nutrients and energy metabolism

lec 12

what is energy

ability to do work

what is energetics

energy transfer between systems

2 types of energy

1. potential- trapped energy

2. kinetic- energy of movement

heat

• radiant energy- transmitted from one object to another

• thermal energy- movement of molecules

mechanical energy

movement of objects

electrical energy

movement of charged particles down a acharge gradient

chemical energy

within chemical bonds

animals rely on

all five types of energy which are interconvertible

1. radiant

2. thermal

3. mechanical

4. electrical

5. chemical

chemical bonds

most biologically available energy

two main types:

• covalent

• noncovalent

covalent bonds (strong bonds)

individual atoms held together by the sharing of electrons

non covalent bonds (weak bonds)

molecules organized into 3d structure

van der waal bonds in geckos

when van der waal forces are used together it can withhold a lot of strength

chemical energy is totipotent

‘all powerful’-can be used for all forms of physiological work

why is mechanical energy not totipotent

can pump blood but cant make proteins

why is electrical energy not totipotent

can set ions in motion but cant make proteins

why is heat not totipotent

heat cannot do any physiological work

• heat is a byproduct of physiological processes

energy storage

cells store energy in two main forms

• reducing energy

• high energy bonds

energy can be ‘stored’ in

covalent bonds

• energy is released when bonds are broken

• atp is the most common ‘high energy’ molecule

in animals and plants, energy is not stored as atp but..

lipids, carbs, proteins/amino acids

food goes in..

• enzymes convert nutrients to metabolites

• metabolites broken down to release energy

• metabolites converted to acetyl CO-a

• A-CoA turned into 3 NADH and 1 FADH2 and CO2

animal use energy to perform 3 major functions

1. biosyntehsis

2. matintenance

3. generation of external work

some energy lose as heat

animal energy use- biosynthesis

synthesis of body constituents (lipids, carbs, proteins)

• food→nutrients→ metabolites

• create/synthesize new cells or tissues

• some products lost to the environment

animal energy use- maintenance

maintains integrity and normal function of the body

animal energy use-generation of external work

applying mechanical force to objects outside of the body

atp supply routes

• free atp

• phosphagen

• anaerobic glycolysis (no O2)

• oxidative metabolism (use O2)

free atp

instant, only a few seconds

phosphagen

• creatine phosphate

• very fast atp production for short duration

• fast enzymatic replenishment: creatine phosphokinase

C-P→creatine

C-P release a P, turns ADP→ATP

creatine is a product

anaerobic glycolysis (no oxygen)

• fast atp production for moderate

• glucose, glycogen supply in muscle

• energy inefficient

oxidative metabolism (using O2 in environment)

• slow atp production for long duration

• energy efficient: can produce 34 ATP molecules

  • nadh→3 molecules of atp

  • fadh2→2 molecules of atp

transformation of high grade energy is

inefficient

output/input

glucose to atp=70% converted to atp

atp to muscular motion=25-30% into muscles motion