Transcript Macromolecules

Macromolecules
The Molecules of Life!
Most macromolecules are polymers
Monomer
Polymer
Macromolecule
Polymerization Reactions
Chemical
reactions that
link two or more small
molecules to form larger
molecules
Condensation Reactions
 Also
known as dehydration
synthesis
 Monomers are linked covalently
producing a net removal of water.
 One monomer loses an H the
other an OH or hydroxyl.
 Requires energy and enzymes
Hydrolysis
breaking”
 A reaction that breaks the
covalent bonds between
monomers by the addition of
water molecules

“Water
Structural variation
 Structural
variation of macromolecules is the basis for the
enormous diversity of life.
 Unity= only about 40-50 monomers
 Diversity- new properties emerge as
various monomers are put together
Carbohydrates
 Quick
energy
 Made from monomers called
monosaccharide
 Classified on the number of
simple sugars
Monosaccharide
Simple sugars

Ratio = CH2O
nutrients for cell –glucose
 Can be made by the sun
Photosynthesis
 Energy stored in their chemical bonds
which are broken in cell respiration
 Carbon skeletons used for other
organic molecules.
 Major
Characteristics of sugar
 An
OH- group is attached to
each carbon except one which is
double bonded to a carbonyl
 Size of skeleton varies 3 to 7
carbons
 Spatial arrangements vary
3 Monosaccharide
 Glucose
 Fructose
 Galactose
Disaccharides
sugar”
 Two monosaccharides joined by
a GLYCOSIDIC linkage.
 A covalent bond between two
sugar monomers resulting from
a condensation reaction.

“Double
Examples of Disacchrides
 Maltose
glucose + glucose=
malt sugar
 Lactose glucose + galactose=
milk sugar
 Sucrose glucose + fructose=
fruit sugar
Polysacchrides
 Macromolecules
that are polymers
of a few hundred or thousand
monosaccharides
 2 important biological functions
 Energy storage- starch/glycogen
 Structural support- cellulose/chitin
Starch
Energy storage for plants
 Helical glucose polymer with alpha
helix 1-4 glycosidic linkages.
 Stored in plastids
 Amylose- simplest form
 Most animals can digest

Glycogen
Storage
polysaccharide in
animals
Stored in the muscle and
live of humans and other
vertebrates
Structural Polysaccharides
Cellulose- Linear unbranched polymer of
D-glucose in Beta 1-4 linkages.
 Major component of cell walls/ reinforces
 Different from starch in its glycosidic
linkages! (important!)
 Cannot be digested by most organisms.
 Exception- some bacteria, fungi.

Chitin
 A polymer
of
an amino
sugar
 Forms
exoskeletons
of arthropods
Lipids
 Fats,
Phospholipids and Sterols
 Insoluble in water but will
dissolve in nonpolar solvents like
ether, chloroform benzene
FATS composed of C,H,O
Macromolecules made from:
 1. Glycerol- a 3-carbon alcohol


2. Fatty Acid (carboxylic acid)
A carboxyl group at one end and a
attached (non polar) hydrocarbon tail
Ester Linkage
 Bond
formed between a hydroxyl
group (OH-) and a carboxyl group
(-COOH)
 Triacylglycerol- a fat composed of
three fatty acids bonded to one
glycerol by 3 ester linkages.
 SEE BOOK for pictures!!!
Characteristics of fat
 Insoluble
in water due to long fatty
acid chains which have lots of
nonpolar C-H bonds
 Vary by fatty acid composition,
length, and location of Carbon to
Carbon bonds.
Saturated Fat
 No
double bonds, Carbon bonded
to maximum # of hydrogen's
 Solid at room temp
 Most animal fats
Unsaturated Fats
 One
or more double bonds
between carbons in fatty acid tail
 Tail kinks at each C=C so
molecules do not pack close
enough to solidify.
 Liquid, plant fats
Why is Fat important?
 Energy
storage- 1 gram of fat has
2x the energy as a gram of
polysaccharide
 More compact fuel reservoir than
a carbohydrate
 Cushions vital organs
 Insulates against heat loss
Phospholipids
Compound make up of a glycerol, two
fatty acids and a phosphate

The head is hydrophilic

The tails are hydrophobic

Importance of Phospholipids
 Major
constituents of cell
membranes. Because
phospholipids are ambivalent
towards water. they are able
to form a type of barrier
around the cell’s cytoplasm.
Steroids
 Lipids
which have four
fused carbon rings
with various functional
groups attached.

See picture in book
Cholesterol- an important steroid
Precursor to many other steroid including
 Vertebrate sex hormones
 Has an important role in the keeping the
cell membrane fluid
 Overproduction and over consumption
can contribute to atherosclerosis

Proteins
Composed of Carbon,
 Hydrogen, Oxygen
 And Nitrogen

Proteins are building blocks
The monomers are amino acids.
 There are 20 amino acids which form a
huge variety of proteins
 Polypeptide chains- polymers of amino
acids arranged in a specific linear
sequence and linked by peptide bonds.

Protein
 A macromolecule
that consists
of one or more polypeptide
chains folded and coiled into
specific conformations.
 Each kind has its own unique 3D shape
Importance of Proteins








Structural support (collagen)
Storage (of amino acids)
Transport (hemoglobin)
Signaling (Chemical messengers)
Cellular response to chemical stimuli
Movement (contractile proteins)
Defense (antibodies)
Catalysis of Biochemical reactions Enzmyes
Amino Acids
Building block of protein
 Most consist of an asymmetric carbon
covalently bonded to:
H O
 Hydrogen atom
H3N+- C
 Carboxyl group
R
O
 Amino group
 Variable R group (side chain)

Unique properties of Amino Acids
A. acids contain both a carboxyl group
and an Amino group. Since one group
acts like a weak acid (carboxyl) (-) the
other acts as a weak base (amine) (+) so
an amino acid can exist in three anion
states.
 Some have polar side groups, some
nonpolar.

Peptide Bond
Covalent Bond formed by a
condensation reaction that links the
carboxyl group of one amino acid to
the amino group of another.
 Has polarity with the –COOH group
on one end and the NH2 group on the
other
 Backbone= N-C-C-N-C-C
A Proteins Shape
3-D unique shape
 Native conformation
 Enables a protein to recognize and bind
specifically to another molecule
 Consequence of linear arrangement of
amino acids, folded and coiled and
stabilized by chemical bonds and weak
interactions.

Four levels of Protein Structure
Primary
Secondary
Tertiary
Quaternary
Primary
 Unique
sequence of amino acids
 (Like beads on a string)
 Pioneer in sequencing- Frederick
Sanger who sequenced insulin in
the late 40’s.
Secondary
Regular repeated coiling and folding of a
protein’s polypeptide backbone
 Contributes to proteins overall
conformation
 Stablized by HYDROGEN bonds
between peptide linkages
 2 Types: Alpha Helix and Beta Pleated
 See book pictures

Tertiary Structure (important!)
Irregular contortions of a protien due to
bonding between side chains ® groups;
third level of protein structure imposed
on primary and secondary structure.
 Covalent linkage( disulfide bridges) and
weak interactions (ionic bonds, hydrogen
bonds and hydrophobic interactions)
contribute to bonding stability.

Quaternary Structure
Structure that results from the
interaction among several polypeptides
in a single protein
 Example: Collagen, Hemoglobin
 See the book for a picture

What determines protein
conformation?
A protein’s 3-D shape is the result of the
interactions responsible for the
secondary and tertiary sturcture
 Influenced by physical and chemical
environmental conditions
 If altered may become DENATURED
and lose its native conformation

Denaturation
A proteins shape can be altered by:
 Transfer to an organic solvent.
 Chemical agents that disrupt hydrogen
bonds, ionic bonds and disulfide bridges
 Excessive heat


Some can return to their original state.
A proteins shape..

Even though the primary structure
determines the proteins conformation,
many other factors affect the final shape
which can not always be determined
ahead of time.
Nucleic Acids
Protein structure is determined by
primary structure which is
determined by GENES- heredity
units that consist of DNA- a type of
nucleic acid
 There are two types: DNA and RNA

DNA characteristics





Contains coded information that programs ALL
cell activity
Contains directions for its own replication
Is copied and passed from one generation to
the next
In eukaryotic cells found primary in the
nucleus
Makes up genes that code for Protein
Synthesis
RNA characteristics
Functions in the actual synthesis of
proteins
 Sits of synthesis are on ribosomes in the
cytoplasm
 Messenger RNA carries the encoded
genetic message from the nucleus to the
cytoplasm
 DNA---RNA---Protein

What makes up a nucleic acid?
Monomers are nucleotides linked
together by condensation synthesis.
 A nucleotide is:
 1. nitrogenous base (A,T,C,G,U)
 2. a five carbon sugar (Pentose)
 3. A phosphate group

The bases
Pyrimidine= nitrogenous base with a sixmembered ring made up of carbon and
nitrogen atoms
 Cytosine, Thymine (DNA), Uracil (RNA)
 Purine- nitrogenous base with a 5membered ring fused to a six-membered
ring:
 Adenine and Guanine

Functions of nucleotides
Monomers of nucleic acids
 Transfer energy from one molecule to
another. (ATP)
 Are electron acceptors in enzyme
controlled redox reactions (NAD)

The structure of DNA
Double helix
 Backbone of Sugar and phosphate. The
backbone is the result of phosphodiester
linkages between the phosphate of one
nucleotide and the sugar of the next.
 The sugar is deoxyribose
 The bases in DNA are A,T,C,G

The end………… TEST