Download Atoms, Elements, Energy, Bonds, Reactions

Atoms and Molecules
General
What are you?
a collection of carefully arranged atoms and
molecules
How does your body work?
all physiology from organism to cell involves
chemical reactions
the physiology of the organism is just the sum
total of all the chemical reactions occurring in individual cells
to maintain “yourself” you must continually
replenish nutrients
takes energy to do that
So, food contains both nutrients or building blocks and molecules that can be
used to make energy
the whole process is regulated by your “genes” – the genetic information
contained within each cell
tells what to do and what is needed to do it
assembly instructions
as long as you give your body the energy and nutrients it needs it can run
“automatically”
Nutrient
A nutrient is any component of the food that we eat that our body needs to
function properly
some of these nutrients are individual atoms or
elements
some of these nutrients are molecules that we
need but that our body is unable to make for itself
some of these nutrients we use mainly as
“building blocks”
some cells functions by manipulating energy and matter = metabolism
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“homeostasis” keeps all systems and processes in
balance
What nutrients do we need?
start by looking at the composition of body:
the body is mainly made up of water and organic
molecules
Human body (100 lbs):
100%
Atoms and Inorganic Molecules
65%/lbs
62 lbs water
2.5 lb minerals
& inorganics
(59-62%)
(2.5%)
Organic Molecules
18 lbs fat
35%/lbs
1.5 lbs carbos
16 lbs proteins
.5 lb nucleic acids
(14-20%)
another source says 18-30
(1-2%)
another source says 2-3
(15-18%)
another source says 12-30
(<1%)
more basic:
what are these made of? elements (atoms)
water: H & O
organic molecules: C, H, O, N, P
minerals: Ca, Fe, Mg, Cu, Zn, etc
nutrient = any of the atoms or molecules that the body requires to function
properly
some of the nutrients we eat are individual atoms or elements
some are molecules that our body needs but cannot make itself
Essential vs Nonessential Nutrients
the body can make some molecules itself given
proper elements
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45 –50 different nutrients are essential nutrients
can’t make them ourselves
must be in food
eg. basic elements, some molecules
Elements:
macronutrients
micronutrients
C
18.5%
Cr, Co
H
9.5%
Cu, F
O
65%
Mo, Se
N
3.2%
Si, Sn (tin)
P
1.0%
Zn, V
Ca
1.5%
Molecules:
O2 (oxygen gas)
vitamins
8 amino acids
10 essential in children
8 essential in adults
2 fatty acids
What does it use them for?
mainly to make organic molecules:
proteins
carbohydrates
fats
etc.
[not vitamins]
What about energy?
where does our body get the energy to do this?
same
So food contains two things:
nutrients (=building blocks)
energy
what kinds of energy does body use:
mechanical muscles
electrical nerves
chemical all cells
where does this energy come from?
food = chemical energy
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bonds: break bonds release energy
form bonds use (store) energy
Chemical Bonds
atoms combine to form molecules by forming chemical bonds:
electrons in various orbitals of different atoms interact in specific ways = bonds
such bonds depend on an atom’s electrons characteristics
outer electrons
-most potential energy
-most likely to form bonds
all atoms are in constant motion
when they “bump” into each other they may react to form molecules
thus a chemical bond:
is not an OBJECT
is an ENERGY RELATIONSHIP
1. covalent bonds
electrons are shared between atoms
most bonds
single, double or triple
can be nonpolar or polar
most stable kind of bond
(bond energy = 80-110 kcal/mole)
2. ionic bonds
when an atom gives up electron to another
no such thing as a “molecule” of salt, in water the ions
disperse,
only held together in crystal form
[oxidation e- given up; eg Na is a reducing
agent for Cl]
[reduction receives e-; Cl reduces Na]
cation
=
+ charged ions
anions
=
- charged ions
[Na; atomic # = 11]
[Cl ; atomic # = 17]
redox also may involve H atoms transferred
(bond energy = 5 kcal/mole)
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3. hydrogen bonds
contains about 5% the strength of covalent bonds
occur between polar molecules (covalent bonds)
some molecules have an uneven distribution of
electrons in covalent bondspolar
hydrogen bonds tend to draw molecules or
parts of molecules together
serve as bridges between different molecules
or different parts of same molecule
can be formed or broken easily
extremely important in stability of many large
organic molecules
also give some unique properties to molecues
eg. Water
(bond energy = 4-6 kcal/mole)
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Chemical Reactions
Chemical bonds are formed or broken in chemical reactions:
a chemical reaction is any process in which some chemical bons are broken or
made
A. synthesis – combining to form more complex
substances
A + B AB
eg. dehydration synthesis (condensation)
eliminates water to synthesize larger
molecules
uses energy
B. decomposition – break down into simpler
substances
AB A + B
eg. hydrolysis
uses water to break down larger molecules
releases energy
C. displacement or exchange
A + BC AC + B
D. reversible
Metabolism = synthesis + decompositon
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