biological molecules

CC: Why is carbon especially important to biological molecules?

Carbon can form 4 covalent bonds, allowing it to form chains, branches, and rings and therefore very complex biological molecules.

What is an organic compound?

A carbon-based compound; in biology, carbon is commonly bonded to other carbon atoms and/or hydrogen.

What is a hydrocarbon?

A molecule containing only carbon and hydrogen.

What is an example of a hydrocarbon discussed in lecture?

Methane, CH₄.

What properties do hydrocarbons have?

They are nonpolar, uncharged, and hydrophobic.

CC: Why are hydrocarbons hydrophobic?

They contain only C and H and are nonpolar, so they do not interact well with water.

What happens when hydrogen atoms in a hydrocarbon are replaced by functional groups?

The molecule's shape, properties, behavior, and ultimately function can change.

CC: Why are functional groups important?

They dramatically change the properties and function of carbon-based molecules.

CC: What is a functional group?

A group of atoms attached to a carbon skeleton that changes the molecule's properties and behavior.

CC: What should you know about each of the six functional groups?

Their name, formula, structure recognition, polarity/water behavior, acidic or basic properties, and biological examples.

Do you need to draw the six functional-group structures?

No. You need to recognize the structures.

CC: How many of the six functional groups are hydrophilic?

Five.

CC: Which of the six functional groups is the ONLY hydrophobic one?

Methyl.

CC: Which functional groups are acidic?

Carboxyl and phosphate.

CC: Which functional group is basic?

Amino.

CC: What is the hydroxyl functional group?

–OH; it is polar and hydrophilic and is common in alcohols.

What is the formula for hydroxyl?

–OH.

If you see –OH attached to a carbon skeleton, what functional group is it?

Hydroxyl.

What property does the O–H bond give the hydroxyl group?

Polarity.

CC: What is the carbonyl functional group?

C=O; it is polar and hydrophilic and is important in sugars.

What is the formula for carbonyl?

C=O.

If you see a carbon double-bonded to oxygen, what functional group is it?

Carbonyl.

Do you need to memorize the ketone versus aldehyde distinction for this lecture?

No, unless the professor later emphasizes it.

CC: What is the carboxyl functional group?

–COOH / –COO⁻; it is polar, hydrophilic, and acidic.

What is the formula for carboxyl?

–COOH / –COO⁻.

Why is the carboxyl group acidic?

It can release H⁺.

What happens to a carboxyl group when it loses H⁺?

It becomes the negatively charged carboxylate form, –COO⁻.

Where are carboxyl groups important?

In amino acids and fatty acids.

If you see –COOH, what functional group is it?

Carboxyl.

If a functional group can donate H⁺, is it acidic or basic?

Acidic.

CC: What is the amino functional group?

–NH₂ / –NH₃⁺; it is polar, hydrophilic, and basic.

What is the formula for amino?

–NH₂ / –NH₃⁺.

Why is the amino group basic?

It can accept H⁺.

Where is the amino group found?

In amino acids.

If you see –NH₂, what functional group is it?

Amino.

If a functional group can accept H⁺, is it acidic or basic?

Basic.

CC: What is the phosphate functional group?

–PO₄H₂ in the professor's representation; it is hydrophilic and acidic.

What element is central to the phosphate group?

Phosphorus.

What can a phosphate group do with H⁺?

It can release one or both H⁺ ions.

What charge does phosphate commonly have under biological conditions?

It is commonly ionized and negatively charged.

Where are phosphate groups important?

Phospholipids, nucleic acids, and ATP.

If you see a phosphorus-containing group bonded to oxygen, what functional group is it likely to be?

Phosphate.

CC: What is the methyl functional group?

–CH₃; it is nonpolar and hydrophobic.

What is the formula for methyl?

–CH₃.

Which functional group is the only hydrophobic member of the six discussed?

Methyl.

What is methyl associated with in DNA?

DNA methylation/epigenetic regulation.

If you see –CH₃, what functional group is it?

Methyl.

CC: Which functional group is polar and hydrophilic but neither acidic nor basic?

Hydroxyl.

CC: Which functional group is polar, hydrophilic, and found in sugars?

Carbonyl.

CC: Which functional group is acidic and can donate H⁺?

Carboxyl.

CC: Which functional group is basic and can accept H⁺?

Amino.

CC: Which functional group is acidic and commonly ionized/negatively charged?

Phosphate.

CC: Which functional group is nonpolar and hydrophobic?

Methyl.

What are Van der Waals interactions?

Relatively weak, short-lived interactions related to electron position and motion.

How can Van der Waals interactions become significant?

Many weak interactions can occur together and produce a strong overall effect.

What example did the professor use for many weak interactions adding up to strong adhesion?

Gecko feet.

What are hydrogen bonds?

Attractions involving partial charges, especially when H is covalently bonded to a highly electronegative atom such as O or N.

CC: Why do hydrogen bonds form?

O and N pull electron density more strongly than H, producing partial charges that can attract.

Are hydrogen bonds intermolecular or intramolecular?

Intermolecular.

Are covalent bonds intermolecular or intramolecular?

Intramolecular.

CC: What is the professor's relative strength order for these interactions?

Covalent > ionic > hydrogen bond.

What should you focus on more than London dispersion forces for this course?

Hydrogen bonds.

CC: Why is water polar?

Water's O–H bonds are polar covalent, creating partial negative and partial positive regions.

CC: What is the relationship between polarity and hydrogen bonding in water?

O–H polar covalent bonds create partial charges, making water polar and allowing hydrogen bonds to form.

What happens to hydrogen bonds in liquid water?

They constantly form, break, and reform.

CC: What is cohesion?

Attraction between water molecules.

CC: What is adhesion?

Attraction between water molecules and another substance.

How can you remember cohesion versus adhesion?

Cohesion = water + water; adhesion = water + something else.

What causes cohesion in water?

Hydrogen bonding between water molecules.

What causes adhesion?

Attraction between water molecules and another substance.

CC: What is high specific heat?

Water can absorb substantial heat before its temperature rises significantly.

CC: Why does water's high specific heat matter biologically?

It buffers temperature changes and helps organisms and ecosystems maintain more stable temperatures.

How does sweating cool the body?

Evaporation removes heat from the body.

What property of water is involved in evaporative cooling?

Water's ability to absorb and remove heat during evaporation.

CC: Why does water expand when it freezes?

Freezing produces a crystal arrangement in which water molecules are farther apart than in liquid water.

CC: Why is ice less dense than liquid water?

The molecules in ice are arranged farther apart.

CC: Why does ice float?

Ice is less dense than liquid water.

CC: Why is floating ice biologically important?

It can form an insulating layer that protects aquatic life below.

SEQ: What is the chain explaining why ice floats?

Hydrogen bonding → crystal arrangement → greater distance between molecules → ice floats.

CC: Why is water called a universal solvent?

Because water dissolves many polar, ionic, and charged substances.

What does hydrophilic mean?

Interacts well with water; in this guide, polar substances that dissolve in water.

What does hydrophobic mean?

Does not mix well with water; in this guide, nonpolar substances.

If a molecule is polar, is it more likely hydrophilic or hydrophobic?

Hydrophilic.

If a molecule is nonpolar, is it more likely hydrophilic or hydrophobic?

Hydrophobic.

CC: What are biological macromolecules?

Very large biological molecules that can contain hundreds, thousands, or even tens of thousands of atoms.

What is a polymer?

A macromolecule made from a chain of repeating or similar monomers.

What is a monomer?

A smaller building block used to construct a polymer.

CC: Are all macromolecules polymers?

No. All polymers are macromolecules, but not all macromolecules are polymers.

CC: What are the four major classes of biological macromolecules?

Carbohydrates, lipids, proteins, and nucleic acids.

CC: Which three major macromolecule classes are polymers?

Carbohydrates, proteins, and nucleic acids.

CC: Which major macromolecule class is NOT a polymer?

Lipids.

SEQ: What happens during dehydration synthesis?

Water is removed → smaller units join → a covalent bond forms → a larger molecule or polymer is built.

SEQ: What happens during hydrolysis?

Water is added → a bond is broken → a larger molecule or polymer is broken into smaller units.

CC: What is the easiest way to remember dehydration synthesis versus hydrolysis?

Dehydration BUILDS by removing water; hydrolysis BREAKS by adding water.

CC: What bond forms during dehydration synthesis?

A covalent bond.

If water is removed and smaller molecules are joined together, what process is occurring?

Dehydration synthesis.

If water is added and a larger molecule is broken apart, what process is occurring?

Hydrolysis.

What enzyme terminology did the professor mention in connection with these processes?

Dehydrogenases and hydrolases.

Do you need to prioritize memorizing the enzyme names?

Not unless the professor specifically says they must be memorized.

CC: What are the major functions of carbohydrates?

Energy storage/use and structural support.