Transcript AMacromolecules

Chapter 5
The Structure &
Function of
Macromolecules
Slide show modified from Kim Foglia @
http://www.explorebiology.com
Carbon (Organic)Compounds
Organic molecules must have a
Carbon – Carbon bond and
Hydrogen
Carbon
• All known life is based on carbon
• Carbon has 4 electrons in its outer orbit –
therefore there are four available bond sites
C
• It readily bonds to other carbon atoms and
other elements (H,N, O) (S,P)
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
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 carboxyl group is #1
Is it D or L ?
Isomers
• 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.
• Most naturally occurring sugars are D isomers.
• D & L sugars are mirror images with same name.
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
POLYSACCHARIDES~ “many sugars”
http://www.district87.org/biology87/apbio/biochem/Activity6_notes.pdf
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
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).
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.
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
Deoxyribonucleic acid (DNA)
Complementary strands
H bonds ~ between paired bases
van der Waals ~ between stacked bases
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
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.
NUCLEOTIDES can transfer and
store energy
Adenosine triphosphate (ATP)
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)
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
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
Quaternary Structure
• Conformation:
2 or more polypeptide
chains aggregated into
one macromolecule
√ collagen
(connective tissue)
√ hemoglobin
WHAT DO PROTEINS DO?
* See page 78 in Campbell for other examples
http://www.biologie.uni-hamburg.de/b-online/library/cat-removed/enzyme_.gif
ENZYMES
Enzymes are protein catalysts
that accelerate chemical reactions
in living things
Enzymes reduce activation energy
required for reaction
Enzymes are specific and fit
substrate like a lock and key.
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
• pH
• Salt concentration
• Temperature
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.
NUCLEIC ACIDS