Transcript The Structure and Function of Macromolecules
• Macromolecules
nucleic acids.
- larger molecules made from smaller ones.
• 4 major classes of macromolecules: carbohydrates, lipids, proteins, and • 3 of these are polymers because they are made from individual building blocks called monomers.
http://www.diabetes.org.nz/pics/carbohydrate_foods.jpg
• Monomers
- joined together through condensation or
dehydration reaction
(form macromolecules) • Requires energy; uses covalent bonds (links together monomers) • Water produced.
Water produced as by-product
• Hydrolysis
breaks polymers into monomers.
• Water added to polymer; breaks bonds, creates monomers (i.e. digestive process in animals)
• • 1
Carbohydrates Carbohydrates
- sugars (monomers) and polymers.
A
Monosaccharides
sugars.
- simple • B
Disaccharides
- double sugars (monosaccharides linked together) • C
Polysaccharides
- polymers of monosaccharides.
• Sugars named with –ose.
• Monosaccharides needed for cellular work.
• Help to synthesize other macromolecules.
• Maltose - 2 glucose molecules.
• Sucrose - 1 glucose, 1 fructose.
• Polysaccharides
walls.
- energy storage.
• Starch - energy storage polysaccharide for plants.
• Cellulose – polysaccharide; plant cell • Animals store energy as glycogen.
• Chitin - polysaccharide - makes up exoskeleton of arthropods (like crustaceans and our sowbugs!).
Chitin is used in surgery
Lipids • Lipids
• Lipids nonpolar (no affinity for water) • Fat made from glycerol and fatty acids.
- no polymers (exception)
• Saturated fatty acid -
No carbon carbon double bonds in carbohydrate chain. (hydrogen at every possible position) • Form bad fats - solid at room temperature (butter, lard)
No double-double bonds
• unsaturated fatty acid
temperature (oils) - 1+ carbon-carbon double bonds.
• Formed by removal of hydrogen atoms from carbon skeleton.
• Form good fats - liquid at room
• Purpose of fat - energy storage. • Gram of fat stores 2X as much energy as gram of polysaccharide. • Fat also cushions vital organs.
• Layer of fat can also function as insulation.
http://www.healthline.com/blogs/diet_nutrition/uploaded_images/fat-cat-712938.jpg
• MOST IMPORTANT LIPID IN BIOLOGY = Phospholipid • Phospholipids have 2 fatty acids attached to glycerol.
• Fatty acid tails are hydrophobic, phosphate group and attachments form hydrophilic head.
• When phospholipids added to water, self-assemble with hydrophobic tails pointing toward center, hydrophilic heads on outside.
• Phospholipids in cell form bilayer; major component of cell membrane.
Hydrophilic Hydrophobic
Other Lipids • Steroids
- lipids with carbon skeleton consisting of 4 fused carbon rings.
• Cholesterol - component in animal cell membranes and hormones.
Cholesterol
Proteins • Proteins
- support, storage, transport, defenses, and enzymes.
• Made in ribosomes in cell.
• Proteins - amino acids linked together to form polymer.
• 20 different amino acids that can be linked together to form thousands of different proteins.
http://images.foodnetwork.com/webfood/images/gethealthy/nutritionalallstars/LeanProteins_header.jpg
• Amino acids link -
polypeptides
combine to form proteins.
• Amino acids made of hydrogen atom, carboxyl group, amino group, variable R group (or side chain).
• R group makes amino acids different from one another.
• Shape of protein determines function.
• Shapes - 3 dimensional determined by sequence of amino acids.
• Primary structure
of protein linear sequence of amino acids determined by genetics.
• Secondary structure
shapes are usually formed: alpha coils or beta sheets.
- two
• Tertiary structure
determined by interactions among R groups.
• Quarternary structure
- joining of 2+ polypeptide subunits.
• Collagen and hemoglobin examples.
• Protein’s shape can change due to environment.
• pH, temperature, or salinity (salt concentrations) change - protein can
denature
(starts to fall apart) • Some proteins can return to functional shape after denaturation, others cannot.
Nucleic acids
• Amino acid sequence of polypeptide programmed by a gene.
• 2 types of nucleic acids:
ribonucleic acid (RNA) and deoxyribonucleic acid (DNA).
http://www.uic.edu/classes/bios/bios100/lecturesf04am/nucleotides.jpg
• DNA gives information so RNA can create proteins.
• Flow of genetic information - DNA > RNA -> protein.
• Protein synthesis occurs in ribosomes.
• Monomers of nucleic acids -
nucleotides
.
• Nucleotides made up of 3 parts: nitrogen base, five-carbon sugar, and phosphate group.
• Nitrogen bases, rings of carbon and nitrogen, come in 2 types:
purines and pyrimidines.
• Pyrimidines
thymine (T), and uracil (U in RNA only).
- cytosine (C),
• Purines
- adenine (A) and guanine (G).
• Pyrimidines - single six-membered ring; purines - five-membered ring.
http://library.med.utah.edu/NetBiochem/pupyr/pupy3.gif
• In RNA - sugar is ribose; DNA sugar is deoxyribose.
• Difference between sugars is lack of oxygen atom in deoxyribose.
http://members.aol.com/logan20/ribose.gif
• RNA single-stranded - linear shape.
• DNA forms double helix.
• Sugar and phosphate forms backbone of double helix while nitrogen bases form connection between backbones.
• Adenine (A) always pairs with thymine (T) guanine (G) with cytosine (C).
• Due to six and five membered rings – shapes are compatible.
• Two strands are
complementary
.
http://www.emunix.emich.edu/~rwinning/genetics/pics/dna2.gif
• DNA used to show evolutionary similarities between species.
• Two species that appear to be closely-related based on fossil and molecular evidence also more similar in DNA and protein sequences than more distantly related species.