Chapter 3Chapter 3

BiochemistryBiochemistry

WaterWater

• Water has 4 important properties.Water has 4 important properties.

• Water is polar.Water is polar.

• Water has hydrogen bonding.Water has hydrogen bonding.

• Water is cohesive.Water is cohesive.

• Water is adhesive.Water is adhesive.

PolarityPolarity

• Many of water’s biological functions stem from Many of water’s biological functions stem from its chemical structure.its chemical structure.

• The hydrogen and oxygen in water share The hydrogen and oxygen in water share electrons with covalent bonds.electrons with covalent bonds.

• These atoms do not share the electrons These atoms do not share the electrons equally.equally.

• Since the oxygen atom is bigger than the Since the oxygen atom is bigger than the hydrogen atoms, the electrons tend to hang hydrogen atoms, the electrons tend to hang around the oxygen atom more often.around the oxygen atom more often.

• This gives oxygen a small negative charge and This gives oxygen a small negative charge and the hydrogen a small positive charge.the hydrogen a small positive charge.

• A polar molecule is when opposite ends A polar molecule is when opposite ends have opposite charges. Not charges like have opposite charges. Not charges like ionic bonds but smaller attractions that ionic bonds but smaller attractions that sometimes only water has.sometimes only water has.

Being polar leads to other Being polar leads to other things like………things like………

• Hydrogen bondsHydrogen bonds

• This occurs when the slightly positive This occurs when the slightly positive hydrogen atom is attracted to a slightly hydrogen atom is attracted to a slightly negative oxygen atom of another water negative oxygen atom of another water molecule, it is a very weak attraction.molecule, it is a very weak attraction.

hydrogen

oxygen

CohesionCohesion

• This occurs when molecules of the This occurs when molecules of the same kind stick to one anothersame kind stick to one another

Cohesion creates surface Cohesion creates surface tension.tension.

Water is very sticky!

AdhesionAdhesion

• This is when molecules that are not This is when molecules that are not alike are attracted, example, water to alike are attracted, example, water to walls of a test tube, or plant wallswalls of a test tube, or plant walls

• When you see adhesion, think When you see adhesion, think adhesive, sticky.adhesive, sticky.

CapillarityCapillarity

• This is when water This is when water goes up a small, goes up a small, narrow tube like a narrow tube like a plant stem or plant stem or paper towel.paper towel.

• Adhesion makes Adhesion makes this possible.this possible.

Water’s Unique PropertiesWater’s Unique Properties

• Water has 4 unique properties.Water has 4 unique properties.

1

Water is polar.

2

Water makes hydrogen bonds. 3

Water is cohesive.

4

Water is adhesive.

Density of Water is Special!Density of Water is Special!

• Water is one of the only substances on Earth in Water is one of the only substances on Earth in which the solid phase is less dense than the which the solid phase is less dense than the liquid phase!liquid phase!

• Because of this, life can exist in many places.Because of this, life can exist in many places.

When winter comes, the ice When winter comes, the ice floats and keeps fish safe.floats and keeps fish safe.

ICE

Ouch!

If ice was actually denser than If ice was actually denser than water…….water…….

I wish I could get to safer water

below!

Temperature ModerationTemperature Moderation• Water must gain or lose a relatively large Water must gain or lose a relatively large

amount of energy for its temperature to amount of energy for its temperature to change.change.

• When water is heated, most of the thermal When water is heated, most of the thermal energy that the water initially absorbs energy that the water initially absorbs breaks the hydrogen bonds between the breaks the hydrogen bonds between the molecules.molecules.

• When the bonds are broken, the thermal When the bonds are broken, the thermal energy is released and increases the energy is released and increases the motion of the molecules.motion of the molecules.

• Water’s ability to absorb large amounts of Water’s ability to absorb large amounts of energy helps keep cells at an even energy helps keep cells at an even temperature despite temperature changes temperature despite temperature changes in the environment.in the environment.

Carbon CompoundsCarbon Compounds

• A carbon atom has 4 electrons in its A carbon atom has 4 electrons in its outer level which means it can create outer level which means it can create 4 bonds with any other atoms 4 bonds with any other atoms including itself.including itself.

• This makes carbon an excellent This makes carbon an excellent backbone for many organic molecules.backbone for many organic molecules.

• Carbon can even form rings and Carbon can even form rings and double and triple bonds!double and triple bonds!

Functional GroupsFunctional Groups• A functional group is a group of atoms A functional group is a group of atoms

that influence the properties of the that influence the properties of the molecules they compose.molecules they compose.

• Alcohol is a functional group that has Alcohol is a functional group that has oxygen and hydrogen attached.oxygen and hydrogen attached.

• Alcohols can cause blindness or even Alcohols can cause blindness or even death when consumed.death when consumed.

• Some alcohols are important to Some alcohols are important to assemble certain molecules in the assemble certain molecules in the body.body.

Large Carbon MoleculesLarge Carbon Molecules

• In large carbon compounds, the In large carbon compounds, the molecules are built up from smaller, molecules are built up from smaller, simpler molecules called monomers.simpler molecules called monomers.

• Monomers can bind together to Monomers can bind together to create larger, more complex create larger, more complex molecules called polymers.molecules called polymers.

• Large polymers are called Large polymers are called macromolecules.macromolecules.

How are polymers made and How are polymers made and broken?broken?

• Monomers link together in a condensation Monomers link together in a condensation reaction.reaction.

• When two monomers combine, water is When two monomers combine, water is released.released.

• When polymers are broken, it is called a When polymers are broken, it is called a hydrolysis reaction.hydrolysis reaction.

• Water is broken into two parts and breaks Water is broken into two parts and breaks the bonds that holds the monomers the bonds that holds the monomers together.together.

Energy CurrencyEnergy Currency

• Life processes require energy.Life processes require energy.

• This energy is available to life in the This energy is available to life in the form of a compound called ATP.form of a compound called ATP.

• ATP has three phosphates on the ATP has three phosphates on the molecule and when one phosphate is molecule and when one phosphate is broken off, energy is released.broken off, energy is released.

CarbohydratesCarbohydrates• A monomer of a carbohydrate is A monomer of a carbohydrate is

called monosaccharide.called monosaccharide.

• A monosaccharide is a simple sugar.A monosaccharide is a simple sugar.

• Two monosaccharides form a Two monosaccharides form a disaccharide.disaccharide.

• A polysaccharide is a complex A polysaccharide is a complex molecule composed of three or more molecule composed of three or more monosaccharides.monosaccharides.

• What are some carbs?What are some carbs?

ProteinsProteins• Proteins are organic compounds made Proteins are organic compounds made

from monomers called amino acids.from monomers called amino acids.• There are 20 different amino acids.There are 20 different amino acids.• The differences between the amino acids The differences between the amino acids

are their R groups.are their R groups.• Two amino acids bond to form a dipeptide.Two amino acids bond to form a dipeptide.• In a condensation reaction, two amino In a condensation reaction, two amino

acids form a covalent bond called a acids form a covalent bond called a peptide bond.peptide bond.

• Long chains of amino acids are called Long chains of amino acids are called polypeptides.polypeptides.

• What are some proteins?What are some proteins?

Enzymes are a special kind of Enzymes are a special kind of protein.protein.

• Enzymes are proteins that are important Enzymes are proteins that are important catalysts for chemical reactions.catalysts for chemical reactions.

• Enzyme reactions depend on the physical Enzyme reactions depend on the physical fit between the enzyme and the substrate.fit between the enzyme and the substrate.

• The substrate is the reactant being The substrate is the reactant being catalyzed.catalyzed.

• Enzymes may fail to work when the Enzymes may fail to work when the temperature isn’t correct.temperature isn’t correct.

• Other chemicals and pH are also a factor.Other chemicals and pH are also a factor.

Affects on EnzymesAffects on Enzymes• Temperature-raising of lowering Temperature-raising of lowering

temperature can cause an enzyme to temperature can cause an enzyme to malfunctionmalfunction

• Denature-a protein unravels when it Denature-a protein unravels when it gets too hotgets too hot

• A change in pH can decrease the A change in pH can decrease the ability of an enzyme to function.ability of an enzyme to function.

• A foreign chemical or metal can A foreign chemical or metal can decrease the ability of an enzyme to decrease the ability of an enzyme to function.function.

LipidsLipids

• Lipids are large, non polar molecules Lipids are large, non polar molecules that do not dissolve in water.that do not dissolve in water.

• Fatty acids are unbranched carbon Fatty acids are unbranched carbon chains that make up most lipids.chains that make up most lipids.

• Hydrophilic-water-loving, molecules Hydrophilic-water-loving, molecules dissolve in waterdissolve in water

• Hydrophobic-water-fearing, Hydrophobic-water-fearing, molecules do not dissolve in watermolecules do not dissolve in water

Types of LipidsTypes of Lipids• A triglyceride is composed of three molecules A triglyceride is composed of three molecules

of fatty acids joined to an alcohol called of fatty acids joined to an alcohol called glycerol.glycerol.

• Phospholipids have two fatty acids joined with Phospholipids have two fatty acids joined with glycerol.glycerol.

• Phospholipids are contained in the cell Phospholipids are contained in the cell membrane and form a double layer to create a membrane and form a double layer to create a barrier between the inside and outside of cell.barrier between the inside and outside of cell.

• A wax is a type of structural lipid.A wax is a type of structural lipid.

• A steroid has 4 carbon rings. Cholesterol is an A steroid has 4 carbon rings. Cholesterol is an example. Steroids are also hormones and very example. Steroids are also hormones and very important for life.important for life.

Types of Fats(Lipids)Types of Fats(Lipids)

• A saturated fat has all available bonds A saturated fat has all available bonds used by hydrogen.used by hydrogen.

• Saturated fats are solid at room Saturated fats are solid at room temperature and are all single bonded, temperature and are all single bonded, straight chainsstraight chains

• Unsaturated fats have a double bond Unsaturated fats have a double bond which means not all available bonds are which means not all available bonds are taken by hydrogen.taken by hydrogen.

• Unsaturated fats are generally liquid at Unsaturated fats are generally liquid at room temperature and are healthier.room temperature and are healthier.

Nucleic AcidsNucleic Acids• Nucleic acids are large and complex organic Nucleic acids are large and complex organic

molecules that store important information molecules that store important information in the cell.in the cell.

• RNA stores and transfers information to RNA stores and transfers information to make proteins.make proteins.

• DNA contains information that is essential DNA contains information that is essential for cell activities.for cell activities.

• Both RNA and DNA are composed of Both RNA and DNA are composed of monomers called nucleotides.monomers called nucleotides.

• A nucleotide has 3 components: a A nucleotide has 3 components: a phosphate group, a sugar and a nitrogen phosphate group, a sugar and a nitrogen base.base.

Nucleotide

DNA

Essential QuestionsEssential Questions

• 1. Describe the structure of the water 1. Describe the structure of the water molecule.molecule.

• 2. What are two properties of water 2. What are two properties of water that are caused by hydrogen that are caused by hydrogen bonding?bonding?

• 3. What is an organic compound?3. What is an organic compound?

• 4. Define functional group and give 4. Define functional group and give an example.an example.

Essential QuestionsEssential Questions

• 5. How does a polymer form?5. How does a polymer form?• 6. How does a polymer break down?6. How does a polymer break down?• 7. What are the 4 classes of organic 7. What are the 4 classes of organic

compounds? Give an example of each.compounds? Give an example of each.• 8. Explain the relationship between 8. Explain the relationship between

enzyme and substrate.enzyme and substrate.• 9. What affects the ability of enzymes 9. What affects the ability of enzymes

to work?to work?