Chapter 3 Bioenergetics (Pt. 1)

Metabolism

Sum of all chemical rxns that occur in the body

Two categories of chemical rxns that make up metabolism

Anabolic

Catabolic

Anabolic rxns

synthesis of molecules

Catabolic rxns

breakdown of molecules

Bioenergetics

processing of converting foodstuffs (fats/proteins/carbs) into useable energy (ATP) for cell work

Cell structure

Cell membrane (sarcolemma in skeletal muscle)

Nucleus

Cytoplasm (sarcoplasm in muscle) and enzymes

Cell membrane

sarcolemma in skeletal muscle

semipermeable membrane that separates cell from extracellular environment

Nucleus

Contains genes that regulate protein synthesis

Cytoplasm

Sarcoplasm in muscle

fluid portion of cell

contains organelles and enzymes (mitochondria)

Subsarcolemma mitochondria

produce cellular energy needed to maintain active transport of ions (e.g. sodium) across the sarcolemma

Intermyofibrillar mitochondria

provides energy needed to sustain muscle contraction

Subsarcolemma and intermyofibular mitochondria

form a network to provide all regions of the muscle fiber with a constant supply of energy

Molecular biology

Study of molecular structures and events underlying biological processes

Relationship between genes and cellular characteristics they control

Genes

Code for specific cellular proteins

Exercise training and protein synthesis

Strength training results in increases synthesis of muscle contractile protein

Protein synthesis

cellular signals regulate protein syntehsis by turning on or turning off specific genes

Endergonic rxns

Require energy to be added to the reactants

rxtnts + energy —> pr

Exergonic rxns

Release energy: trapped within chemical bonds of molecules

rxtnts—> products + energy

Coupled rxns

Liberation of energy in an exergonic rxn drives an endergonic rxn

Ox-Red rxns

Oxidation: removing an electron

Reduction: addition of an electron

Always coupled.

Hydrogen atoms contain one electron so a molecule that loses a H also loses an e- therefore is oxidized.

NAD and FAD

carrier molecules during bioenergetic rxns

Enzymes

cellular proteins that act as catalysts to increase the speed of chemical rxns

lower activation energy

don’t change total amount of energy relased

just regulate RATE of rxn

Factors that regulate enzyme activity

Temp

pH

Interact w/ specific substrates (lock and key model)

Kinases

add phosphate

Oxidases

catalyze oxidation-reduction rxns involving oxygen

Isomerases

rearrangement of structure of molecules

Diagnostic value of enzyme levels in blood

In healthy ppl, cellular enzymes are not found in the blood. In diseases that damage cells, these cells release enzymes into the blood. Enzymes serve as biomarkers of disease and tissue damage

Example of diagnostic application of enzymes

Elevated lactate dehydrogenase or creatine kinase in the blood may indicate a myocardial infarction (blockage).

When there’s a blockage, muscles below don’t receive enough O2 so the mitochondria can’t make ATP in sarcolemma and heart membrane gets damaged.

Creatine kinase found in blood

myocardial infarction

muscular dystrophy

muscle damage

Alkaline phosphatase

Carcinoma of bone

Paget’s disease

Obstructive jaundice

Amylase in blood

Pancreatitis

Perforated peptic ulcer

Aldolase in blood

Muscular dystrophy

Temp and enzyme activity

Small rise on body temp increases enzyme activity

Exercise results in increased body temp

Large increase in body temp can denauture enzymes and decrease activity

pH and enzyme activity

changes in pH can decrease enzyme activity

high intensity exercise secreases muscle pH