain via NAD & FAD. The H+ combine with two carriers: - 1) Nicotinamide adenine nucleotide (NAD) - 2) Flavin adenine nucleotide (FAD) - Electron transport chain

Question 32

Where is oxidative capacity produced? It it slow and what quantity is produced in terms of energy yield?

Answer 32

The mitochondria Slow rate but high energy yield

Question 33

Process of oxidation of carbohydrate?

Answer 33

* Pyruvic acid from glycolysis is converted to acetyl coenzyme A (acetyl CoA) * Acetyl CoA enters the Krebs cycle and forms 2 ATP, C02 and H+ * H+ in the cell combines with two coenzymes (NAD & FAD) that carry it to the electron transport chain * Electron transport chain recombines H+ to produce ATP and water * One molecule of glycogen can generate up to 39 molecules of ATP

Question 34

Total of ATP produced in aerobic glycolysis & ETC?

Answer 34

Glycolysis: 3 ATP, 2 ATP through kreb cycle, 34 ATP through electron transport chain = 39 ATP molecules from 1 mole of carbohydrate glycogen.

Question 35

Oxidation of fat

Answer 35

* Triglycerides stored in muscle and fat cells * These triglycerides are broken down by lipases to 1 glycerol and 3 free fatty acids which attach to plasma albumin and can diffuse into muscle. * Beta oxidation is the process of breaking down FFA to acetyl CoA * Acetyl CoA enters the Krebs cycle and the electron transport chain * Oxidation of fat within the Krebs cycle requires carbon chains from carbohydrate since one of the substrates that acetyl CoA combines with oxaloacetic acid and is derived from pyruvic acid (CHO source only) Beta oxidation is fundamentally breaking down big long carbon chains into smaller carbon chains and ultimately into acetyl-CoA which is two carbon fragments and they enter the kreb cycle. * Fat needs more oxygen per gram than CHO since FFA contain more carbons and hydrogens - Palmetic acid: C16H3202 --> this has 16 carbons and 32 hydrogen - Glucose: C6H1206 * ATP production for each gram of: - Fat (~9kcal or ~37.8kj) - CHO (~4kcal or ~16.8kJ) * Per molecule of oxygen - Fat gives 5.6 ATP - CHO gives 6.3 ATP (more energy for same 02 compared to a fat)

Question 36

What percentage of protein is used during rest and exercise?

Answer 36

Less than 5-10%

Question 37

What is the alanine glucose cycle (cahill cycle)?

Answer 37

The Alanine-Glucose cycle or the Cahill cycle - the process which involves muslce protein being degraded to provide more glucose and it generates more ATP for muscle contraction. A series of biochemical reactions whereby Alanine is converted to muslce glucose in the liver. During prolonged exercise the branch chain of amino acids are released from the muscles and they are carbon back bones they are used as an energy source while the nitrogen component to the amino acid is made to produce alanine. The alanine is then converted to glucose in the liver helping the body maintain its glucose levels.

Question 38

Why is protein oxidation complex?

Answer 38

Because amino acids contain nitrogen which cannot be oxidised Amino acids: * Gluconeogenesis in liver * Enters Kreb Cycle as pyruvate * Enters as acetyl CoA * Some also broken down to ammonia and excreted as urea

Question 39

What percentage of the energy expended by the human body is degraded to heart; the rest is used for cellular and muscular activity

Answer 39

60-70%