Chapter 2 The Chemistry of Life
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Chapter 2
The Chemistry of Life
The Nature of Matter
What is matter?
Atom The basic unit of matter, the smallest unit of an
element.
How small are atoms? Can we see
them?
What Are The Parts Of An Atom?
An atom consists of 3 subatomic parts!!
Protons +Neutrons
Electrons -
Nucleus(same mass)
Element
A pure substance that consists entirely of one type of atom.
Periodic Table of Elements
Periodic Table of Elements
How do you calculate the number of neutrons????
Lets Talk About Electrons!!!
How do you know how many electrons an atom has?
Where are theses electrons anyway?
Electrons Shells
An atom is considered
stable when their outer shells are
filled to capacity.
Diagraming Atoms
Bohr Diagrams
Chemical Bonds
How atoms interact with each other to form molecules and compounds all depends
on their electrons.
Theses electrons are referred to as valence electrons.
Compounds
Compounds are 2 or more different elements joined together.
NaCl – Table Salt
H2O – Water
CH4 - Methane
C6H12O6 - Glucose
Molecules
• Molecules are formed when two or more atoms join together.
• They are the smallest unit of compounds.
Chemical Bonds
3 types of chemical bonds – Ionic bonds – when one or more electrons
are transferred from one atom to the other.
– Covalent bonds – when electrons are shared between atoms.
– Hydrogen bonds – weak electrical attraction between atoms of opposite charges
Ionic Bond – electrons are transferred
Chloride IonSodium Ion
“You Complete Me….”
Carbon, oh so lonely…… Hydrogen, if I only had one more electron I would feel
complete!
I feel like we are really bonding! You complete me!
Covalent Bond – electrons are shared
A molecule of water, H20
A molecule of methane, CH4
Water is Weird and It Is Everywhere!
Water is Polar
Water likes to stick together….
Hydrogen Bonds!!!
Cohesion – Surface Tension
Attraction between molecules
of the same substance
Adhesion – Capillary Action
Attraction between molecules of different
substances.
Solutions and Suspensions
Mixture – material composed of two or more elements or compounds that are physically mixed together, but NOT chemically combined.
Solutions and Suspensions
Solution – a mixture of two or more substances where the molecules are evenly distributed.
Solute (salt)
Solvent (water)
When Salt Dissolves in Water
Water Molecule
Water is considered the “UNIVERSAL SOLVENT”,
dissolving other polar and ionic
compounds
Acids, Bases and pH
H2O (H+) + (OH-)
Water (hydrogen ion) + (hydroxide ion)
A water molecule can react to form ions.
pH Scale
Indicates the concentration of H+ ions in solution.
Acids, Bases and pH
Acid – any compound that forms (H+) ions in solution.
Base – any compound that produces (OH-) ion in solution.
Buffers – weak acids or bases that can react with strong acids or bases to prevent sharp, sudden changes in pH.
EXIT PASS
Please write a paragraph that explains how the concentration
of hydrogen ion (H+) determines the acid-base properties of a
solution.
Chemistry of Life
There are 92 naturally occurring elements and of those 92 elements, 25 are essential to life! Some are required in large amounts
while some only in trace (small) amounts.
The six that you must know are
CHNOPS
Without these life would not be possible!!
Carbon Chemistry
Chemistry of Carbon - Organic chemistry is the study of all compounds that contain bonds between carbon
atoms.
The most versatile element!
Carbon Chemistry
Carbon is a versatile atom.
• It has four electrons in an outer shell that holds eight electrons.
• Carbon can share its electrons with other atoms to form up to four covalent bonds.
Carbon CompoundsCarbon can form single, double or triple bonds with other elements. Each line represents 1 covalent bond (2 electrons).
methane
acetylene benzene
• The simplest organic compounds are hydrocarbons, which contain only carbon and hydrogen atoms.
• The simplest hydrocarbon is methane, a single carbon atom bonded to four hydrogen atoms.
Carbon Chemistry
• Larger hydrocarbons form fuels for engines.
• Hydrocarbons of fat molecules are important fuels for our bodies.
Carbon Chemistry
C8H18
CH3(CH2)16CO2H
Giant Molecules from Smaller Building Blocks
• Many of life’s molecules are gigantic, earning the name macromolecules.
• macro = long or large (Greek)
• We, and every living thing is made up of macromolecules. They are vital molecules for our bodies to function properly.
• The four categories of macromolecules are
• Carbohydrates
• Proteins
• Nucleic acids
• Lipids
• Most macromolecules are polymers.
• Polymers are made by stringing together many smaller molecules called monomers.
Giant Molecules from Smaller Building Blocks
H2O
OH H
A dehydration reaction• links two monomers together and
• removes a molecule of water
• Organisms also have to break down macromolecules.
• Digestion breaks down macromolecules to make monomers available to your cells.
Giant Molecules from Smaller Building Blocks
• Hydrolysis
– breaks bonds between monomers
– adds a molecule of water
– reverses the dehydration reaction.
Giant Molecules from Smaller Building Blocks
There are 4 groups of macromolecules
1.Carbohydrates
2.Lipids
3.Proteins
4.Nucleic Acids
Carbohydrates
Carbohydrates are made up of carbon, hydrogen and oxygen in a ratio of 1:2:1.
Living things use carbohydrates their main source of energy.
Carbohydrates
Plants and some animals also use carbohydrates for structural purposes.
Carbohydrates
Glucose monomer
Carbohydrates
3 types of carbohydrates
• Monosaccharides
• Disaccharides
• Polysaccharides
Monosaccharides
• Monosaccharides
• simple sugars that cannot be broken down by hydrolysis into smaller sugars
• the monomers of carbohydrates.
• Common examples
• glucose in sports drinks
• fructose found in fruit.
Disaccharides
Disaccharide• a double sugar
• constructed from two monosaccharides
• formed by polymerization or dehydration reaction.
(C12H22O11)3
Galactose
H2O
OH H
Glucose
Lactose
• Disaccharides include• lactose in milk
• sucrose in table sugar
Disaccharides
•Monosaccharide
•Disaccharide
Polysaccharides
• Polysaccharides
• complex carbohydrates
• made of long chains of sugar units—polymers of monosaccharides.
3 Types of Polysaccharides
Polysaccharides• Starch
•Glycogen
• Cellulose
Starch
• is a familiar example of a polysaccharide
• is used by plant cells to store energy
• consists of long strings of glucose monomers.
• Potatoes and grains are major sources of starch in our diet.
Polysaccharides
Glycogen• used by animals cells to store energy
• converted to glucose when it is needed
• stored in the liver and in muscle cells
Polysaccharides
Cellulose• is the most abundant organic compound on Earth
• cannot be broken apart by most animals.
Polysaccharides
Lipids
Common Categories = Fats, Oils, Waxes, and Steroids
They are hydrophobic, they don’t dissolve in water!!
LipidsMade mostly from carbon and hydrogen with very little oxygen = C, H, O.
Used to
• store energy (fats and oils)
• play important roles in biological membranes (steroids)
• waterproof covering (waxes)
• serve as chemical messengers (steroids).
Fats perform essential functions in the human body including• energy storage – more energy in fat than in carbs!
• cushioning
• insulation
• plasma membrane of cells – phospholipid bilayer
Fats
Lipids (Fats)
Lipids (fats) - saturated
Lipids (fats) - unsaturated
Fats
Figure 3.12a
Saturated Fats
Figure 3.12b
Omega-3 fatsTrans fatsPlant oils
Margarine
Unsaturated Fats
Question!!!Which molecule below represents a Lipid?
a. b.
c. d.
Nucleic Acids
Nucleic acids store and transmit hereditary, or genetic information.
Nucleic acids are polymers made up of monomers called nucleotides.
There are 2 types of Nucleic Acids
• deoxyribonucleic acid (DNA)
• ribonucleic acid (RNA)
Nucleic Acids
Nucleotides are made out of C,H,N,O, and P, and they contain three parts:
• a 5-carbon sugar
• a phosphate group
• a nitrogenous base
Monomer of nucleic acid
Figure 3.23a
Nitrogenous base(A, G, C, or T)
Thymine (T)
Phosphategroup
Sugar(deoxyribose)
(a) Atomic structure
Figure 3.24
Adenine (A) Guanine (G)
Thymine (T) Cytosine (C)
Adenine (A) Guanine (G) Thymine (T) Cytosine (C)
Space-filling model of DNA
Nucleic Acids
Monomers of nucleotides
joined together to form nucleic
acid.
• Covalent bonds between the sugar of one nucleotide and the phosphate of the nextform a sugar-phosphate backbone.
• Nitrogenous bases hang off the sugar-phosphate backbone.
RNA, ribonucleic acid, is different from DNA.
• RNA uses the sugar ribose instead of deoxyribose
• RNA uses the base uracil (U) instead of thymine (T).
• RNA is usually single-stranded, but DNA usually exists as a double helix.
RNA
Proteins
Proteins are macromolecules • composed of C, H, N, O and S.
• Built in your body from the instructions in DNA
• are polymers constructed from amino acid monomers
• account for more than 50% of the dry weight of most cells
• perform most of the tasks required for life
• form enzymes, chemicals that change the rate of a chemical reaction without being changed in the process.
Structural Proteins(provide support)
Keratin
Storage Proteins(provide amino
acids for growth)
ContractileProteins
(help movement)
Transport Proteins(help transport
substances)
Figure 3.15e
Enzymes(help chemical
reactions)
Proteins are made of amino acid monomers
Aminogroup
Carboxylgroup
Sidegroup
The general structure of an amino acid
Figure 3.16b
Hydrophobicside group
Hydrophilicside group
Leucine Serine
Proteins
• Cells link amino acids together forming peptide bonds creating long chains of amino acids called polypeptides.
Figure 3.17-1Carboxyl Amino
OH H
Figure 3.17-2
Dehydration reaction
Carboxyl Amino
Peptide bond
H2O
OH H
• Your body has tens of thousands of different kinds of proteins each with a different function/JOB!!!!
• Proteins differ in their arrangement of amino acids.
• The specific sequence of amino acids in a protein is its primary structure.
Proteins
• A slight change in the primary structure of a protein affects its ability to function.
• The substitution of one amino acid for another in the protein hemoglobin causes sickle-cell disease, an inherited blood disorder.
Proteins
Protein ShapeUp to 4 Levels of Organization
1. Sequence = primary structure2. Amino acids in the chain are
twisted or folded3. Chain is twisted or folded4. Complex proteins with multiple
polypeptide chains – each chain has a specific arrangement.
Protein shape is very important!!!!
ENZYMES are PROTEINS!!
• Metabolism is the total of all chemical reactions in an organism.
• Most metabolic reactions require the assistance of enzymes which are proteins that speed up chemical reactions.
• All living cells contain thousands of different enzymes, each promoting a different chemical reaction.
Chemical Reactions
Matter and Energy cannot be created or destroyed…..they can only be transformed
or transferred!!
Energy is either released or absorbed when chemical bonds form or are broken.
Chemical Reactions
Reactants ProductsWhat you start with What you end up with
Activation Energy
Not all reactions that release energy occur
spontaneously, they need a push!!
Activation Energyis the energy that is needed to start
a reaction.
Catalysts• A catalyst is a substance that speeds up
the rate of a chemical reaction, it works by lowering the activation energy.
Enzymes
Enzymes are proteins that act as biological catalysts, they speed up chemical reactions that take place in cells.
Enzymes
Lactose intolerance!!
Enzymes
Figure 5.9-1
Active site
Enzyme
(sucrase)
Ready for
substrate
1
Figure 5.9-2
Active site
Enzyme
(sucrase)
Ready for
substrate
Substrate (sucrose)
Substrate
binding
1
2
Figure 5.9-3
Active site
Enzyme
(sucrase)
Ready for
substrate
Substrate (sucrose)
Substrate
binding
Catalysis
H2O
1
2
3
Figure 5.9-4
Active site
Enzyme
(sucrase)
Ready for
substrate
Substrate (sucrose)
Substrate
binding
Catalysis
H2O
Fructose
Glucose
Product
released
4
1
2
3
Enzymes – The process
• An enzyme is very selective in the reaction it catalyzes (a catalyst is a substance that speeds up the rate of reaction)
• Each enzyme recognizes a substrate, which is a specific reactant molecule.– The active site fits to the substrate, and
the enzyme changes shape slightly.– This interaction is called induced fit because
the entry of the substrate induces the enzyme to change shape slightly.
– The enzyme then turns the reactant into a product and releases the product.
– The enzyme is now free to catalyze another reaction.
Protein Shape
– A protein’s shape is sensitive to the surrounding environment.
– An unfavorable change in temperature and/or pH can cause denaturation of a protein, in which it unravels and loses its shape.
– High fevers (above 104F) in humans can cause some proteins to denature.
What Factors Effect Enzymes?
• pH• Temperature – most enzymes in the
human body function best at 37°C (average normal body temperature in humans)
Both these factors can change the shape of the enzyme, which changes its ability
to function properly.
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