Transcript Chapter 4 Carbon - Balaji Krishnan

CHAPTER 4
CARBON
AND THE MOLECULAR
DIVERSITY OF LIFE
Learning Objectives
You will be able to
• How the origin of life depended on
organic chemistry
• Explain how and why carbon is a big
part of biology by being the central part
of organic chemistry
• Distinguish among the three types of
isomers: structural, geometric, and
enantiomers.
• Define functional groups of
At the beginning of the 19th century, it
was thought that the substances that
made up living things were special and
could not be synthesized by ordinary
chemical methods. This now-discarded
theory was called the theory of _____.
1.
2.
3.
4.
5.
6.
Evolutionism
Preceptionism
ChemicoBiology
Fantasticism
Fanaticism
Vitalism
In the early 1800s, the German
chemist Friedrich Wöhler and his
students synthesized _____ from
totally inorganic starting materials
1. Urea
2. Acetic Acid
3. Ammonium
Cyanate
4. Insulin
5. DNA
• Vitalism, the idea that organic
compounds arise only in
organisms, was disproved when
chemists synthesized organic
compounds
• Mechanism is the view that all
natural phenomena are
governed by physical and
chemical laws
Miller-Urey Experiment Movie
In 1961, Juan Oro made
amazing quantities of adenine
by just using hydrogen
cyanide and ammonia in an
aqueous solution
1. True
2. False
3. I do not know since this particular
information is not part of our reading
before the class meeting
All the above experiments
resulted in:
1. Organic Chemists rejecting “vitalism” for
“mechanism”
2. Redefining organic chemistry as the study
of carbon compounds
3. Most of the complex and diverse organic
compounds still remain the domain of
production by living organism
Which describe organic
compounds?
1. any compound with carbon
2. While the name, organic compounds, implies that these
compounds can only come from biological processes, they
can be synthesized by non-living reactions.
3. The overall percentages of the major elements of life (C, H,
O, N, S, and P) are quite uniform from one organism to
another.
4. Organic compounds can range from simple molecules, such
as CO2 or CH4, to complex molecules, like proteins, that may
weigh over 100,000 daltons.
5. because of carbon’s versatility, these few elements can be
combined to build an inexhaustible variety of organic
molecules.
6. None of these
7. All of these
Carbon atoms are the most versatile building
blocks of molecules because of:
1. total of 6 electrons; 2 in the first shell, 4 in the second
shell.
2. 19th element in order of mass in the Earth's crust.
3. little tendency to form ionic bonds.
4. sixth most abundant element in the universe.
5. completes its valence shell by sharing electrons.
6. tetravalence by carbon makes large, complex molecules
possible.
7. None of the above
8. All except 4
9. All except 2
CARBON CYCLE – THE MOVIE
Based on the Carbon Cycle
Movie, which statement is true?
1. Excessive combustion can skew the
carbon cycle.
2. Only rabbits are the culprit as far as
global warming is concerned
3. Global warming cannot happen.
4. Planting more trees will be harmful
because carbon dioxide emission will go
up leading to global warming
Determine the valencies
Hydrogen
(valence  1)
Oxygen
(valence  2)
Nitrogen
(valence  3)
Carbon
(valence  4)
CO2
CO(NH2)2
O=C=O
The electron configuration of carbon gives it
compatibility to form covalent bonds with many
different elements.
Which of the following
statement is false?
1. When carbon forms covalent
bonds with four other atoms,
they are arranged at the
corners of an imaginary
tetrahedron with bond angles
near 109o.
2. While drawn flat, they are
actually three-dimensional.
3. When two carbon atoms are
joined by a double bond, all
bonds around the carbons are
in the same plane.
4. C=C have a flat, threedimensional structure
5. All
6. None
Carbon has many skeletons in
its cupboard
(c) Double bond position
(a) Length
Ethane
Propane
(b) Branching
Butane
1-Butene
2-Butene
(d) Presence of rings
2-Methylpropane
(isobutane)
Cyclohexane
Benzene
What are hydrocarbons?
1. From the name, it seems like “hydro”gen and
“carbon” in one or more combinations
2. Candles are composed of hydrocarbons
3. Cooking oils are composed of hydrocarbons
4. Hydrocarbons exist so that I can invest my
money in the oil industry for a comfortable rest
of my retired life
5. They are a brand of refreshing drink like
Gatorade
Hydrocarbons are not prevalent in living organisms,
but many of the cell’s organic molecules have
regions that consist only of carbon and hydrogen
• Fats are biological
molecules that
have long
hydrocarbon tails
attached to a
non-hydrocarbon
component
• Hydrocarbons
release a large
amount of energy
Nucleus
Fat droplets
(a) Part of a human adipose cell
(b) A fat molecule
Isomers
• Isomers are compounds with the same
molecular formula but different structures and
properties
– Structural isomers have different covalent
arrangements of their atoms
– Cis-trans isomers have the same covalent
bonds but differ in spatial arrangements
– Enantiomers are isomers that are mirror
images of each other
What does the following
structure show?
1.
2.
3.
4.
Enantiomer
Stereoisomer
Geometric isomer
Structural isomer
What does the following
structure show?
1.
2.
3.
4.
Enantiomer
Stereoisomer
Geometric isomer
Structural isomer
Geometric Isomers
(also called cis-trans isomers)
(b) Cis-trans isomers
cis isomer: The two Xs
are on the same side.
trans isomer: The two Xs
are on opposite sides.
What does the following
structure show?
1.
2.
3.
4.
Enantiomer
Stereoisomer
Geometric isome
Structural isomer
Mirror Image Isomers
(c) Enantiomers
CO2H
H
CO2H
NH2
CH3
L isomer
NH2
H
CH3
D isomer
Rhodopsin photoisomerization
Molecular change leads to light visualization
http://www.blackwellpublishing.com/matthews/rhodopsin.html
Which of the following is true?
L isomer
D isomer
1. Enantiomers are possible if
there are four different
atoms or groups of atoms
bonded to a carbon.
2. They are like left-handed
and right-handed versions.
3. Usually one is biologically
active, the other inactive.
4. All of the above
5. All except 3
Why Enantiomers Are Important for the
Pharmaceutical Industry?
Drug
Condition
Ibuprofen
Pain;
inflammation
Albuterol
Effective
Enantiomer
Ineffective
Enantiomer
S-Ibuprofen
R-Ibuprofen
R-Albuterol
S-Albuterol
Asthma
Functional Groups – Which is
correct?
Testosterone
Estradiol
1.
2.
3.
4.
5.
attachments that replace one or more hydrogen atoms to the carbon
skeleton of the hydrocarbon.
Each functional group behaves consistently from one organic
molecule to another.
The number and arrangement of functional groups help give each
molecule its unique properties.
All of the above
None of the above
 The basic structure of testosterone (male
hormone) and estradiol (female hormone) is
identical.
 Both are steroids with four fused carbon rings, but
they differ in the functional groups attached to the
rings.
 These then interact with different targets in the
body.
•There are six functional
groups that are most
important to the
chemistry of life:
hydroxyl, carbonyl,
carboxyl, amino,
sulfhydryl, and
phosphate groups.
•All are hydrophilic and
increase the solubility of
organic compounds in
water.
Figure 4.9a
Hydroxyl
STRUCTURE
(may be written
HO—)
EXAMPLE
Ethanol
Alcohols
(Their specific
names usually
end in -ol.)
NAME OF
COMPOUND
• Is polar as a result
of the electrons
spending more
time near the
electronegative
oxygen atom.
FUNCTIONAL
PROPERTIES
• Can form hydrogen
bonds with water
molecules, helping
dissolve organic
compounds such
as sugars.
Figure 4.9b
Carbonyl
STRUCTURE
Ketones if the carbonyl
group is within a
carbon skeleton
NAME OF
COMPOUND
Aldehydes if the carbonyl
group is at the end of the
carbon skeleton
EXAMPLE
Acetone
Propanal
• A ketone and an
aldehyde may be
structural isomers
with different properties,
as is the case for
acetone and propanal.
• Ketone and aldehyde
groups are also found
in sugars, giving rise
to two major groups
of sugars: ketoses
(containing ketone
groups) and aldoses
(containing aldehyde
groups).
FUNCTIONAL
PROPERTIES
Figure 4.9c
Carboxyl
STRUCTURE
Carboxylic acids, or organic
acids
NAME OF
COMPOUND
EXAMPLE
• Acts as an acid; can
FUNCTIONAL
PROPERTIES
donate an H+ because the
covalent bond between
oxygen and hydrogen is so
polar:
Acetic acid
Nonionized
Ionized
• Found in cells in the ionized
form with a charge of 1– and
called a carboxylate ion.
Figure 4.9d
Amino
STRUCTURE
Amines
NAME OF
COMPOUND
EXAMPLE
•
FUNCTIONAL
PROPERTIES
Acts as a base; can
pick up an H+ from the
surrounding solution
(water, in living
organisms):
Glycine
Nonionized
•
Ionized
Found in cells in the
ionized form with a
charge of 1.
Figure 4.9e
Sulfhydryl
STRUCTURE
Thiols
NAME OF
COMPOUND
•
Two sulfhydryl groups can
react, forming a covalent
bond. This “cross-linking”
helps stabilize protein
structure.
FUNCTIONAL
PROPERTIES
•
Cross-linking of cysteines
in hair proteins maintains
the curliness or straightness
of hair. Straight hair can be
“permanently” curled by
shaping it around curlers
and then breaking and
re-forming the cross-linking
bonds.
(may be
written HS—)
EXAMPLE
Cysteine
Figure 4.9f
Phosphate
STRUCTURE
Organic phosphates
EXAMPLE
•
FUNCTIONAL
Contributes negative
charge to the molecule PROPERTIES
of which it is a part
(2– when at the end of
a molecule, as at left;
1– when located
internally in a chain of
phosphates).
•
Molecules containing
phosphate groups have
the potential to react
with water, releasing
energy.
Glycerol phosphate
NAME OF
COMPOUND
Figure 4.9g
Methyl
STRUCTURE
Methylated compounds
EXAMPLE
•
Addition of a methyl group FUNCTIONAL
PROPERTIES
to DNA, or to molecules
bound to DNA, affects the
expression of genes.
•
Arrangement of methyl
groups in male and female
sex hormones affects their
shape and function.
5-Methyl cytidine
NAME OF
COMPOUND
If you were to design an entire planet’s
biology but the only element not available was
carbon, what other element could you use?
1.
2.
3.
4.
5.
6.
7.
8.
Gold
Silver
Silicon
Cadmium
Uranium
Nickel
Arsenic
None of the above