Respiration – A2

A Stangroom

Life requires a continuous supply of energy.

Organic molecules can be used as building blocks or as potential chemical energy which is released from the breakdown of molecules in respiration

This energy is used to do work

Energy is required in the form of ATP

ATP ADP + Pi + 30.5 KJ mol-1

ADP AMP + Pi + 30.5 KJ mol-1

AMP Adenosine + Pi + 14.2 KJ mol-1

ATP + H2O ADP + H3PO4 + 30.5 KJ mol-1

At rest an average person uses 40Kg of ATP in 24 hours only 5g is present at any time

During exercise ATP is broken down at the rate of 0.5g per minute

ATP is the universal intermediary moleculebetween energy yielding and energy requiring cell reactions energy currencytransfer is inefficient; some is lost as thermal energy

Energy storage molecules are:Long term: glycogen, starch, fatShort term: glucose, sucrose

Energy is required for WORK :

Anabolic reactions (synthesis) e.g. amino acids proteins

Active transportMovement against diffusion gradient e.g.sodium/potassium pump

Movementcilia, flagella, cytoplasmic streaming and muscles Energy is used to bring about the movement of two protein strands relative to each other

Muscle made of muscle fibres, made of bundles of myofibrilsThey are elongated cells containing myofilaments – actin and myosin

actin (thinner) and myosin (thicker) are protein strandsThe cells also have many mitochondria And specialised ER called sarcoplasmic reticulum which releases calcium

Myosin has a rod shaped region attached to a globular head that acts as ATP-ase the head can attach to actinActin is made of two helical protein strands twisted together

myosin

Actin