Transcript Macromolecules

Unit 1: Cellular Energetics
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Part I – Macromolecules
Part II – Enzymes
Part III – Cellular Respiration
Part IV – DNA Replication
Part V – Protein Synthesis
Part I – Macromolecules
The questions:
• What are monomers? What are polymers?
• How are polymers synthesized (built) and
hydrolyzed (broken down)?
Dehydration Synthesis
(condensation)
– Reaction that joins molecules together by removing
water
– Polymerization = the synthesis of a polymer
– Polymers are built from monomers via dehydration
synthesis
Hydrolysis
• Breaks polymers into their constituent
monomers (“building blocks”) by lysing
(breaking) bonds through the addition of
water.
1. Carbohydrates (polysaccharides)
• Contain CHO
• General molecular formula = CH2O
• Aldoses and Ketoses vary in location of carbonyl
group -C=O
– Aldoses have carbonyl on ends (glucose)
– Ketoses have carbonyl within molecule (fructose)
Monomer = monosaccharide
Disaccharides (double sugars)
• 2 monosaccharides joined by a glycosidic linkage
– Covalent bond formed between two monosaccharides
by dehydration synthesis
Examples of disaccharides
• Maltose = glucose + glucose
• Sucrose = glucose + fructose
• Lactose = glucose + galactose
Polysaccharides (many sugars)
• Long polymers of many monosaccharides
• Architecture & function determined by
position of glycosidic linkages
– Alpha linkages are breakable by Eukaryotes
• Starch, glycogen
– Beta linkages are NOT
• Cellulose, chitin
Types of Polysaccharides
A. Structural polysaccharides:
– Beta glycosidic linkages
– Cellulose - plant cell walls, structural molecule
– Chitin - exoskeleton in insects, arachnids,
crustaceans
B. Food storage molecules
– Alpha glycosidic linkages
– Starch- food storage molecules in plants
– Glycogen- food storage molecules in animals
2. Lipids
• Group shares one common trait – no affinity for
water
• Do NOT consist of monomers → polymers
• Highly varied group
• Biologically important:
– Fats
– Phospholipids
– Steriods
A. Fats
• Made of glycerol and 3 fatty acids
• Saturated fatty acids (animal fats) are carbon
chains with single bonds only
– Ex: Butter, lard; solids at room temp.
• Unsaturated fatty acids (plant fats) have at least
one double bond (kinks in chain)
– Monounsaturated = only one double bond
– Polyunsaturated = many double bonds
• Ex: Vegetable oils; liquid at room temp
“Hydrogenated” fatty acids
• Hydrogen is artificially added to replace
double bonds with single bonds.
• Liquids are solidified
• Ex: peanut butter, margarine
B. Phospholipids
• 2 fatty acids (tails)
attached to phosphate
group “head”
• When placed in water
they self assemble into
a micelle
C. Steroids
• Lipids characterized by carbon skeletons
consisting of four fused rings
• Ex. Cholesterol
– Common component of animal cell membranes (this
is why animal meat is higher in cholesterol)
– Precursor from which other steroids, including sex
hormones, are synthesized
3. Proteins
• Most diverse of all macromolecules
• Humans have over twenty thousand proteins in
their bodies, each performing a specific
function
General Categories of Proteins
1) Structural: Spider silk
2) Storage : Egg white
3) Transport: Hemoglobin
4) Hormonal: Insulin
5) Receptor: Transport protein
6) Contractile: Actin & myosin
7) Defensive: Antibodies
8) Enzymatic: Digestive enzymes
Monomers = Amino Acids
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20 total amino acids
8 “essential” AA’s; must be derived from food
12 can be synthesized by body
THREE TYPES
– Non-polar (8)
– Polar (7)
– Electrically charged (acidic, basic) (5)
General structure of amino acid
• All amino acids have a carboxyl group (-COOH)
on one end and an amino group (NH3) on the other
• R group determines their interactions with one
another to form secondary, tertiary, and quaternary
structure
Polymers = polypeptides
• Formed by dehydration synthesis
• Peptide bonds: bonds between adjacent amino
acids
Protein shape determines function
• Primary structure: sequence of amino acids
• Secondary Structure: coiling or folding of
polypeptide chain in repeated patterns
– Ex: Alpha helices
– Ex: Beta pleated sheets
• Tertiary structure: irregular contortions from
interactions between side chains (R-groups)
with one another
– H-bonds
– Disulfide bridges
– Hydrophobic interactions
• Quaternary structure: 2 or more polypeptide
chains aggregated into 1 functional molecule
4. Nucleic Acids
• Nucleic acids are the building blocks of
both DNA and RNA
– DNA directs its own replication, transmits
genetic information to future offspring, and
controls RNA synthesis
– RNA controls protein synthesis
Nucleotides
Monomer = Nucleotides
• Nucleotide - building block of nucleic acids
• Composed of three subunits:
1) Pentose sugar (ribose or deoxyribose)
2) Phosphate groups comprise the “sugarphosphate” backbone
3) Nitrogenous bases = variable portions of the
molecule
DNA vs. RNA
Polymer = polynucleotide
• Adjacent nucleotides are
joined by covalent bonds
called phosphodiester
linkages between the -OH
on one nucleotide and the
phosphate on the next
nucleotide
Complementary Base Pairing
• Always a Pyrimidine with a Purine
– Purines are Adenine & Guanine
– Pyrimidines are Cytosine, Thymine (DNA only),
and Uracil (RNA only)
Complementary Base Pairing
Why Do Bases Bond This Way?
• Hydrogen bonds:
– A and T form two hydrogen bonds
– G and C form three hydrogen bonds
• Therefore, there is no way to bond inappropriately
Base Pairing
T
A
G
Base Pairing
C
Macro Structure of DNA
• Double Helix- “Twisted Ladder” of A-T and G-C
base pairing
• DNA contains genes (thousands) that code for
proteins
• In association with proteins (histones) DNA
makes chromosomes (46 in humans)
• Stored in nuclei of Eukaryotic cells