Download Chapter 2 - Orange Coast College

Chapter 2
Chemical Composition of the
Body
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Atoms


Smallest units of matter that can
undergo chemical change.
Nucleus (center) contains:
Protons (+ charge)
 Neutrons (no charge)


Atomic mass:

Sum of protons and neutrons.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Atoms

Atomic Number


Neutral atom


Number of protons in an atom
Number of protons = number of electrons
Isotopes



Vary in number of neutrons
Same in atomic number
Vary in atomic mass
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Atoms

Chemical element


Includes all of the isotopic forms of a given
atom
Eg: Element Hydrogen: 3 isotopes



Most common: one proton
Deuterium: one proton, one neutron
Tritium: one proton, two neutrons


Commonly used in research
106 chemical elements
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Elements

Four elements important to living
organisms




Carbon (C)
Nitrogen (N)
Oxygen (O)
Hydrogen (H)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Atoms

Electrons (outside the nucleus):



- charged
Occupy orbitals surrounding nucleus.
Valence electrons:


Electrons in the outer most orbital that
participate in chemical reactions (if orbit
incomplete).
Form chemical bonds.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Orbitals



Also called shells or energy levels
Electrons usually found within a given
orbital
Levels (and max number of electrons)



First shell: 2 electrons
Second shell: 8 electrons
Third shell: usually 8 electrons
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Chemical Bonds, Molecules,
and Ionic Compounds

Chemical bonds:


Interaction of valence electrons
between 2 or more atoms.
# bonds determined by # electrons
needed to complete outer orbital.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Covalent Bonds


Atoms share their valence
electrons.
Nonpolar bonds:
Electrons are equally distributed
between the two identical atoms.
 Strongest bond.
 H2

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Covalent Bonds

Polar bonds:
Electrons are shared between two
different atoms.
 Electrons may be pulled more toward
more atom.
 Oxygen, nitrogen, phosphate pull
electrons towards themselves.

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Ionic Bonds



One or more valence electrons
from an atom are completely
transferred to a second atom.
First atom loses electrons, +
charged (cation).
Second atom has more electrons,
- charged (anion).
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Ionic Bonds




Cation and anion attract, form ionic
compound.
Weaker than polar bonds.
Dissociate easily when dissolved in
H20.
NaCl
Na+ and Cl-
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Table Salt, an Ionically Bonded Molecule
Slide number: 1
(–)
(+)
11p
12n
Na
17p
18n
+
Cl
11p
12n
+
NaCl
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
17p
18n
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Table Salt, an Ionically Bonded Molecule
Slide number: 2
17p
18n
11p
12n
Na
+
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Cl
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Table Salt, an Ionically Bonded Molecule
Slide number: 3
17p
18n
11p
12n
Na
+
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Cl
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Table Salt, an Ionically Bonded Molecule
Slide number: 4
17p
18n
11p
12n
Na
+
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Cl
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Table Salt, an Ionically Bonded Molecule
Slide number: 5
17p
18n
11p
12n
Na
+
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Cl
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Table Salt, an Ionically Bonded Molecule
Slide number: 6
(+)
(–)
17p
18n
11p
12n
Na
+
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Cl
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Table Salt, an Ionically Bonded Molecule
Slide number: 7
(–)
(+)
17p
18n
11p
12n
NaCl
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Interaction with water

Hydrophilic:
Formation of hydration spheres.
 Polar covalent bonds.


Hydrophobic:
Cannot form hydration spheres.
 Nonpolar covalent bonds.

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Hydrogen Bond


Hydrogen forms a
polar bond with
another atom,
hydrogen has a
slight + charge.
Weak attraction
for for a second
electronegative
atom.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Acids, Bases, and the pH Scale

Acid:



Molecule that can release protons (H+).
Proton donor.
Base:


Negatively charged ion that can combine
with H+.
Proton acceptor.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
pH



pH = log _1__
[H+]
Normal pH blood = 7.35 - 7.45.
Buffer:

System of molecules and ions that
act to prevent changes in [H+].
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Organic Molecules



Molecules that contain carbon and
hydrogen.
Carbon has 4 electrons in outer
orbital.
Carbon covalently bonds to fill its
outer orbital with 8 electrons.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Organic Molecules



Organic Chemistry: deals with
molecules that contain carbon
More than 5 million organic compounds
have been identified
The carbon atom can form bonds with a
greater number of different elements
than any other type of atom
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Functional Groups

Inactive “backbone” to which more
reactive atoms are attached.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Classes According to
Functional Groups



Ketone and
aldehyde: carbonyl
group
Organic acid:
carboxyl group
Alcohol: hydroxyl
group
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Stereoisomers


Exactly the same atoms arranged in
same sequence.
Differ in spatial orientation of a
functional group.



D-isomers: right-handed
L-isomers: left-handed
Enzymes of all cells can combine only
with the L-amino acids and
D-sugars.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Four main classes of
Organic molecules




Lipids
Carbohydrates
Proteins
Nucleic Acids
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Lipids





GR: Lipos=Fat
Diverse group of molecules.
Insoluble in polar solvents (H20).
Hydrophobic (nonpolar)
Consist primarily of hydrocarbon
chains and rings.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Lipids







Hydrocarbons
Fatty acids
Triglycerides
Ketone Bodies
Phospholipids
Steroids
Prostaglandins
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Hydrocarbons



Includes oils and
gases
Carbons can be
single bonds
(saturated)
Carbons can be
double bonded
(unsaturated)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Fatty acids

Nonpolar hydrocarbon chain





Can be saturated (are stright)
Can be unsaturated (bend at the double
bond)
Can be poly unsaturated (multiple bends)
Carboxyl group on one end
Large group
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Triglycerides

Formed by condensation of glycerol and 3
fatty acids.


Ester bond
Fatty acid consists of hydrocarbon chain with
carboxylic acid end.


May be saturated or unsaturated
Saturated fats:



Mostly animal sources
Mostly solid at room temperature
Unsaturated fats


Mostly plant sources
Mostly liquid at room temperature
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Nutritional considerations
of triglycerides



Also called fat or neutral fat
Stored in adipose cells
Total fat intake should be about 30% of
total energy intake


Saturated fat >10%
Saturated fats are implicated in heart
disease and stroke

Data suggests they promote high blood
cholesterol
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Phospholipids



A number of categories
All contain a phosphate group
Most common



Glycerol (3 carbons)
Fatty Acids on carbon 1 and 2
Phosphate group attached to carbon (and
other polar groups eg.: choline)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Lecithin
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Phospholipid

Are amphipathic: contain both polar and
nonpolar domains

Head:



contains polar groups
Hydrophilic
Tail:


Contains fatty acids (nonpolar)
Hydrophobic
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Phospholipids

Major component of cell membranes



Hydrophylic heads orient to water
Hydrophobic tails orient to each other
Kind of phospholipid varies based on
cell or organelle
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Micelle formation
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Ketone Bodies

Results from the hydrolysis of
triglycerides by adipocytes




Liberates free FA into blood
FA function as an acid in blood
Most FA used as energy source by some
tissues
If not, converted by liver into Ketone
bodies
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Ketone Bodies
4-carbon chunks
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Ketone Bodies

Produced in the rapid breakdown of FA




Ketosis: Elevated level of FA in blood
Ketoacidosis: ketosis is high enough to
lower blood ph


Low-carbohydrate diets
Uncontrolled Diabetes mellitus
Can cause coma, death
Filtered by the kidney
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Steroids


Nonpolar and insoluble in H20.
All have cholesterol as precursor.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Prostaglandins

Prostaglandins:
Fatty acid with cyclic hydrocarbon
group.
 Derived from arachidonic acid.

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Prostaglandins
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Carbohydrates



Organic molecules that contain
carbon, hydrogen and oxygen.
CH20
General formula:


CnH2nOn
-ose denotes a sugar molecule
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Carbohydrates

Supply energy



Provide structural support



Glucose
Complex carbohydrates
cellulose
Part of plasma membrane
Monomer: monosaccarides
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Carbohydrates

Monosaccharide: the “simple sugars”

Pentoses (5-carbons):



Ribose: in RNA
Deoxyribose: in DNA
Hexoses (6-carbons):structural isomers


Glucose, fructose and galactose
Characteristics



Soluable
Sweet
Alcoholic fermentation
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Glucose

Also called :


Dextrose
Transportable in the blood


Blood glucose
C6H12O6
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Fructose

Fruit sugar
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Galactose

C6H12O6
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Carbohydrates

Disaccharide:

2 monosaccharides joined covalently.

Sucrose


Maltose


Glucose and fructose
Glucose and glucose
Lactose

Glucose and galactose
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Disaccharides

Characteristics




Sweet
Soluable
Can be fermented
Formation: called condensation




Requires an enzyme
Removal of molecule of water
Also called dehydration synthesis
Formation of a covalent bond
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Formation of Disaccharides
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Hydrolysis



Reverse of dehydration synthesis.
Digestion reaction.
H20 molecule split.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Carbohydrates

Polysaccharides:
Many monosaccharides joined covalently.
 General formula: (C6H10O5)n
 Characteristics:

Devoid of taste
 Do not form solutions
 Iodine test


Iodine +starch+blue
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Polysaccarides

Kinds:

Starch




Dextrins
Glycogen (animal starch)



Glucose subunits
branched
Glucose subunits
Branched
Cellulose


Glucose subunits
Long, unbranched chains
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Proteins

General Information:
GR: proteios=first rank
 ~50% of the organic material of the
body
 Functions


Structural:


Cell structures, CTs
Functional:

Enzymes, hormones, Hb, etc!
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Proteins

Protein Structure
Large molecules (polymers)
composed of amino acid sub-units
(monomers).
 Amino Acid structure

amino group (NH2)
 carboxylic acid group (COOH)
 Radical group (R): functional group
 H

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Proteins

20 different standard amino acids.
Based on the properties of the
functional group
 E.g.:

Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Proteins

Dehydration synthesis:


Amino end of one amino acid
combines with hydroxyl group of
carboxylic end of another amino acid.
Peptide bond:

Bond between two adjacent amino
acids.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Peptide bond
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Proteins



Dipeptide: 2 amino acids
Tripeptide: 3 amino acids
Polypeptide: many amino acids



Number of amino acids varies
Up to 100 aa
Protein


Over 100aa
Great variety!
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Protein structure

Four structural levels

Primary structure



Secondary structure


Based on hydrogen bonding between close aa
Tertiery structure


Based on amino acid sequence
Amino acid sequence determined by DNA
3-D shape
Quaternary structure

Only in proteins with 2 or more polypeptide
chains
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Secondary structure (2o)



Based on the primary structure
Weak hydrogen bonds form between
hydrogen and oxygen of a different amino
acid.
Two main kinds of secondary structure:


Alpha helix: Bond cause chain to twist in a helix.
Beta pleated sheet: interactions between lengths
of the polypeptide chain
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Secondary structures
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Tertitary structure

Polypeptide chains bend and fold.

Based on interactions with aa in different parts of
the polypeptide chain





disulfide bonds: covalent
Hydrogen bonds: weak
Produce 3 -dimensional shapes.
Chemical interaction of each protein produces
own characteristic tertiary structure
Denaturing protein

Irreversible disruption of tertiary structure
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Bonds responsible for 3o
structure
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Tertiary structure
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Quaternary Structure


Number of
polypeptide
chains
covalently
linked
together.
Insulin,
hemoglobin
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Conjugated proteins


Protein combined with another type of
molecule
Glycoproteins: carbohydrate with protein


Lipoproteins: Lipid and protein


Membranes, hormone
Membranes, blood plasma
Hemoproteins: iron and protein

Hemoglobin, cytochromes
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Nucleic Acids

Include the macromolecules:




DNA: deoxyribonucleic acid
RNA: ribonucleic acid
Involved in heredity and genetic regulation
Are polymers:


Monomeric subunit:nucleotides
Bonded together in a dehydration synthesis
reaction
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Nucleic Acids
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Nucleotides

Structure of a nucleotide: 3 subunits



Pentose sugar
Phosphate group
Nitrogenous base

Purines: two rings



Guanine
Adenine
Pyrimidines: one ring



Cytosine
Thymine
Uricil
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Nucleotide Structure
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Nitrogenous Bases
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
DNA



Huge molecules with simple structure
Big time data storage!
Structure

Nucleotides


Pentose sugar: Deoxyribose
Bases:



Purines: G and A
Pyrimidines: C and T
Form double-stranded helix
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
DNA

Nucleotide strands: 2




Sugar-phosphate backbone
Bases stick out
Bases bond to each other
Base pairing:



A–T
G–C
Called law of complementary base pairing
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
Nitrogenous Bases
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
DNA
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
RNA


Means by which DNA directs cellular activities
Structure




Pentose sugar: ribose
Bases: uracil (not thymine)
Single stranded
Three main types



Messenger RNA (mRNA)
Transfer RNA (tRNA)
Ribosomal RNA (rRNA)
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
DNA vs RNA