Unit 2The Chemistry of Life

Learning Targets Identify elements common to living things. Describe how ions work. Compare ionic and covalent bonds Recognize the importance of hydrogen bonding. Explain why many compounds dissolve in water. Compare acids and bases. Describe the bonding properties of carbon atoms Compare and understand the importance of the four

macromolecules: carbohydrates, lipids, proteins, and nucleic acids. Describe how bonds break and reform during chemical reactions Explain why and how chemical reactions release or absorb energy. Explain the effect of catalysts on activation energy. Describe and explain how enzymes regulate chemical reactions.

Unit Opener-How can this plant

digest a frog?

Like other carnivores, the Venus flytrap eats animals to get nutrients that it needs to make molecules such as proteins and nucleic acids. Other chemical compounds made by plant’s cells enable the Venus flytrap to digest the animals that it eats. These chemicals are similar to the chemicals that allow you to digest the food that you eat.

???????? If plants can make their

own food through photosynthesis, why would a plant species

evolve a mechanism to capture and eat animals?

The animal must be supplying nutrients that the plant cannot get from other sources.

Venus fly traps grow in swampy areas that have nitrogen poor soil. These plants get the nitrogen they need for survival by trapping and digesting animals.

Video

http://www.youtube.com/watch?v=O7eQKSf0LmY

What is everything made up of?

Atoms- the building block of matterMatter- anything that takes up

space

Atoms are made up of:Protons-> positively charged

particles and denseNeutrons-> neutral charge / no

chargeElectrons-> negatively charged

particles and smallProtons and neutrons live in

the nucleus (center of the cell)Electrons are in the outer

levels= electron cloud

Draw and label the atom

What do the numbers mean?

Atomic mass= sum of protons and neutrons in the nucleus

Atomic number = the amount of protons and electrons in a neutral atom

ElementA type of atom that cannot be

broken down into simpler substances.

Can also be a group of atoms of the same type.

Ex-> gases such as hydrogen and oxygen. Metals= aluminum and gold.

Atoms are made up of the same types of particles, so what

makes one element different from another?Different elements differ in the number of protons they have.

Atomic number= number of protons

Atomic Mass

How many protons does hydrogen have? Oxygen?

Hydrogen= 1Oxygen= 8

Energy levelsDifferent energy levels can

hold a different number of electrons.

1st energy level= hold 2 electrons

2nd level= hold 8 electronsStable atoms have a full

outermost energy level

91 elements that occur naturally

4 that make up 96 % of your body= carbon, oxygen, nitrogen, and hydrogen

The other 4% are called trace elements because they are found in little amounts but we need them to survive-> such as calcium, iron, potassium

Why does your blood need iron?

To transport oxygen in your blood

Why does your body need chromium?

Your cells need it to break down sugars for usable energy

CompoundsAtoms of elements found in organisms

are usually linked or bonded to other atoms= compound.

Common compounds= water (H2O), carbon dioxide (CO2)

Ions Atom that has gained or lost one or more

electrons. Forms because an atom is more stable

when its outermost energy level is full. The gain or lose results in a full outer level.

Either positive or negative Atoms with few electrons= lose electrons

and becomes more positive Gains electrons= more negative.

NaCl Transfers electron from

sodium atom to chlorine atom

When sodium loses electron it becomes positive-> full charged because it has a filled outermost energy level.

The electron lost goes to the chlorine ion, causing the chlorine to become more negative and have a full energy level.

End product is an ionic bond-> bond that forms when two oppositely charged particles exchange electrical forces.

Opposites attract (+ / -)

What determines whether an atom

becomes a positive ion or a negative ion?

Atoms with few outer electrons tend to lose electrons and form positive ions; atoms with almost full outer energy levels tend to gain electrons and form negative ions.

Molecule

Two or more atoms held together by covalent bonds.

Covalent Bonds

The strongest of bondsForm when atoms share a pair of

electrons.Need 4 electrons to fill its

outermost energy level

CO2= Carbon Dioxide

An oxygen atom needs 2 electrons to fill its outer energy level. In Carbon dioxide, carbon makes a double bond, or shares two pairs of electrons with each oxygen atom.

C OO

Properties of Water!!!!!

Waters unique properties allow life to exist on

Earth.

Polar vs. NonpolarPolar: Water and some gasesUneven distribution of electrons

Nonpolar= liquids, CO2, Oxygen, oils, fats

electrons are distributed more evenly around the outer shell and cancel each other out

They both tend to remain separate that is why they say “oil and water don’t mix.”

Life depends on hydrogen bonds

Water is polar-> Have regions with a slight positive and slight negative charge.

Waters oxygen atoms are slightly negative and hydrogen is slightly positive= HYDROGEN BOND

The weakest of bonds

Important structures in DNA and proteins.

Properties of Hydrogen Bonds

Weakest of the bondsHigh specific heat= water resists

changes in temperature, therefore water must absorb more heat energy to increase temperature. Very important with cells because our

cells release a lot of heat and water absorbs that heat which allows us to regulate cell temperatures.

Properties ContinueCohesion->

attraction among molecules of a substance.

Makes water molecules stick together.

Ex- beads on a car when it is washed

Spider walking on top of the water (surface tension).

http://www.youtube.com/watch?v=8O8PuMkiimg

Properties Cont. Adhesion-> attraction

among molecules of different substances.

Water molecules stick to other things.

Ex- upward curve of the surface of the water-> graduated cylinder

Ex- plants transport water up their roots to their leaves.

http://www.youtube.com/watch?v=45yabrnryXk

http://www.youtube.com/watch?v=WpXHpXKZtws

Many compounds dissolve in water- Universal Solvent

Molecules and ions can’t take part in chemical processes inside cells unless they dissolve in water.

Materials such as sugar and oxygen cannot be transported from one part of an organism to another unless they are dissolved in blood, plant sap, or water based fluids.

Solution= mixture of substances that is the same throughout=

homogeneous mixtureSolvent-> substance that is

present in the greatest amount, and is the substance that dissolves solutes.

Example= Water

Solute-> substance that dissolves. Example= kool aid powder

SolubilityThe ability of the solute to dissolve

into the solvent.Typically measured by how fast or

the rate. Temperature increases the rate at

which the solute dissolves.Pressure increases the rateThe nature of the solute and

solvent (what its made up of).

Your plasma (liquid part of your blood) is 95% water. Which is the solvent and

solute?Solvent= water; Solute is the other

5% which is made up of proteins, sugars, minerals, platelets, etc

Why do the solutes such as proteins and sugars dissolve in the water of

blood plasma?Answer-> polar= because the

attraction between the water molecules and the solute molecules is greater than the attraction among the molecules of the solutes.

Sum it up! Properties of Water: Hydrogen Bonding- strong cohesion

(insects walking on water) Capillary Action- water moves upward

(Roots to leaves) Strong Adhesion- attraction between two

unlike substances Universal Solvent- dissolves everything High Specific Heat- cools / heats up

slowly to allow temperatures in organisms to maintain homeostasis

Expands when freezes making it less dense

1. What is the most comment solvent in everyday life?

1. A. carbon containing chemicals

2. B. ethanol3. C. water4. D. All of the above

2. In a solution (which is a mixture of a solute and a solvent) which do you typically have more of?

a. Soluteb. Solventc. Same amount of both

3. What is solubility?a. The ability of a given

substance(solute) to dissolve into a solvent.

b. The ability of a given substance(solvent) to dissolve into a solute.

4. How does temperature affect solubility?

a. Solubility is not affected by temperature.

b. Solubility decreases with an increase in temperature.

c. Solubility increases with an increase in temperature.

5. How does a solute dissolve into a solvent?a. Polar solvent molecules separate the

molecules of other polar substances.b. Polar solvent molecules separate the

molecules of other non-polar substances.c. Non-polar solvent molecules separate the

molecules of other non-polar substances.

6. What are the main factors that affect solubility?a. Temperatureb. Pressurec. Nature of solute and solventd. All of the above

Answers1. C- Water2. B3. A4. C5. A6. D

Acids and BasesAcids

Releases a hydrogen ion (H+) when it dissolves in water.

0 to 7= acids

BasesRemoves H+ ions from a solution7-14= basic

pH of 7=Neutral-> neither acidic or basic

Strong Acid

Weak Acid

Weak base Strong

Base

pH Scale (Potential Hydrogen)

How is Ph regulated in our bodies?

Through buffers-> compounds that can bind to H+ ion when the H+ concentration increases and can release an H+ ion when the H+ ion decreases.

Buffer “locks up or stops” the H+ ions in order for our bodies to maintain homeostasis.

Example-> normal Ph of blood is 7.35-7.45 (slightly basic), therefore a small change in this could really disrupt your cells and can be fatal.

Carbon Based

Molecules

Carbons unique bonding properties

Building blocks of life because they are the basis of most molecules that make up living things.

Organisms obtain energy (food) and turn it into ATP (cells power source for all life processes).

Unique atomic structure because it has four unpaired electrons on the outer energy level and can form covalent bonds with up to four other atoms!!!!!!

Three types of molecular structures

Straight ChainBranched

ChainRing

Monomer / Polymer

Monomer= small molecular subunit

Polymer= molecule that contains manyMonomers bonded together.

How many monomers are above?

Four Carbon Based Molecules in Living

Things / Macromolecules1. Carbohydrates

2. Lipids3. Proteins4. Nucleic Acids

CarbohydratesFruits, grains, sugars, starchesMonosaccharides, Disaccharides,

PolysaccharidesMade up of carbon, oxygen, and

hydrogen in a 1:2:1 ratioWhen broken down they provide a

source of usable chemical energy for cells

Major part of plant cell structure too!!!

MonosaccharidesMonomersSimple sugars -> glucose=

C6H12O6

DisaccharidesTwo monosaccharides linked togetherTransport forms= organisms use it to

move glucose from place to placeEx- Sucrose= common table sugar

(made from glucose and fructose)Ex- Lactose= milk sugar (made from

glucose and galactose)

PolysaccharidesMany monosaccharides linked

together to form long branches or chains.

PolymersEx- starch and glycogen -> energy

storage in plants and animalsEx- Cellulose- cell walls in plants

Lipids Nonpolar molecules that are insoluble in

water (they don’t dissolve) Examples such as fats, oils (coconut, olive,

corn), waxes, cholesterol, steroids, fatty acids, glycerol,

Function- Some are broken down for cell use, some are stored for later energy use, and others are parts of cell structures.

Monomer- glycerol Polymer- fatty acids

3 Main Lipids1. Fats or Triglycerides= energy

storage moleculesThree fatty acids bonded to glycerol

2a. Saturated fatty acids= held together by a single covalent bond and is solid at room temperature.

Has the maximum number of hydrogen atoms possible

2b. Unsaturated fatty acids= one or more double bonds between the carbon atoms.

Not saturated with hydrogen atoms

2c. Polyunsaturated- two or more double covalent bonds

Good fatty acids

3. PhospholipidsForm the bilayer of the cell

membraneOne glycerol, two fatty acids, and a

phosphateHydrophobic tails- afraid of water

(non-polar)Hydrophilic heads- love water

(polar)

Proteins Most varied- a part of everything from

moving your leg to digesting your pizza. Protein is the polymer made up of monomers

called amino acids. Amino acids are referred to as the “building

blocks” of proteins and are thought to be the first molecules on Earth. We use 20 different amino acids to build proteins

in our bodies. Your body makes 12 and the others need to be

ingested through meat, beans, and nuts.

Amino Acids All have similar structures:

hydrogen atom, an amino group (NH2), and a carboxyl group (COOH).

NH2 and COOH are always present.

The R group (side group) is different for each group

Central carbon is covalently bonded to four atoms (functional group) with one always being a hydrogen.

Proteins Cont. Held together by covalent bonds called peptide

bonds. The bonds form between the amino group of one amino acid and the carboxyl group of another amino acid.

• Polypeptide forms between two amino acids• They are a single chain of three or more amino acids linked

together by peptide bonds.

Peptide bond

Functions of Proteins1. Catalyzing enzymes- speed

up the rates of reactionsActivate metabolic reactionsLowers activation energy-> the

amount of energy to get a reaction started

On-goingNeeds certain factors-> pH,

temperature, and concentrationEx- Human enzymes work best at

98.6, above 104 they fall apart.

2. Defensive proteins- basis of the bodies endocrine and immune systems. They attack invading microbes and cancer cells. Ex- antibodies attack viruses and bacteriaEx- fibrinogen = protein that causes your

blood to clot3. Storage proteins / Nutrient - bind

with iron and calcium to provide nourishment for an organism.

4. Transport proteins- allows larger molecules to move in and out of cells.Ex- Hemoglobin= carries oxygenEx- Myoglobin= carries oxygen to muscles

5. Support Proteins- provide structural support and protection.Ex- Keratin in your hair, skin, and nailsEx- Fibrin- allows your blood to clotEx- Collagen and elastin- major components

of connective tissue6. Motion Proteins such as myosin and

actin cause muscles to contract or change shape.

7. Messenger proteins- allow different cells to communicate.

Ex- Hormones- regulate body functionsEx- Insulin- regulates glucose levelsEx- Vasopressin- tells your kidneys to

reabsorb water

Nucleic Acids Detailed instructions that build proteins and

are stored in extremely long carbon based molecules.

Nucleic acid = polymer Nucleotides = monomer Nucleotides are made up of: sugar,

phosphate group, and a nitrogen base (Adenine, thymine, guanine, and cytosine.

Two types= DNA and RNA ONE FUNCTION!!!!!-> DNA and RNA work

together to make proteins. DNA passes on genetic instructions to RNA. RNA decodes and turns the genetic information into a protein.

DNA is the basis of genes and heredity.

Chemical ReactionsWhen substances are changed into

different substances by breaking and forming chemical bonds.

Reactants vs. Products

Reactants ProductsLabel Them!!!!

What causes bonds in oxygen and glucose molecules to break?

Energy is added that causes the bonds to break into oxygen and glucose.

Each bond requires a different amount of energy= Bond Energy

What happens when new bonds form in carbon dioxide and water?

When new bonds form, energy is released and this energy that is released is equal to the amount of energy that breaks the same bond.

Sometimes bonds can form a chemical equilibrium, meaning they are reversible and the same on both sides of the equation.

Example of EquilibriumBlood cells and

plasma transport materials throughout the body. Carbonic acid dissolves in the blood so that carbon dioxide can be transported to the lungs.

Chemical reactions release or absorb energy

Energy added = breaks chemical bonds

Energy released= new bonds formEnergy is released or absorbed and

in different amounts.

Activation energyAmount of energy that needs

to be absorbed for a chemical reaction to start.

Ex.- the energy you would need to push a rock up a hill.

ExothermicReleases more energy than it

absorbsExcess energy is typically given off

in heat or lightReactants have more energy than

productsEx- firefly squid, fireflies, cellular

respiration (releases usable energy as well as keep your body warm).

EndothermicAbsorbs more energy than it

releasesProducts have more energy

than reactantsExample- photosynthesis->

plants absorb energy from the sun and use that energy to make simple and complex carbs.

Enzymes

How did the Venus Flytrap digest the frog?

Enzymes-> type of protein that helps start and run chemical reactions in living things.

Break down food into smaller molecules that the body can use.

What is activation energy?The energy needed to get things started

Most of the time the activation energy for a chemical reaction comes from an increase in temperature-> sometimes the process is very slow.

In order to speed the process up substances called catalysts decrease the activation energy needed to start the chemical reaction -> in the end it increases the chemical reaction.

When a catalyst (ex- enzymes) is present less energy is needed and products form a lot faster.

What are two functions of catalysts in chemical

reactions?1. Decrease activation energy

2. Increase reaction time.

Enzymes Definition= catalysts for chemical reactions in

living things (made by proteins) Reactants are usually found at very low

concentrations in the body, but really need to occur quickly.

Almost all are proteins= long chains of amino acids

Each one depends on its structure to function Temperature, concentration, and pH can affect

the shape, function, rate, and activity of the enzyme.

Work best at normal body temperature

If temperature is a little elevated then the hydrogen bonds will fall apart, the enzymes structure will change, and its ability to function will be lost.

This is the reason why a high temperature / fever is very dangerous to a person.

Examples of enzymes in action

Amylase is an enzyme in saliva that breaks down starches into simpler sugars. Without amylase it would take a million times slower for you to chew, swallow, and digest your food.

Blood cell engulfing a pathogen

ENZYME CHEMICAL ACTED UPON PRODUCTS

Lipase Fats & oils Glycerol & fatty acids

Amylase Starch Maltose Maltase Maltose Glucose Pepsin Protein Polypeptides

Protease Polypeptides Amino acids

Catalase Hydrogen peroxide

Water and oxygen

The structure is so important because each enzyme’s shape is specific to a certain reactant= allows them to fit perfectly together just like a key fits into a lock

Specific reactant an enzyme acts on are called substrates

The sites where substrates bind to enzymes are called active sites.

Enzymes bring substrate molecules close together, then they decrease activation energy, substrates attach together and their bonds are weakened, and then the catalyzed reaction forms a product that is released from the enzyme.

Videoshttp://highered.mcgraw-hill.com/sit

es/0072495855/student_view0/chapter2/animation__how_enzymes_work.html

http://www.youtube.com/watch?v=NdMVRL4oaUo

ReflectionOn a sheet of paper, review the three

parts of the lock and key model and write a paragraph (3-5 sentences) describing the analogy. Consider why the model is described as a lock and key. Also identify the different parts and what happens to each part after the reaction is complete. You may use your notes