Energy Transfer & Systems

The energy needs of life• Organisms are endergonic systems

– What do we need energy for?• synthesis (new cells, tissues…)• reproduction• movement• active transport• temperature regulation

Energy – the capacity for work

• Extracting energy from nutrients and transferring it to skeletal muscle

• Energy: dynamic state related to change• As work increases, energy transfer increases =

producing a change• Law of thermodynamics: Conservation of energy

• Body does not produce or consume energy transformed from one state into another

Potential & Kinetic Energy• Potential & Kinetic energy make up total

energy of a system

• Releasing potential energy from bond of molecules transformed into kinetic energy of motion

Energy-Releasing & Energy-Conserving Processes

• Exergonic: Physical or chemical process that releases or frees energy

• Endergonic: Chemical processes that store or absorb energy

Forms of Energy

• Light Energy• Heat energy• Chemical Energy• Mechanical Energy • Nuclear Energy• Electric Energy

Examples of Energy Conversions

• Photosynthesis: energy from sun is used to create and supply food in plant cells & store it as potential energy

• Respiration: Reverse of photosynthesisCells extract chemical energy stored in the carbohydrates (food) to supply body with energy for movements (kinetic energy)

Biological work in humans

• Work takes on one of three forms:

1. Mechanical Work Work generated by muscle contractions provides movement

2. Chemical WorkWork by cells to sysnthesize new tissue or tissue growth

3. Transport WorkWork by concentration movements diffusion

Factors that affect energy

1. Enzymes – accelerate rates of chemical reactions = reduce the energy required to initiate a reaction

2. Rate of reaction – rate of enzyme action is influenced by temperature & pH

3. Coenzymes – some enzymes remain inactive until coenzymes activate them facilitate enzyme action

ATP

Living economy• Food = carbohydrates, lipids, proteins, nucleic acids

– break them down• digest = catabolism

– capture released energy in a form the cell can use

• Need an energy currency– a way to pass energy around– a short term energy

storage molecule

Introduction to ATP

• Energy in food does NOT transfer directly into cells

• It must first be converted to ATP only usable source of energy in the body

• ATP = Adenosine Triphosphate

• Potential energy stored in thebonds of this molecule powers all energy requirements of cells

• All energy is stored in the bonds of compounds—breaking the bond releases the energy

• When the cell has energy available it can store this energy by adding a phosphate group to ADP, producing ATP

• ATP is converted into ADP by breaking the bond between the second and third phosphate groups & releasing energy for cellular processes.

phosphate removed

• ATP transfers energy from the breakdown of food molecules to cell functions.

– Energy is released when a phosphate group is removed.

– ADP is changed into ATP when a phosphate group is added.

• Fats store the most energy– 80 percent of the energy in the body

• Proteins are least likely to be broken down to make ATP– amino acids not usually needed for energy– about the same amount of energy as a

carbohydrate

Cellular Respiration:

2 kinds Aerobic or Anaerobic

• Cellular respiration is the process by which the energy of glucose is released in the cell to be used for life processes (movement, breathing, blood circulation, etc…)

• Respiration occurs in ALL cells & can take place either with or without oxygenpresent.

Aerobic Respiration

• Requires oxygen

• Occurs in the mitochondria of the cell

Human cells contain a specialized structure – the

mitochondrion – that generates energy.

Aerobic Respiration

This type of respiration is used when the body continues an activity for a prolonged period of time.

The energy that is needed to allow this prolonged activity is produced using oxygen.

Aerobic Respiration

• In order for the aerobic system to function effectively, there has to be a constant supply of oxygen to the body and the working muscles.

• For any activity that takes place over a long period of time (e.g. Marathon)

• Important to have this constant supply of oxygen to the body otherwise the body would be unable to carry out the event.

Aerobic Respiration

• Aerobic respiration takes place in almost all living things.

• The aerobic respiration is a high energy yielding process.

• Up to 38 molecules of ATP are produced for every molecule of glucose that is broken down.

Aerobic Respiration

Anaerobic Respiration:

• Occurs when no oxygen is available to the cell

• Also called fermentation

• Much less ATP produced than in aerobic respiration

Anaerobic Respiration

• When Oxygen is not available, anaerobic respiration occurs in humans.

• Anaerobic respiration can take place during vigorous exercise, building up lactic acid in muscle tissue. This = muscle pain & cramping.

• During anaerobic respiration 2 molecules of ATP (energy) are produced for every molecule of glucose that is broken down.

Anaerobic Metabolism

Anaerobic metabolism is inefficient:=Large amounts of glucose are used for very small

ATP made.

– Lactic acid is produced whose presence contributes to muscle fatigue

Type of sports uses anaerobic metabolism:– Sports that requires bursts of speed and activity, e.g.,

basketball.

Anaerobic Respiration

What is the difference between Aerobic and Anaerobic Respiration?

Q. Aerobic respiration occurs in the presence of...

A. OxygenExample of an Aerobic activity – Marathon

RunningQ. Anaerobic respiration occurs in the ABSENCE

of...A. OxygenExample of Anaerobic activity – 100m Sprint

Aerobic or Anaerobic?

Aerobic or Anaerobic?

Aerobic or Anaerobic?

Aerobic or Anaerobic?

Aerobic or Anaerobic?