3.3. NUTRITION AND ENERGY SYSTEMS

IB SEHS

Starter

• What distinguishes animal cells versus plant cells?

• Where does respiration occur?

Learning Objectives

Everyone will be able to 1. Identify the different parts of the

mitochondrion.

2. Define and understand respiration

3. Explain the loss and gain of phosphate in an adenosine molecule

The Animal Cell

Mitochondrion Ultrastructure

• Energy provision • Only site where

oxygen is used• Location: All cells,

but red cells• Ultrastructure

shown right

The Energy currency, ATP

• ATP is the energy currency • Adenosine TriPhosphate is a molecule created

from biochemical energy in organic molecules by catabolic reactions.

Cell Respiration

• Cell respiration is the controlled release of energy in the form of ATP from organic compounds in cells

Energy metabolism: ATP

• ATP connects anabolic and catabolic reactions. • Ingested food stored as fats or glycogen

Catabolism ATP Energy

ATP role in muscle contraction

• Actin and myosin use ATP to drive contraction

• Muscle fibers have sufficient ATP for only 2 seconds of contraction. The rest comes from catabolic reactions that generate ATP

• ATP + H2O ADP + P + Energy Contraction

Anaerobic Energy Systems Creatine Phosphate System

• Creatine Phosphate SystemCP is another high energy molecule BUT cannot be used directly. It´s a check we need to first cash into ATP.

• During exercise, after spending our 2 sec worth of ATP, CP helps re-synthesizing ATP, giving energy for up to first 20 sec to muscles

Creatine Phosphate System goes both ways

• The ATP-CP system can go both ways. – During exercise, first 20 sec, ATP is re-synthesized– At rest, ATP can be used to refill our store of PCr in

the muscle

REST <--- --->EXERCISE

Anaerobic Energy Systems Lactic Acid System

• Anaerobic Glycolysis LOCATION: CYTOPLASM of all cells

Glucose ATP + pyruvate • Limited supply of oxygen or

mithocondria leads to Pyruvate Lactate + 2 ATP

• Lactic Acid System is quick and ideal of hard exercise

Anaerobic Energy Systems Lactic Acid System

• Is the Lactic Acid System an ideal system for an elongated period of hard exercise?

• Interpret and comment on the following graph

Aerobic Energy Systems

• Location: MITOCHONDRIA– Electron transport chain

in the inner membrane – Krebs Cycle in the

matrix– β-oxydation in the

matrix

Aerobic Energy Systems

• Glucose Oxydation – Pyruvate acetil CoA Krebs Cycle in the matrix– H+ ions released ELECTRON TRASPORT CHAIN ENERGY AS ATP

Aerobic Energy Systems

• Fat Oxydation– Free fatty acids enter the matrix β-oxydation

Acetil CoA Krebs Cycle H+ Electron transport chain Energy as ATP

– Fat CANNOT BE USED ANAEROBICALLY,unlike glycogen

STARTER

• Discuss in pairs what is the determiant factor for cells to use one energy system or another. Explain in detail.

What Energy System is this one? What is the limitant factor?

THE BIG QUESTION

• How does the elenctron tranport chain help the cell synthesizing ATP?

• https://www.youtube.com/watch?v=Ak17BWJ3bLg

INDIVIDUAL ACTIVITY

• YOU HAVE RECEIVED A MUSCLE CELL (LONG WHITE PAPER)

• DRAW A DIAGRAM, INCLUDING CELL MEMBRANE, CYTOSOL AND MITHOCONDRION WITH DETAIL, IN WHICH THE THREE METABOLIC PATHS ARE SHOWN: ANAEROBIC LACTIC ACID, GLUCOSE AND FATTY ACID OXYDATION. INCLUDE MAIN REACTIONS ONLY

• BE READY TO EXPLAIN YOUR CELL.

Oxygen Deficit and Excess Post-Exercise Oxygen Consumption (EPOC)

• Start of exercise Oxygen need > oxygen supply: O2 DEFICIT ATP, PCr and anaerobic glycolysis activate quicker!

• After exercise Oxygen supply greater than needed: EPOC or O2 DEBT offset consequences of anaerobic metabolism, repair of tissue, myoglobin oxydation, etc.

Oxygen Deficit and Excess Post-Exercise Oxygen Consumption (EPOC)

• Analyze and comment on the following graph:

Contribution of the Energy Systems during exercise

• High intensity exercise high rate of ATP needed Fast metabolism PCr (20 sec) and Lactic Acid System

• Longer & Slower exercise Aerobic metabolism: Glucose and Fat oxydation (slowest one)

• Glucose (anaerobic and aerobic) metabolism is key across all intensities of exercise.

Contribution of the Energy Systems during exercise

Different types of exercise and energy systems contribution