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1. Chemistry of Life
Almost 60 chemical elements are found in the body, but the
purpose for every one of those elements is still unknown.

2. Outline
•Elemental Composition
•Atomic Structure
•Chemical Bonds
•Metabolism
•Compounds of Life

3. Atomic Composition

4. 96% (by mass)
•Oxygen
•Carbon
•Hydrogen
•Nitrogen
Mostly in the form of water

5. Life depends on a precise balance
between all of those chemicals
•Potasium deficiency  abnormal
heart beat
•More Sodium  high blood
pressure
•Medications  treat diseases

6. MATTER
is anything that has mass and occupies space. In
turn, matter consists of substances that can be
either elements or compounds
ELEMENTS
are pure substances:
they can’t be broken
down or decomposed
into two or more
substances.
COMPOUNDS
are chemical
combinations of two or
more elements.

7. ELEMENTS
are pure substances: they can’t
be broken down or
decomposed into two or more
substances. One example is
oxygen; oxygen can’t be broken
down or decomposed into
anything but oxygen.
COMPOUNDS
are chemical combinations of
two or more elements.
(For example, water is a
compound that results from the
combination
of hydrogen and oxygen.
Hydrogen and oxygen are
elements, each
having their own unique
properties; in turn, the
properties of water
are entirely different than those
of either hydrogen or oxygen.)

8. Name Symbol Percentage of
Body Weight
Oxygen O 65.0
Carbon C 18.0
Hydrogen H 10.0
Nitrogen N 3.0
Calcium Ca 1.5
Phosphorus P 1.0
Major Elements
These six elements account for 98.5% of the
body’s weight.

9. Name Symbol Percentage of
Body Weight
Sulfur S 0.25
Potasium K 0.20
Sodium Na 0.15
Chlorine Cl 0.15
Magnesium Mg 0.05
Iron Fe 0.008
Lesser Elements
These six elements account for 0.8% of the
body’s weight.

10. Trace Elements
These 12 comprise just 0.7% of the body’s
weight. Although minute in quantity, each is
necessary for the body to function properly.

11. FAST FACT
If the body becomes contaminated with
elements that don’t serve a purpose in
the body—such as lead or mercury—
serious illness or disease may occur. For
example, exposure to lead or mercury can
lead to heavy-metal poisoning.

12. Elements
98.5% 0.8%
0.7%

13. Atom

14. Isotopes

15. Isotopes
•Same chemical properties
•Some are unstable, releases neutrons
•Radioactivity
•Radiation can damage cells
•Radiation therapy

16. Radiation
• We are continually exposed to low levels of radiation
in the environment—including from light and radio
waves.
• This level of radiation exposure is harmless.
• Higher levels of radiation damage cells and tissues.
• That’s why radiation therapy is used to kill cancer
cells.
• Excessive levels of radiation can cause radiation
sickness, a condition that can be mild or, depending
upon the level of exposure, fatal.

17. Life Lesson: Radiation Therapy
• Radioactive isotopes emit particles as they break down.
• When those particles strike atoms in living cells, they injure or kill the
cells.
• Knowing this, doctors often use radiation to treat patients with
cancer.
• In fact, about half of all cancer patients receive some type of
radiation therapy as part of their treatment.
• Although radiation damages healthy cells along with the cancer cells,
most healthy cells can recover from the effects of the radiation.
• The goal of the therapy is to damage as many cancer cells as possible
while limiting the damage to nearby healthy tissue.

18. Life Lesson: Radiation Therapy
•The type of radiation therapy given depends the
type and location of the cancer as well as the
goal of treatment.
•Sometimes the goal is to completely destroy the
tumor.
•Other times, the goal is simply to shrink the
tumor to help relieve symptoms.

19. Life Lesson: Radiation Therapy
• Most often, a machine is used to deliver radiation to the outside of
the body.
• Sometimes radiation may be implanted directly inside the tumor in
the form of a tube, wire, capsule, or seeds.
• Radioactive material also may be administered orally or through an
intravenous catheter.
• A new method of radiation therapy involves injecting tumor-specific
antibodies that have been attached to a radioactive substance.
• Once inside the body, the antibodies seek out cancer cells, which are
then destroyed by the radiation.

20. Chemical Bonds

21. An atom with a full outer shell is said
to be stable

22. Most atoms are not stable,

23. They’re drawn to other atoms as they attempt to lose,
gain, or share the electrons in their outer shells
(called valence electrons) so as to become stable.
This type of interaction results in a molecule: a
particle composed of two or more atoms united by a
chemical bond

24. Types of Chemical Bonds
•Ionic Bond
•Covalent bond
•Hydrogen bond

25. Ionic Bonds
•Formed when one atom transfers an electron
from its outer shell to another atom.
•Because electrons are negatively charged, when
an atom gains or loses an electron, its overall
charge changes from neutral to either positive or
negative.
•These electrically charged atoms are called ions.
•Atoms having a positive charge are cations;
•Those with a negative charge are anions.

26. Example

29. Ionization: When dissolved in water, ionic bonds
tend to break, or dissociate, creating a solution of
positively and negatively charged ions that’s
capable of conducting electricity.

30. Compounds (such as
NaCl) that ionize in
water and create a
solution capable of
conducting electricity
are called electrolytes.

31. Electrolytes are crucial for
•heart, nerve, and muscle function;
•the distribution of water in the
body;
•and the occurrence of chemical
reactions.

32. A few of the body’s
major electrolytes include
•calcium chloride (CaCl2),
•Magnesium chloride (MgCl2),
•Potassium chloride (KCl),
•and sodium bicarbonate (NaHCO3).

33. Electrolyte Balance
•Maintaining electrolyte balance is a
top priority in patient care.
•Imbalances in electrolytes can
cause problems ranging from
muscle cramps to cardiac arrest.

34. Covalent bonds
•Covalent bonds are formed when two
atoms share one or more pairs of electrons
as they attempt to fill their outer shells.
• The major elements of the body (carbon,
oxygen, hydrogen, and nitrogen) almost
always share electrons to form covalent
bonds.

35. • Hydrogen has one shell with one electron. The inner
shell would be full, and the atom stable, if it had two
electrons.
• If two atoms of hydrogen share their one electron, a
single covalent bond exists and hydrogen gas (H2) is
formed.

36. Double covalent bonds may also occur, in which
atoms are bound together through the sharing of
two electrons.
• Oxygen needs two
electrons to complete its
outer shell. Carbon needs
four electrons to complete
its outer shell.
• When one carbon atom
shares one pair of
electrons with two oxygen
atoms—completing the
outer shells for all three
atoms—a molecule of
carbon dioxide is formed

37. Covalent Bonds
•Covalent bonds are stronger than ionic bonds,
• and they’re used to create many of the chemical
structures found in the body.
•For example, proteins and carbohydrates are
formed through a series of covalent bonds.
•The fact that covalent bonds don’t dissolve in
water allows molecules to exist in the fluid
environment of the body.

38. Hydrogen Bond
•Whereas a covalent bond forms a new molecule,
a hydrogen bond does not.
•Rather, a hydrogen bond is a weak attraction
between a slightly positive hydrogen atom in
one molecule and a slightly negative oxygen or
nitrogen atom in another.

39. Hydrogen Bond - Water
• Water consists of two hydrogen atoms
bonded (with covalent bonds) to an oxygen
atom.
• In the bonding process, oxygen shared two
of the electrons in its outer shell with
hydrogen. Even after bonding, it has four
additional electrons in its outer shell. These
unpaired electrons give water a partial
negative (- ) charge near the oxygen atom.
• At the same time, the two hydrogen atoms
create a slight positive ( +) charge on the
other side of the molecule.
• ●Therefore, although water is electrically
neutral, it has an uneven distribution of
electrons. This makes it a polar molecule.

40. The partially negative oxygen side of one water
molecule is attracted to the partially positive hydrogen side of
another molecule. This attraction results in a weak attachment
(hydrogen bond) between water molecules.

41. Basic Processes of Life
•The microscopic world of atoms and chemical
bonds forms the foundation of life.
•These substances are constantly at work,
creating the precise internal environment for
survival and providing cells and organs with the
energy they need to function.

42. Energy
• Capacity to do work: put matter into motion
• Moving a muscle or moving a blood cell.
• The body works continually—
•pumping blood,
•creating new cells,
•filtering out waste,
•producing hormones—
•and therefore needs a constant supply of energy.

43. Energy
Potential Energy
it has the potential to do
work; it’s just not doing
work at that moment.
Stored in the bonds of
molecules
Kinetic Energy
Energy in motion
Chemical reactions
release the energy and
make it available for the
body to use

44. Metabolism
The sum of all chemical reactions in the body
Catabolism
• Breaking down complex compounds
(such as large food molecules) into
simpler ones.
• The breaking of chemical bonds
releases energy.
• Some of the energy released is in the
form of heat, which helps maintain
body temperature.
• Most of it is transferred to a molecule
called adenosine triphosphate (ATP),
which, in turn, transfers the energy to
the cells.
Anabolism
• This involves building larger and
more complex chemical molecules
(such carbohydrates, lipids,
proteins, and nucleic acids) from
smaller subunits.
• Anabolic chemical reactions require
energy input.
• The energy needed for anabolic
reactions is obtained from ATP
molecules.

45. Chemical Reactions involve the formation
or breaking of chemical bonds.
A + B → AB
reactants products

46. Types of Chemical Reactions

47. Molecules—including the molecules
in the body— are constantly moving.
When mutually reactive molecules
collide with each other—in just the
right way with the right amount of
force— a reaction occurs.

48. Factors that affect reaction rates are:
• Temperature: Heat speeds up molecular movement,
increasing the frequency and force of collisions between
molecules.
• Concentration: In concentrated solutions, molecules are more
densely packed, increasing their rate of collision.
• Catalysts: These are chemical substances that speed up the
rate of a reaction. Protein catalysts are called enzymes. Most
metabolic reactions inside cells are controlled by enzymes.

49. Compounds of Life
InOrganic
•Water
•Oxygen
•CO2
•Acids
•Bases
Organic
•Carbohydrates
•Lipids
•Proteins
•Nucleic acids

50. Water
•50% or more of an adult’s body weight is water:
•Exists within and around cells
•An essential component of blood.
•Unlike any other fluid, water has a number of
characteristics that make it essential for life.

51. Characteristics of Water

52. Oxygen and Carbon Dioxide
•Involved in the process of cellular respiration—
the production of energy within cells.
•Cells need oxygen to break down nutrients (such
as glucose) to release energy.
•In turn, the process releases carbon dioxide as a
waste product.
• Although it’s a waste product, carbon dioxide
plays a crucial role in the maintenance of acid-
base balance

53. Measuring Energy Consumption

54. Acids
• releases a hydrogen ion (H+)
when dissolved in water.
• proton donors
• taste sour
• turn litmus paper red
Bases
• releases a hydroxyl ion (OH-)
when dissolved in water.
• proton acceptors
• taste bitter
• turn it blue

55. Organic Compounds
Carbohydrates
• Commonly called sugars or starches,
• The body’s main energy source.
• The body obtains carbohydrates by eating foods that contain
them (such as potatoes, vegetables, rice, etc.).
• Then, through metabolism, the body breaks down
carbohydrates to release stored energy.
• All carbohydrates consist of carbon, hydrogen, and oxygen;
• The carbon atoms link with other carbon atoms to form
chains of different lengths.
• The chains consist of units of sugar called saccharide units.

56. Monosaccharides
Contain one sugar unit.
Disaccharides
Contain two sugar units.
Polysaccharides
Consist of many sugar units joined
together in straight chains or complex
shapes.

57. There are three primary monosaccharides:
•Glucose: the primary source of energy used by
most of the body’s cells
•Fructose: found in fruit; it’s converted to glucose
in the body
•Galactose: found in dairy products; it’s also
converted to glucose in the body

58. Three important disaccharides are:
•Sucrose (table sugar) : glucose + fructose
• Lactose (milk sugar) : glucose + galactose
•Maltose (found in germinating wheat) glucose +
glucose

59. Commonly called complex carbohydrates,
polysaccharides include:
•Glycogen
•Starch
•Cellulose

60. Glycogen: the stored form of glucose

61. Starch
•The form in which plants store polysaccharides
•Rice, potatoes, and corn are examples of foods
high in starch.
•When consumed, digestive enzymes split the
starch molecule, releasing glucose.

62. Cellulose:
•Produced by plant cells as part of their cell walls
•Humans can’t digest cellulose and, therefore,
don’t obtain energy or nutrients from it.
•Even so, cellulose supplies fiber in the diet,
which helps move materials through the
intestines.

63. Lipids
•Composed mostly of carbon, hydrogen, and
oxygen,
•lipids are a large and diverse group.
•Insoluble in water.

64. Lipids serve several major roles
•reserve supply of energy,
•providing structure to cell membranes,
•insulating nerves,
•serving as vitamins,
•and acting as a cushion to protect organs.

65. Types of lipids
•Triglycerides,
•steroids,
•phospholipids

66. Triglycerides
•The most abundant lipid
•Function as a concentrated source of energy in
the body.
•Also called fats
•Result when one molecule of glycerol combines
with three fatty acids

67. Saturated Fatty Acids Unsaturated Fatty Acids

68. Saturated Fatty Acids
• Consist of carbon atoms that are
saturated with hydrogen atoms:
each carbon atom in the
hydrocarbon chain is bonded to
the maximum number of
hydrogen atoms by single
covalent bonds
• Form a solid mass at room
temperature (because the linear
structure of the chains allows
them to pack closely together)
• Usually derived from animal
sources
Unsaturated Fatty Acids
• Consist of carbon atoms that are
not saturated with hydrogen
atoms: the hydrocarbon chain
contains one or more double
bonds
• Are liquid at room temperature
(because kinks in the chain
caused by the double bonds
prevent the molecules from
packing tightly together)
• Called oils
• Derived mostly from plant
sources

69. Steroids
•Steroids are a diverse group of lipids that fulfill a
wide variety of roles.
• The most important steroid—the one from
which all other steroids are made—is
cholesterol.
•Although high cholesterol levels have been
implicated in heart disease, it remains an
important component of the body.

70. For example cholesterol:
• is the precursor for other steroids, including the sex
hormones (estrogen, progesterone, and testosterone),
bile acids (that aid in fat digestion and nutrient
absorption), and cortisol
• contributes to the formation of vitamin D
• provides each cell with its three-dimensional structure
• is required for proper nerve function.
• About 85% of cholesterol is synthesized in the liver;
the remaining 15% is consumed through diet.

71. Phospholipids
•These fat compounds are similar to triglycerides,
•Except that phospholipids have a phosphate
group in place of one of the fatty acids.
•Phospholipids help form the structure of cell
membranes.

72. Proteins
•Proteins are the most abundant, and most
important, organic compounds in the body.
•The structure of every cell, not to mention most
of its metabolic functions, depend on proteins

73. Role of Proteins in the Body
• Keratin gives strength to nails, hair, and skin surface.
• Collagen lends structure to bones, cartilage, and
teeth.
• Antibodies defend the body against bacteria.
• Enzymes act as catalysts for crucial chemical reactions.
• Contractile proteins promote muscle contraction.
• Hemoglobin carries oxygen in the blood.
• Hormones, such as insulin, serve as chemical
messengers to cells throughout the body.

74. •Proteins are very large molecules consisting of
smaller chemical subunits called amino acids.
•All amino acids contain carbon, oxygen,
hydrogen, and nitrogen; some are modified by
the addition of sulfur, iron, and phosphorus.
•There are 20 different amino acids; 11 can be
manufactured by the body, whereas nine must
be obtained from food.
• All amino acids have a central carbon atom with
an amino group (NH3) and a carboxyl group
(COOH) bonded to it.

75. What differentiates the amino acids from each other is
what’s called the R group. The R group can be anything,
ranging from a single hydrogen atom (as in the amino
acid glycine) to a complex configuration of hydrogen
and carbon.

78. Protein Structure
•Amino acids link to each other through peptide
bonds

79. The peptide bond
forms when the
carboxyl group of
one amino acid
links to……
…the amino group
of another amino
acid.
In the process, a
molecule of water
is released.

80. Protein Structure
• A short chain of amino acids linked by peptide bonds is
called a polypeptide.
• A protein may contain anywhere from 50 to several
thousand amino acids.
• Each protein has a unique three-dimensional shape, and it’s
this shape that determines the protein’s function.
• Because proteins fulfill roles ranging from the simple to the
very complex, it makes sense that the structures of proteins
range from the simple (primary structure) to the very
complex (quaternary structure).
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https://youtu.be/Pjt1Q2ZZVjA

82. ATP
• Food provides the body with energy.
• However, even when food is broken down, cells can’t
use it directly.
• Instead, cells tap into energy stored within a
nucleotide called ATP (adenosine triphosphate).
• ATP stores the energy released from the breakdown of
nutrients and provides it to fuel cellular reactions.
Here’s how it works:

83. ATP consists of a base, a sugar, and
three phosphate groups.
The phosphate groups are connected to
each other with high-energy bonds.

84. When one of these bonds is broken through a chemical
reaction, energy is released that can be used for work
(such as muscle movement as well as the body’s
physiological processes).

85. After the bond is broken, adenosine triphosphate
becomes adenosine diphosphate (ADP) and a single
phosphate.

86. Meanwhile, the cell uses some of the energy
released from the breakdown of the nutrients in food
to reattach the third phosphate to the ADP, again
forming ATP.