Anderson Spring 2017 College of the Redwoods Biomolecules Anderson Spring 2017 College of the Redwoods

Let’s Review Atoms – made up of protons, neutrons, and electrons that have the properties of a chemical element Molecules – result of chemical bonding between electrons of atoms Macromolecules – large molecules built from smaller molecules Octet Rule – elements can and want to hold 8 electrons in their outermost shells (except the 1st ring holds just 2) Elements are abbreviated by capital letters: C, O, H (sometimes 1 capital and 1 lower case, like Cl)

Biological Macromolecules Large molecules necessary for life Built from smaller organic molecules (organic = contains carbon) 4 major classes of biological macromolecules Carbohydrates (sugars) Lipids (fats/cholesterol) Proteins Nucleic acids (DNA) Mostly carbon-based, but also include hydrogen, oxygen, nitrogen, phosphorus, sulfur, and a few others

Carbon Bonding Remember: Carbon has 6 protons, 6 neutrons, and 6 electrons That means, according to the Octet Rule, that there are 4 electrons in the outermost ring These are called valence electrons Therefore, carbon can form 4 covalent bonds with other atoms/molecules

Simple Carbon Molecules Remember: 1 dash between molecules = 2 electron being shared 2 dashes = 4 electrons are being shared 3 dashes = 6 electrons are being shared

Scientists like shorthand Every corner and end of line = Carbon Carbon can form up to 4 bonds – carbons not bound to other elements are bonded with hydrogen

1. Carbohydrates Provide energy to the body in the form of starch and sugars Represented by the formula (CH2O)n n = number of carbon atoms, n also multiplies H and O The ratio of C:H:O is always 1:2:1 3 subtypes: monosaccharide (1 sugar ring), disaccharide (2 sugar rings) and polysaccharide (multiple sugar rings)

Monosaccharides (monomers of carbohydrates) # carbons range 3 to 6 (trioses, pentoses, and hexoses) Glucose is most common C6H12O6 Notice they all have 6 carbons yet they’re different These are called isomers (same chemical formula, different structurally and chemically)

Why is glucose so important? Photosynthesis 6CO2 6H2O C6H12O6 6O2 light + carbon dioxide water sugar oxygen Cellular Respiration 6CO2 6H2O C6H12O6 6O2 + carbon dioxide water sugar oxygen ATP energy

Disaccharides Dehydration (removal of water) of 2 monosaccharides to covalently bond them together

Common Disaccharides Sucrose – table sugar Lactose – milk sugar Maltose – malt sugar

Polysaccharides Long chain of monosaccharides covalently linked May be branched or unbranched May contain different types of monosaccharides They can be very large molecules

Starch Stored form of sugars in plants – plants make glucose, then store extra as starch, especially roots and seeds Made up of amylose (unbranched) or amylopectin (branched), which are glucose polymers Broken down by enzyme called “amylase” into maltose (glucose disaccharide)

Glycogen, Cellulose and Chitin Glycogen – storage form of glucose in humans and vertebrates Animal equivalent to starch (made of monomers of glucose) Glycogen is broken down into glucose when glucose levels decrease Insulin stimulates the production of glycogen (without insulin, your blood sugar would increase) Cellulose – makes cell walls in plant cells (providing structural support), also made of glucose monomers Cellulose in our digestive system is called dietary fiber, but we can’t actually digest it. Chitin – exoskeleton of arthropods (insects, spiders, crabs)

2. Lipids Hydrophobic (water fearing) non-polar molecules Mostly carbon-carbon and carbon-hydrogen bonds We call these hydrocarbons Functions Long-term energy storage for cells (fats) Insulation from environment (keep animals dry) Building blocks of many hormones Important constituent of plasma membrane of cells Made of fatty acids and glycerol (monomers)

Fats Glycerol Fatty acid tails Fatty acids = monomers Saturated with hydrogen (no double bonds) Each carbon does not have 2 hydrogens, has double bonds Fatty acids = monomers

Phospholipids Major constituent of plasma membranes (phospholipid bilayer) Has both hydrophobic and hydrophilic regions

Steroids 4 linked carbon rings Cholesterol – steroid mainly synthesized in liver and precursor to many hormones Helps to maintain cell membrane structure

3. Proteins One of the most abundant organic molecules in living things Functions of proteins vary from: catalyzing reactions (enzymes) molecule transportation DNA replication hormone signaling and many more What makes the functions and structure of proteins so diverse are the sequence of the 20 chemically different amino acids

Monomers that make up proteins Amino Acids Monomers that make up proteins Each has same fundamental structure: Central Carbon Amino group (NH2) Carboxyl group (COOH) R group - variable To form proteins, amino acids attach to each other by peptide bonds The result of peptide bonds is polypeptide back bone Amino group Carboxyl group

20 Amino Acids

20 Amino Acids Amino Acid 3 Letters 1 Letter Alanine Ala A Arginine Asparagine Asn N Aspartic acid Asp D Cysteine Cys C Glutamic acid Gln Q Glutamine Glu E Glycine Gly G Histidine His H Isoleucine Ile I Amino Acid 3 Letters 1 Letter Leucine Leu L Lysine Lys K Methionine Met M Phenylalanine Phe F Proline Pro P Serine Ser S Thrionine Thr T Tryptophan Trp W Tyrosine Tyr Y Valine Val V

Protein Structure Proteins have different shapes and molecular weights Some are globular, some are fibrous in shape Sequence of amino acids determines the structure, the structure determines the function There’s an estimated 2 million different types of proteins in the human body, all made from just 20 amino acids!

How does a protein get it’s shape? 4 Levels of Protein Structure Primary Secondary Tertiary Quaternary Sequence and number of amino acids

What determines the AA sequence? Genes (DNA) encode for proteins! Any change in gene sequence can alter amino acid sequences Sickle cell anemia Hemoglobin β – protein that binds oxygen in red blood cells Has 600 amino acids in protein sequence ONE amino acid substitution causes red blood cell to form crescent shape

How does a protein get it’s shape? 4 Levels of Protein Structure Primary Secondary Tertiary Quaternary Hydrogen bonding of peptide backbone

How does a protein get it’s shape? 4 Levels of Protein Structure Primary Secondary Tertiary Quaternary 3-D folding due to side chain (R group) interactions

How does a protein get it’s shape? 4 Levels of Protein Structure Primary Secondary Tertiary Quaternary 2+ amino acid chains (called subunits)

Denaturation of Proteins Structure determines function! Changes in temperature, pH, or chemical exposure can change protein shape Denaturation = proteins losing their shape Can be reversible because amino acid sequence hasn’t changed Can be irreversible (can’t refold) which leads to loss of function

4. Nucleic Acids Carry out genetic blueprint of a cell and carry instructions for the function of a cell Two main types: Deoxyribonucleic acid (DNA) Genetic material found in all living organisms Ribonucleic acid (RNA) Involved in protein synthesis Communicator between nucleus of cell and rest of cell DNA and RNA are made up of monomers called nucleotides

Nucleotides 3 Components of Nucleotides Phosphate group Pentose (5-carbon) sugar Nitrogenous base Adenine Thymine Cytosine Guanine Uracil Difference between DNA and RNA is the pentose sugar (and a nitrogenous base)

DNA Backbone

Double Helix Structure of DNA

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