Chemistry of Life

MCAS Review

Inorganic Chemistry

Types of Bonds

Type Formed When… Characteristics

Ionic Electron is Transferred

Between atoms with different electronegativity

Covalent Electron is Shared Very strong bond

Van der Waals Forces or Hydrogen Bonds

Attraction between oppositely charged regions of molecules

Hydrogen bonds individual = weak

many = strong

Ionic – Electron Transferred

Covalent – Electron Shared

Van der Waals Forces (oppositely charged regions )

Properties of Water

#1Polarity• Water molecules

have a slightly negative charge near the oxygen atom and a slightly positive charge around the hydrogen atom.

Properties of Water

#2 Universal Solvent• Water dissolves more

substances than sulfuric acid because of its polar characteristic. It can surround molecules of a substance and pull it apart.

Properties of Water

#3 Cohesion • Water is attracted to

other water. This is called cohesion.

Properties of Water

#4 Adhesion• Water can also be

attracted to other materials. This is called adhesion.

Properties of Water

#5 Density• Ice is less dense

than water which is

why it floats.

It expands as it freezes

Fish can live in water during winter

Properties of Water

• Surface Tension• Cohesion of water

molecules at the surface of a body of water causes the water to pull itself into a shape with the smallest amount of surface area (sphere).

• Surface tension allows water striders to 'skate' across the top of a pond. (Cohesion)

Properties of Water• Capillary Action• Adhesive properties of

water. Placing a straw into a glass of water, it 'climbs' up the straw. Molecules are attracted to the straw molecules (adhesion). When one water molecule moves, the other water molecules follow (cohesion)

• Capillary action is limited by gravity and the size of the straw. Plants take advantage of capillary action to pull water into the roots.

Cohesion or Adhesion?

Define Organic!

• Compounds that contain carbon atoms that are covalently bonded to other elements; typically: hydrogen, oxygen, and other carbon atoms.

Importance of Carbon (C)# C is in all living Things# C is necessary for ALL life# C can bond with other C; giving it the ability to form long chains or ringsMacromoleculesAKA= “Giant Molecules”# Made from 100’s to 1000’s of smaller molecules# Smaller molecules are called “monomers”# Monomer + Monomer = Polymer# Polymers are formed by a process called polymerization

Carbon

CHNOPS

• The six most common elements that make up biological organisms are:Carbon Hydrogen NitrogenOxygen Phosphorus Sulfur

Categories of Organic Molecles

Molecule Building Blocks Examples Uses

Carbohydrates

C H O

Monosaccharides Sugars andStarches

Quick Energy

LipidsC H O

Glycerol and Fatty Acids

Fats, Oils, Waxes and Steroids

Stored EnergyCell Membranes

ProteinsC H N O

Amino Acids MuscleEnzymesCollagenAntibodies

Help Carry Out Cellular Activities

Nucleic AcidsC H N O P

Nucleotides DNA, RNA Instructions for all cell activities

Help make proteins

Carbohydrate (Hydrated Carbon)

Lipids (Glycerol and 3 Fatty Acids)Saturated / Unsaturated

Protein (Polymers of Amino Acids)

Nucleic Acid (Phosphate, Sugar, Base aka Pool, House and Barn)

4 Groups of Organic Compounds

Where do we get these molecules?

• From our Food!!!

Enzymes

Enzymes

• Enzymes = Catalysts that speed up reactions in our body

• Enzymes have a specific job – each fits like a lock and key with its specific substrate

How Enzymes Work

Four steps in the process of an enzyme working. 1. An enzyme and a substrate (the biological molecule that the enzyme will attack) are in the same area. 2. The enzyme grabs onto the substrate with a special area called the active site which is a specially shaped area of the enzyme that fits around the substrate. The active site is the keyhole of the lock. 3. A process called catalysis happens which is when the substrate is changed ( broken down or combined to make something new)4. When the enzyme lets go, it returns to normal, ready to do another reaction. The substrate is no longer the same and is now called the product.

Can you stop them????

• Good question!

• There are many factors that can regulate enzyme activity, including temperature, activators, pH levels, and inhibitors.

pH Scale

MCAS Review Questions

1. Which of the following best explains why enzymes are

necessary for many cellular reactions?

A. Enzymes supply the oxygen necessary for the reactions.

B.Enzymes change reactants from solid to liquid during the

reactions.

C.The reactions take up too much space in the cell if

enzymes are missing.

D.The reactions are too slow to meet the needs of the cell if

enzymes are missing.

1. Which of the following best explains why enzymes are necessary for many cellular

reactions?

D. The reactions are too slow to meet the needs of the cell if enzymes are missing.

2. Lemurs’ bodies are adapted to efficiently store energy for times when food is scarce. This adaptation may help to explain how lemur

ancestors survived the trip across the Mozambique Channel from mainland Africa to

Madagascar.Which of the following types of molecules are primarily used for long-term energy storage in

the lemur?

• A.lipids• B.monosaccharides• C.nucleic acids• D.proteins

2. Lemurs’ bodies are adapted to efficiently store energy for times when food is scarce. This adaptation may help to explain how lemur

ancestors survived the trip across the Mozambique Channel from mainland Africa to

Madagascar.Which of the following types of molecules are primarily used for long-term energy storage in

the lemur?

• A.lipids

3. In the human body, fibrinogen is necessary for sealing cuts and stopping the loss of blood. Since fibrinogen is made of chains of amino acids, it is

an example of which type • A.carbohydrate

• B.protein

• C.fatty acid

• D.nucleic acid

3. In the human body, fibrinogen is necessary for sealing cuts and stopping the loss of blood. Since fibrinogen is

made of chains of amino acids, it is an example of which

type

• B.protein

4. A scientist is analyzing a sample of tissue from a plant. Which of the following

elements will be most abundant in the

sample?

• A.zinc and copper

• B.sodium and chlorine

• C.carbon and hydrogen

• D.magnesium and calcium

4. A scientist is analyzing a sample of tissue from a plant. Which of the following

elements will be most abundant in the

sample?

• C.carbon and hydrogen

5. Baby food manufacturers sometimes use proteases in their products. Proteases catalyze the breakdown of the proteins in these foods, making digestion easier

for infants. Proteases are which of the following types of

molecules? • A.enzymes 

• B.fatty acids

• C.hormones 

• D.monosaccharides

5. Baby food manufacturers sometimes use proteases in their products. Proteases catalyze the breakdown of the proteins in these foods, making digestion easier

for infants. Proteases are which of the following types of

molecules? • A.enzymes 

6. Ovalbumin is a protein found in eggs. Which of the following best describes

the molecular structure of ovalbumin?

• A.a group of six carbon atoms joined in a ring• B.a chain of amino acids folded and twisted into

a molecule• C.a set of three fatty acids attached to a

molecule of glycerol• D.a sequence of nitrogenous bases attached to

a sugar-phosphate backbone

6. Ovalbumin is a protein found in eggs. Which of the following best describes

the molecular structure of ovalbumin?

• B.a chain of amino acids folded and twisted into a molecule

7. When lactose is digested by the human body, each lactose molecule is broken

down into smaller molecules. To which of the following categories of molecules

do these smaller molecules belong?

• A.amino acids

• B.monosaccharides

• C.nucleic acids

• D.polypeptides

7. When lactose is digested by the human body, each lactose molecule is broken

down into smaller molecules. To which of the following categories of molecules

do these smaller molecules belong?

• B.monosaccharides

8. A diagram of an organic molecule is belowWhich element is found at the positions marked by the

dots (•) in the molecule?

• A.carbon• B.nitrogen• C.phosphorus• D.sulfur

8. A diagram of an organic molecule is belowWhich element is found at the positions marked by the

dots (•) in the molecule?

• A.carbon

9. Students in a biology laboratory are monitoring the rate at which hydrogen peroxide breaks down to produce water and oxygen gas. They begin monitoring a sample of hydrogen peroxide and then add catalase, an enzyme that speeds up its

breakdown. Their data are shown in the table below.

• Time Rate of Hydrogen Peroxide Breakdown(molecules per min)0.00.000        0.50.030        1.00.032        1.54,970,000.000        2.05,001,000.000        2.54,985,300.000        3.05,021,700.000        

9. Students in a biology laboratory are monitoring the rate at which hydrogen peroxide breaks down to produce water and oxygen gas. They begin monitoring a sample of hydrogen peroxide and then add catalase, an enzyme that speeds up its breakdown. Their data are shown in the table below.Based on the data in this table, during which of the following time periods did the students add the catalase to the hydrogen peroxide?A.between 0.0 and 0.5 minB.between 1.0 and 1.5 minC.between 2.0 and 2.5 minD.between 2.5 and 3.0 min

• Time (min) Rate of Hydrogen Peroxide Breakdown(mol/min)

• 0.0 0.000        • 0.5 0.030• 1.0 0.032 • 1.5 4,970,000.000 • 2.0 5,001,000.000• 2.5 4,985,300.000

• 3.0 5,021,700.000        

9. Students in a biology laboratory are monitoring the rate at which hydrogen peroxide breaks down to produce water and oxygen gas. They begin monitoring a sample of hydrogen peroxide and then add catalase, an enzyme that speeds up its breakdown. Their data are shown in the table below.Based on the data in this table, during which of the following time periods did the students add the catalase to the hydrogen peroxide?

B.between 1.0 and 1.5 min

• Time (min) Rate of Hydrogen Peroxide Breakdown(mol/min)

• 0.0 0.000        • 0.5 0.030• 1.0 0.032 • 1.5 4,970,000.000 • 2.0 5,001,000.000• 2.5 4,985,300.000

• 3.0 5,021,700.000        

10. Some bacteria live in hot springs. Their cells contain enzymes that function best at temperatures of 70°C or

higher. At a temperature of 50°C, how will the enzymes in these bacterial cells most likely be affected?

• A.The enzymes will be destroyedby lysosomes.

• B.The enzymes will lose theirbond structure and fall apart.

• C.The enzymes will requireless energy to function thanat 70°C.

• D.The enzymes will not increase therate of reactions as much as theywould at 70°C.

10. Some bacteria live in hot springs. Their cells contain enzymes that function best at temperatures of 70°C or

higher. At a temperature of 50°C, how will the enzymes in these bacterial cells most likely be affected?

• D.The enzymes will not increase therate of reactions as much as theywould at 70°C.

Define chemical reaction.

• The process during which chemical bonds between atoms are broken and new ones are formed, producing one or more different substances.

Write an example of a chemical reaction and label the reactants and products.

• Na → Na+ + Cl-

• Reactants Products

Define activation energy.

• The energy needed to start a chemical reaction

Define enzyme.

• Proteins that increase the speed of a chemical reaction

How does an enzyme affect the activation energy for a chemical reaction?

• Enzymes are catalysts;

they reduce the activation energy needed for a chemical reaction to take place

Any factors that affect the shape of an enzyme affect the enzyme’s activity. What effect

does pH and temperature have on an enzymes ability to catalyze (speed up) a reaction?

• Enzymes work well within very specific ranges of pH and temperature. If the pH or temperature changes to outside of the range, the enzyme shape changes and thus no longer works to speed up the reaction.