Chapter 3 - ATP-PCr Metabolism

Energy

required to move/work (determines exercise capacity)

Plants Use Sunlight to

drive chemical reactions → forms carbs, fats, proteins

Humans Consume the Plants

to obtain energy → convert one form of energy into another

Energy Is A

dynamic state

• mechanical work

• chemical or eletrical work

Metabolism

sum of all chemical reactions in the body

Catabolism

breakdown of molecules

Anabolism

synthesis of molecules

Bioenergetics

converting food/nutrients into useable energy

• the body can use carbs, fats, proteins

What Factors Drive Metabolism

type of exericse, diet, ATP, hormones

Parts of a Cell

• cell membrane → protects inside of cell from ECF

• nucleus → contains cells genetic material

• cytoplasm → fluid portion of cell

Cellular Chemical Reactions

endergonic, exergonic, coupled reactions

Endergonic Reactions

requires energy to be added for the reaction to occur

Exergonic Reactions

release energy as a result of a chemical reaction

Coupled Reactions

free energy from one reactions is used to drive the second reaction

Oxidation-Reduction Reactions

oxidation: removal of an electron

reduction: addition of an electron

ATP

• immediate energy source for muscular contraction

• universal energy donor

• primary energy carrying-molecule

ATP is Made of

adenosine + 3 phosphates

ADP is Made of

adenosine + 2 phosphates

Structure of ATP

adenine + ribose + 3 phosphate groups

Adenosine

ribose + adenine

ATPase

enzyme that breaks ATP down

• ATP → ADP + Pi + energy)

Rate of ATP Depends On

force of contraction

Normal ATP Storage

80-100 g

Why Not Just Store ATP?

• it is chemically unstable

• it is to heavy for efficient long-term storage

Enzymes

regulates the speed of cellular chemical reactions

Enzymes Lower

activation energy → faster reactions

In Metabolism Enzymes

regulate the catabolism of chemical compounds to produce energy

Activity of an Enzyme is Measured By

the rate at which it forms the enzyme-substrate complex

Modulators

subtsnaces that increase or decrease enzyme activity

Enzyme-Substrate Complex

formed when a substrate binds to the active site of an enzyme

Shape of an Enzyme’s Active Site is

specific to the shape of a substrate, allowing formation of the complex

Factors Affecting Enzyme Activity

• cofactor (non-protein component - organic coenzyme)

• substrate concentration (amount and availability)

• modulator (stimulator or inhibitor)

• temperature

• pH

• enzyme

Temperature Affect on Enzyme Activity

• increase in temperature can increase enzyme actiivty

• large increases in temperature decrease enzyme activity

pH Affect on Enzyme Activity

if pH moves away from optimal range → enzyme activty decreases

Enzymes Under Complex Control

1. competative inhibition - fighting for binding sites

2. non-competative inhibition - something is getting in the way

3. feedback inhibitions - products of reactions, inihibt reactions

4. enzyme affinity - how likely enzyme is to catalyze the reaction

Classification of Key Enzymes

almost all enzyme names end in -ase

Kinase

transfer a phosphate group (phosphorylation)

Phosphorylase

addition of a Pi molecule

Phosphatase

remove phosphate group

Dehydrogenase

remove H+ atoms

Oxidase

catalyze oxidation-reduction reactions involving O2

Isomerase

rearrangement of the structure of molecules

Main Nutrients

carbohydrates, lipids, proteins

Carbohydrates

• glucose

• glycogen

• muscle & liver → where glycogen is stored

How to Get From Glycogen to Glucose

glycogen → glycogenolysis → glucose

Lipids

• fatty acids → used for muscle energy

• triglycerides → stored in fat cells

• steroids - cholesterol

Ratio of Carbon to Oxygen

is greater in fats than carbs

Proteins

amino acids → contribute to energy-providing pathways in muscle

Nutrient Reliance Depends On

exercsie intensity

Training Tries To

increase lipid use and reserve CHO

Primary Factors Affecting Energy Production

1. total energy demand (high in marathon, low in 100m)

2. rate of demand (high in 100m, low in marathon)

Phosphagen System

for very breif, explosive events

Anaerobic System

for high-intensity, short-duration exercise

Aerobic System

for low-moderate intensity, longer duration exercise

Money Analogy

• ATP-PCr (change) - fastest way

• Glycolysis (wallet) - have it, spends ATP then makes more

• oxidative (bank) - takes time to get there

Energy is Like Money

glycogen → chequing

fat - savings

Anaerobic (ATP-PCr)

fastest and simple way to make ATP (immediate energy)

• short duration

• does not require O2

Anaerobic System Uses

phosphocreatine to regenerate ATP

Phosphocreatine (PCr) System Reaction

PC + ADP → ATP + creatine

Enzyme Responsible - Phosphocreatine

creatine kinase

Anaerobic System Used

• at beginning of exercise

• during short-term, high intensity exercise

Phosphocreatine

1 ATP per unit of “substrate”

• rapid, close, limited

ATP vs PCr

• concentration of PCr is only 4-5x that of ATP

• provides energy at a high rate; low capacity

• we must produce all the ATP we need

Adenylate Kinase

catalyzes the conversion of the various adenosine phosphates (ATP, ADP and AMP)