Chapter 5
The Structure &
Function of
Macromolecules
Slide show modified from Kim Foglia @
http://www.explorebiology.com
4 MAJOR MACROMOLECULES
• Carbohydrates
• Lipids
• Proteins
• Nucleic acids
POLYMERS
Large molecule made by linking
smaller subunits together
– Monomers (small subunits)
– Covalent bonds
Image by Riedell
SEE AN
ANIMATION
SEE AN
ANIMATION
CARBOHYDRATES
http://www.graphic-design.com/Type/sugar/index.html
http://www.ifr.ac.uk/SPM/images/Starch%20products.jpg
MONOSACCHARIDES
Simple sugar molecules
Composed of C,H,O (CH2O)n
3-7 carbons
Name often ends in –ose
C6H12O6
http://www.cybercolloids.net/library/sugars/glyceraldehyde.gif
http://www.estrellamountain.edu/faculty/farabee/biobk/BioBookCHEM2.html
http://217.60.75.10/llt/biokemi/images/galactose.jpg
http://217.60.75.10/llt/biokemi/images/galactose.jpg
http://www.estrellamountain.edu/faculty/farabee/biobk/BioBookCHEM2.html
D-glyceraldehyde
C3H6O3
C5H10O5
NUMBERING
• Carbons are numbered
• Carbon with carbonyl group is #1
Is it D or L ?
• For sugars with more than one chiral center, the D or L
designation refers to the asymmetric carbon farthest
from the aldehyde or keto group.
• D=”dextro” or DEXTROROTATORY Latin for right;
L=Levo,or LEVOROTATORY.. Latin for “sinister or
Left”. Indicates that the molecule will rotate polarized
light of specific wavelength to right or left.
• Most naturally occurring sugars are D isomers. (WHY?)
• D & L sugars are mirror images with same name.
Pentoses and
hexoses can
cyclize
in water
See animation
• Carbons can be numbered
• Carbon with carbonyl group is #1
CARBOHYDRATES SUPPLY ENERGY
Cells burn glucose and store the
energy released as ATP
Images from: http://www.miranda.com/library.en/Images/Pictures/girls-runners.jpg
http://www.estrellamountain.edu/faculty/farabee/biobk/BioBookCHEM2.html
Disaccharides
• Use dehydration synthesis to join TWO
sugar molecules
• covalent bond between 2 monosaccharides
= GLYCOSIDIC linkage
EX: Sucrose (table sugar)
• most common disaccharide
http://faculty.clintoncc.suny.edu/faculty/michael.gregory/files/Bio%20101/Bio%20101%20Lectures/Biochemistry/bioche1.gif
http://www.biotech.iastate.edu/lab_protocols/HSSB-TLC_images/sucrose.gif
DISACCHARIDES
Glucose + Fructose → Sucrose + H20
Glucose + Glucose → Maltose + H20
Glucose + Galactose → Lactose + H20
http://www.district87.org/biology87/apbio/biochem/Activity6_notes.pdf
POLYSACCHARIDES~ “many sugars”
Ex: STARCH
• polymer of αlpha glucose
• linked by α 1-4 glycosidic linkages
Function:
Energy storage in PLANTS
Most animals have the enzymes to hydrolyze
starch, too
http://www.langara.bc.ca/biology/mario/Assets/Amylopectin.jpg
POLYSACCHARIDES~ “many sugars”
TWO KINDS OF STARCH:
amylose = unbranched starch
amylopectin = branched starch
http://www.langara.bc.ca/biology/mario/Assets/Amylopectin.jpg
POLYSACCHARIDES~ “many sugars”
EX: GLYCOGEN
alpha 1-4 glycosidic bonds like starch
More branched than amylopectin
FUNCTION:
Energy storage in ANIMALS
Stored in liver and
muscle tissue
http://www.abcbodybuilding.com/magazine04/scientific.htm
POLYSACCHARIDES~ “many sugars”
FUNCTION: Structural
PLANTS ~ CELLULOSE
Major component in cell walls
Most abundant organic compound on Earth
beta (ß) 1-4 glycosidic linkages
• Enzymes that digest starch by hydrolyzing alpha linkages
can’t hydrolyze beta linkages in cellulose
• Cellulose in human food passes through the digestive
tract as insoluble fiber
• Some microbes use enzymes to digest cellulose
• Many herbivores, from cows to termites, have symbiotic
relationships with these microbes
POLYSACCHARIDES
FUNCTION: Structural
EX: CHITIN
Structural polysaccharide made from ß glucose
with a NITROGEN containing group attached
Major component of:
Exoskeletons in Arthropods
Cell walls in Fungi
Dissolvable surgical thread
FATTY ACIDS USED CAN :
•
•
•
•
Be same or different in one molecule
Vary in length
Vary in number/location of double bonds
Saturated (single bonds)
vs. unsaturated fats (double bonds)
Kink in chain wherever
a cis double bond
occurs
FATS
LONG HC chain
• NON-POLAR
• HYDROPHOBIC
FUNCTION:
•Energy storage
very rich
2X energy in carbos
•Cushions organs
•Insulates body
Think whale blubber!
Lipids, II
Phospholipids
HEAD (PHILIC)
Glycerol
Phosphate group-PO4Negative charge
TAILS (PHOBIC)
2 fatty acids
instead of 3
SEE A
MOVIE !
PROTEINS
http://images.foodnetwork.com/webfood/images/gethealthy/nutritionalallstars/LeanProteins_header.jpg
PROTEINS ARE MADE FROM AMINO ACID
SUBUITS
• Structure
– Central carbon
– Amino group
– Carboxyl group
– R group (side chain)
• Variable group
• Confers unique chemical properties
• polar (hydrophilic), nonpolar (hydrophobic), acid
or base
• Join via DEHYDRATION SYNTHESIS
reactions
R GROUPS
Each kind of amino acid has a different R group
20 different amino acids are used by cells to make
proteins
(There are a few other aa’s, but rare)
See an
animation
POLYPEPTIDES
• POLYMERS
OF AMINO ACIDS
ARE CALLED POLYPEPTIDES
•DNA determines the amino acid
sequence
http://www.emc.maricopa.edu/faculty/farabee/BIOBK/BioBookCHEM2.html
http://www.cherishedtimedesigns.com/images/BaliCharmBraceletGraduation500.jpg
A functional PROTEIN is not just the
polypeptide chain.
A PROTEIN consists
of one or more
polypeptide chains
twisted, folded,
and coiled into a
unique molecular shape
What determines the shape?
Image from:
http://www.tvdsb.on.ca/saunders/courses/online/SBI3C/Cells/Protein-Structure03.jpg
SEE AN
ANIMATION
pH effects the charge and
reactivity of amino acids
PROTEIN STRUCTURE & FUNCTION
Function depends on structure
• 4 levels of organization
• result in 3-D structure
Primary Structure
Amino acid substitution:
in hemoglobin code
sickle-cell anemia
A
T
Secondary Structure
folding along short sections
• Due to:
R group interactions
(phobic/philic)
• Alpha Helix:
coiling;
• ß Pleated Sheet:
parallel;
• Hydrogen bonds
between adjacent
amino acids
hold shape
Tertiary Structure
interactions between side chains
Conformation:
irregular contortions
from R group bonding
√ hydrophobic
√ disulfide bridges
√ hydrogen bonds
√ ionic bonds
Functional Groups
• Sulfhydral Group
• Called: thiols
•
http://www.mun.ca/biology/scarr/Disulfide_bridge.htm
DISULFIDE BRIDGES
BETWEEN nearby
CYSTEINE amino acids
(Notice name change
when bonded)
STABLIZE 3-D
SHAPE
http://sandwalk.blogspot.com/2007/02/disulfide-bridges-stabilize-folded.html
Quaternary Structure
• Conformation:
2 or more polypeptide
chains aggregated into
one macromolecule
√ collagen
(connective tissue)
√ hemoglobin
See an
animation
WHAT DO PROTEINS DO?
* See page 78 in Campbell for other examples
ENZYMES
http://www.biologie.uni-hamburg.de/b-online/library/cat-removed/enzyme_.gif
Enzymes are protein catalysts
that accelerate chemical reactions
in living things
SEE ANIMATION
of AMYLASE
Enzymes reduce activation energy
required for reaction
Enzymes are specific and fit
substrate like a lock and key.
LEARN MORE
Enzymes are not changed
by reaction and are reusable.
http://www.grand-illusions.com/images/articles/toyshop/trick_lock/mainimage.jpg
PROTEIN CONFORMATION ALSO
DEPENDS ON PHYSICAL
ENVIRONMENT
LEARN MORE
• pH
• Salt concentration
• Temperature
See a movie
Choose narrated
http://www.nealbrownstudio.com/adm/photo/163_nb_fried_egg.jpg
http://www.desktopfotos.de/Downloads/melt_cd.jpg
Proteins that have denatured are
biologically inactive
Once conditions change, protein
may need help returning to its
functional shape.
Facilitation of
folding
NUCLEIC ACIDS
Nucleic Acids
The main functions of nucleotides are:
information storage (DNA),
protein synthesis (RNA)
energy transfers (ATP and NAD).
Nucleic Acids
Nucleic acids are polymers composed
of units known as nucleotides.
The main functions of nucleotides are:
information storage (DNA),
protein synthesis (RNA)
energy transfers (ATP and NAD).
Nucleic Acids
Nucleic acids are polymers composed of
units known as nucleotides.
Nucleotides consist of a pentose (5C)
sugar, a nitrogenous base, and a
phosphate.
Sugar and phosphate alone = nucleoside
Nucleic Acids
The sugars are either:
OR
deoxyribose
ribose
Nucleic Acids
Nitrogeneous bases can be:
Purines (Adenine and Guanine) ~ double-ring
Pyrimidines (Cytosine, Thymine and Uracil)
~ single-ring
Deoxyribonucleic acid (DNA)
Nitrogen base attached to sugar
at C-1
Phosphate attached to sugar
at C-5
Phosphate attached to next
nucleoside at C-1 by
phosphodiester linkage
Each strand has a 3’ and 5’ end
http://staff.um.edu.mt/acus1/3Molgen.htm
DNA
Deoxyribonucleic
acid (DNA) is the
physical carrier of
inheritance for 99%
of living organisms.
Image from: http://sbchem.sunysb.edu/msl/dna.gif
Deoxyribonucleic acid (DNA)
Deoxyribose sugar
Nitrogeneous bases:
A, C, G and T
• DOUBLE HELIX
• sugar & phosphates make
up sides of ladder
• nitrogen bases form steps
Deoxyribonucleic acid (DNA)
Strands run antiparallel
http://www.biology.arizona.edu/biochemistry/problem_sets/large_molecules/06t.html
Deoxyribonucleic acid (DNA)
Complementary strands
H bonds ~ between paired bases
van der Waals ~ between stacked bases
http://staff.um.edu.mt/acus1/3Molgen.htm
Nucleic Acids
• Inheritance based on
DNA replication
• Double helix
(Watson & Crick - 1953)
• Based on Rosalind Franklin’s
Xray crystallograpy
Ribonucleic acid (RNA)
Ribose sugar
Nitrogeneous bases:
A, C, G, and U
SINGLE STRANDED
http://www.biology.arizona.edu/biochemistry/problem_sets/large_molecules/06t.html
RNA
RNA functions in protein synthesis.
There are three types of RNA:
Messenger RNA (mRNA)
~ blueprint for construction of a protein.
Ribosomal RNA (rRNA)
~ construction site where the protein is made.
Transfer RNA (tRNA)
~ truck delivering the proper amino acid to the site
at the right time.
Deoxyribonucleic acid (DNA)
Ribonucleic acid (RNA)
DNA → RNA → protein
NUCLEOTIDES can transfer and
store energy
Adenosine triphosphate (ATP)
NUCLEOTIDES can transfer and
store energy
NAD+
NADP+
FAD
Coenzyme A
Energy and electron carriers
used in photosynthesis and
respiration
More on this next unit!