Transcript H - Images

Ch. 4- Carbon and the Molecular
Diversity of Life Structure
& Ch. 5- Function of Macromolecules
Chapters 4 and 5
The Uniqueness of Carbon
Requires 4 electrons to fill its outer shell.
Will form tetrahedral molecules with
other atoms. Has equidistant bond
angles of 109.5°.
Will readily form single, double and triple
covalent bonds.
Carbon forms a variety of chained and
ringed organic compounds.
Carbon is the backbone for many
organic compounds.
Carbon in a Tetrahedron!
Hydrocarbons:
 Are molecules consisting of only carbon
and hydrogen.
 Are found in many of a cell’s organic
Fat droplets (stained red)
molecules.
100 µm
Figure 4.6 A, B
(a) A fat molecule
(b) Mammalian adipose cells
Functional groups are the parts of
molecules involved in chemical
reactions
Functional groups
 Are the chemically reactive groups of
atoms within an organic molecule.
Six functional groups are
important in the chemistry of life
 Hydroxyl
 Carbonyl
 Carboxyl
 Amino
 Sulfhydryl
 Phosphate
 P. 64
Functional groups give organic
molecules distinctive chemical
properties
Estradiol
CH3
OH
HO
Female lion
CH3
OH
CH3
O
Figure 4.9
Male lion
Testosterone
Organic Compounds
Four major groups:
1. Carbohydrates
2. Lipids
3. Proteins
4. Nucleic Acids
Differ in their functional groups
Organic Compounds
Some organic compounds are small
with one or a few functional groupsmonomers. (Ex. Glucose =
monosaccharide).
Other organic compounds are made
from linking several simple monomers
together in complex chains- polymers
(1000’s of glucose monomers =
starch, polysaccharide).
Monomers
Simple

Polymers
Complex
Monosaccharides  Polysaccharides
Glycerol, Fatty Acids Lipids, Fats
Amino Acids 
Proteins
Nucleotides 
Nucleic Acids
Building Macromolecules
All polymers are formed by making
covalent bonds between two
monomers.
The –OH group from one monomer
is removed and the –H from the
other is removed – Dehydration
Synthesis
H2O is removed which requires
energy.
Dehydration Synthesis
HO
H
ENERGY
HO
HO
H
HOH
H
Dehydration Synthesis
When polymers are built from smaller
monomers- anabolic reactions
(synthesizing). Requires energy.
These reactions require the reactants
to be held close together and
chemical bonds to be stressed and
broken-catalysis.
Catalysis is caused by enzymes.
Hydrolysis Reactions
Cells may also disassemble polymers into
monomers- catabolic reactions
(breakdown).
A molecule of H2O is added and split; a H
is added to one monomer and the OH is
added to the other-hydrolysis (water
splitting).
Catabolic reactions release the energy
stored in the bonds of the monomers.
Carbohydrates
Contain C, H, O atoms (CH2O)n
Functions:
Main source of energy- for immediate
use or for energy storage,
Used for structure- on surfaces of cell
membranes (bacteria, eukaryotes), or
support cell walls (plants).
Three Types of Carbohydrates
1. Monosaccharides- “mono”- single;
simple sugars that are made of 3-6 C’s
in a chain or ring.
Ex. C6H12O6 , Glucose, most abundant
monosaccharide
Straight Chain or
Rings
Monosaccharides- Isomers
Three types of isomers are:
 Structural
 Geometric
 Enantiomers
(a) Structural isomers
H
H
H
H
H
H
C
C
C
C
C
H
H
H
H
H
X
(b) Geometric isomers
H
H
H
C
H
C
NH2
CH3
Figure 4.7 A-C
X
CO2H
C
H
H
X
H
CO2H
c) Enantiomers
H
C
C
C
H
C
H
H
H
C
C
H
X
C
H
H
H
C
H
H
NH2
CH3
H
Enantiomers:
Are important in the
pharmaceutical industry.
Figure 4.8
L-Dopa
D-Dopa
(effective against
Parkinson’s disease)
(biologically
inactive)
Isomers
Structural Isomersmonosaccharides with the same
empirical formula but different
structures.
Ex. Glucose and Fructose
Stereoisomers –
monosaccharides that have the
same empirical formula but they
have functional groups as mirror
images of each other.
Ex. Glucose and Galactose
Monosaccharides of
Nucleic Acids
Other Monosaccharides
Fructose- commonly found in
fruit.
Galactose- found in milk.
Ribose- found in RNA.
Deoxyribose- found in DNA.
Monosaccharides
Most offer a number C-H bonds as
potential chemical energy.
May also be used as monomers to
build more complex polymers for
energy storage or structural
molecules.
2. Disaccharides
Are two monosaccharides that form
a glycosidic bond by removing a
H2O molecule.
Glucose + Fructose-->Sucrose
(table sugar)
Sucrose- A Disaccharide
Disaccharides
Monosaccharides (glucose) is often
converted into a disaccharide before
being transported around an
organism’s body.
Unable to be used in this form until
it arrives at a tissue.
Plants transport glucose as sucrose.
(sugar cane)
Lactose
Lactose
Mammals use lactose to transport
glucose to infant.
Adults usually lack the enzyme,
lactase, which breaks down
lactose glucose + galactose.
Other Disaccharides
Sucrose (Table Sugar)- Glucose +
Fructose
Lactose (Milk Sugar)- Glucose +
Galactose
Maltose (Breakdown from Starch)Glucose + Glucose
3. Polysaccharides
Formed when monosaccharides
are linked in chains by glycosidic
bonds.
They are polymers- long chains of
monomers (building blocks).
Polymer = polysaccharide,
Monomers = monsaccharides
Polysaccharides
Two Basic Functions1. Storage Polysaccharides: May
store 1000’s of monomers for
energy. Usually stored in special
storage structures.
2. Structural: May form structural
parts of cells and/or tissues.
Starch = Amylose
Chloroplast
Starch
1 m
Amylose
Figure 5.6
Amylopectin
(a) Starch: a plant polysaccharide
Plant Storage- Starch
Amylose- hundreds of glucose molecules
in a long, unbranched chain.
The glycosidic bond is between the 1C-4C.
The chains coil in water and don’t form H
bonds, therefore not very soluble in H2O.
Only 20% of starch in potatoes is amylose.
80% is amylopectin- short and branched
glucose chains. Is cross-linked.
Starch Storage
Plants use special tissues called
tubers.
Also stored in bulbs of perennials.
Glycogen:
Consists of glucose monomers.
 Is the major storage form of glucose in
animals.

Mitochondria
Giycogen granules
0.5 m
Glycogen
Figure 5.6
(b) Glycogen: an animal polysaccharide
Animal Storage- Glycogen
Insoluble, branched amylose
chains.
Longer and more branched than
starch.
Stored in liver and skeletal
muscle.
Not transported in blood.
Starch
Cellulose
Cellulose has different glycosidic linkages
than starch.
H
O
C
CH2OH
H
4
O
H
OH
H
HO
HO
C
H
H
C
OH
H
C
OH
H
C
OH
OH
OH
H
C
H
H
CH2OH
OH
 glucose
H
O
H
OH
4
HO
OH
1
H
H
H
OH
 glucose
(a)  and  glucose ring structures
CH2OH
CH2OH
O
HO
O
4
1
OH
O
4
O
1
OH
OH
OH
O
O
1
OH
CH2OH
CH2OH
O
4
1
OH
O
OH
OH
(b) Starch: 1– 4 linkage of  glucose monomers
OH
CH2OH
O
HO
O
OH
1
OH
O
O
OH
CH2OH
OH
O
O
OH
Figure 5.7 A–C
4
OH
CH2OH
O
OH
(c) Cellulose: 1– 4 linkage of  glucose monomers
CH2OH
OH
Structural Polysaccharides
Cellulose- a chain of glucose
molecules in which the monomers
alternate positions.
Similar to amylose but not recognized
by the same enzymes.
A water-tight, structural molecule.
Plant cell walls
Cellulose- A Structural
Polysaccharide of Plants
A major component of the tough walls
that enclose plant cells
Cellulose microfibrils
in a plant cell wall
Cell walls
Microfibril
About 80 cellulose
molecules associate
to form a microfibril, the
main architectural unit
of the plant cell wall.
0.5 m
Plant cells
Parallel cellulose molecules are
held together by hydrogen
bonds between hydroxyl
groups attached to carbon
atoms 3 and 6.
Figure 5.8
OH CH2OH
OH
CH2OH
O O
O O
OH
OH
OH
OH
O
O O
O O
O CH OH
OH
CH2OH
2
H
CH2OH
OH CH2OH
OH
O O
O O
OH
OH
OH
OH
O
O
O O
O
O CH OH
OH CH2OH
2
H
CH2OH
OH
OH CH2OH
O O
O O
OH
OH
OH
OH O
O
O O
O
O CH OH
OH
CH2OH
2
H
 Glucose
monomer
Cellulose
molecules
A cellulose molecule
is an unbranched 
glucose polymer.
Cellulose is difficult to digest:
 Cows have microbes in their
stomachs to facilitate this process
(relationship?).
Figure 5.9
Polysaccharides and Clean Hair!
Chitin, another important structural
polysaccharide


Is found in the exoskeleton of arthropods.
Can be used as surgical thread.
CH2O
H
O OH
H
H
OH H
OH
H
H
NH
C
O
CH3
(a) The structure of the
chitin monomer.
Figure 5.10 A–C
(b) Chitin forms the exoskeleton
of arthropods. This cicada
is molting, shedding its old
exoskeleton and emerging
in adult form.
(c) Chitin is used to make a
strong and flexible surgical
thread that decomposes after
the wound or incision heals.
3. Chitin
Structural polysaccharide of Arthropods
(insects and crustaceans) and fungi.
Modified form of cellulose; has an added
nitrogen group to each glucose unit.
Hard, flexible, and water-tight.
Few organisms can digest.
Exoskeleton of Arthropods.
Polysaccharide?
Lipids
Have C, H, O, but more H and less O
than carbohydrates.
Four Kinds: Fats, Phospholipids,
Terpenes, Steroids
Functions of Lipids: 1. May form
cell membranes. 2. Used for longterm energy storage.
Does the Cell Make Me Look Fat?
Stored Fat
Nucleus
1. Fats
A Fat = Glycerol + 1 or more Fatty Acids
Glycerol- a 3 carbon alcohol.
Fatty Acid- HO - C – R
O
Where R = hydrocarbon chain.
Synthesis of a Fat
Dehydration Synthesis removing H2O and forming an
ester bond between the OH of
glycerol and the carboxyl group
of a fatty acid.
Fats: are constructed from two
types of smaller molecules, a
single glycerol and usually three
fatty acids.
H
H
C
O
C
OH
HO
H
C
OH
H
C
OH
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
Fatty acid
(palmitic acid)
H
Glycerol
(a) Dehydration reaction in the synthesis of a fat
Ester linkage
O
H
H
C
O
C
H
C
H
O
H
C
O
C
O
H
C
H
Figure 5.11
O
C
H
C
H
H
C
H
C
H
H
H
C
H
C
H
H
H
C
H
H
C
H
H
C
H
H
C
H
C
H
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
(b) Fat molecule (triacylglycerol)
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
H
C
C
H
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
C
H
H
H
C
H
H
H
C
H
H
H
C
H
H
A Glycerol
Three Fatty
Acids
Types of Fatty Acids
Saturated Fatty Acids- single-bonded
hydrocarbon chains completely filled with
H. Solids at Room Temp. Usually from
animals. Ex. Lard
Unsaturated Fatty Acids- usually contain
a double bond within the hydrocarbon
chain, at least one carbon may bond with
a H. Liquids at room temp. Derived from
plants. Ex. Veg. Oil
Saturated Fatty Acids:
-have the maximum number of hydrogen
atoms possible.
-have no double bonds.
Stearic acid
Figure 5.12 (a)
Saturated fat and fatty acid
Unsaturated Fatty Acids:

Have one or more double bonds.
Oleic acid
Figure 5.12
(b) Unsaturated fat and fatty acid
cis double bond
causes bending
So what is Peanut Butter? If it
comes from a plant, it should be
a(n)….
Unsaturated Fat! But it’s a solid!
It is a hydrogenated fat!
The Importance of Fats
Efficient energy-storage molecules
because of high # of C-H bonds. More
than twice the # in carbs.
Convert unused glucose into starch or
fats.
Fats = 9 kcal/g; Carb = 4 kcal/g
Energy in Saturated fats > Unsaturated
fats
2. Phospholipids
Substitute a phosphate (PO4) for one
fatty acid in a triglyceride.
The (PO4) group is polar (charged).
The polar ends interact with each otherHydrophilic
The nonpolar (uncharged) hydrocarbon
chains interact- Hydrophobic
Found in all cell membranes.
Phospholipid structure:

Consists of a hydrophilic “head” and
hydrophobic “tails.”
+
N(CH )
CH2
3 3
Choline
CH2
O
O
P
O–
Phosphate
O
CH2
CH
O
O
C
O C
CH2
Glycerol
O
Fatty acids
Hydrophilic
head
Hydrophobic
tails
Figure 5.13
(a) Structural formula
(b) Space-filling model
(c) Phospholipid
symbol
The structure of phospholipids:

Results in a bilayer arrangement found in
cell membranes.
WATER
Hydrophilic
heads
WATER
Hydrophobic
tails
Figure 5.14
3. Terpenes
Long chain lipids; many CH bonds.
Many photosynthetic pigments are
terpenes.
Examples are the cholorophyls and
carotenes.
Rubber is a terpene.
4. Steroids and other ringed lipids
Four-ringed Structures.
Ex. Cholesterol, hormones, vitamin D
Animal cell membranes contain
cholesterol, most bacteria do not.
Lipids are Effective Barriers
At the cellular level – phospholipids.
A waxy covering on the epidermis of
plants – cutin.
Coating of bird wings – oils.
Other

Fats provide a way of absorbing
and storing fat-soluble vitamins A,
D, E, K.
DDT: a fat-soluble poison and the
osprey
Genetics
Basic unit of heredity- Gene- a linear
sequence of nucleotides of DNA.
Genotype- genetic make-up of
organism; its potential characteristics.
Phenotype- the observable physical
traits of an organism.
The Phenotype is the organism’s
physical expression of its Genotype.
Eukaryotes are Diploid
Locus - is a gene’s location on the
chromosome.
Allele- an alternative form of a gene at
a specific locus.
Eukaryotes have pairs of identical
chromosomes- diploid. May have two
alleles of a gene.
Prokaryotes are not diploid.
Mutation
A permanent change in the
sequence of nucleotides mutation. Mutations change the
information of that gene.
DNA- function is to store and
transfer information.
How is DNA Accurately
Transferred?
DNA serves as a template for its own
replication; an exact pattern.
How, you ask?
By base pairing.
What is a Nucleotide?
Subunits of DNA/RNA are
Nucleotides = nitrogenous base +
deoxy- or ribose sugar (5 carbons)
+ PO4
Purines: Adenine and Guanine
Pyrimidines: Cytosine, Thymine,
Uracil
Monosaccharides of
Nucleic Acids
Adenosine Monophosphate
Base = adenine
In DNA, sugar = deoxyribose (In
RNA, sugar = ribose)
A phosphate group, PO4
The Nucleotide = AMP
Adenosine
Monophosphate
Guanosine
Monophosphate
Thymine
Monophosphate
Cytosine
Monophosphate
Uracil Monophosphate (in
RNA)
Base Pairing Rules
In DNA,
A=T
C G
In RNA,
A=U
C G
H-Bonding Between Bases
Characteristics of DNA
Chains of nucleotides linked together by
phosphodiester bonds.
Carbon 5 of deoxyribose is attached to
PO4.
Carbon 3 of deoxyribose is a OH- free to
attach to the next nucleotide.
Double helix is held together by Hbonding.
Double Helix
DNA is antiparallel:
5’PO4 ------------------------3’OH
3’OH ------------------------5’PO4
DNA Replication
Begins at a specific location on the
circular bacterial chromosome-origin
(OriC).
Occurs in two directions at the same
time-two moving replication forkspoints where the two strands separate
to allow replication of DNA.
Replication Fork
DNA Replication
Prokaryotes
Eukaryotes
single, circular
multiple, linear
chromosome.
chromosomes.
one single origin several origins on
on the
each
chromosome.
chromosome.
rate of over 1,000 rate of about 50nt/second.
100 nt/second