AP Biology Unit 1 - Chemistry of Life

Water & Hydrogen Bonding & Marcomolecules

Cohesion

A hydrogen bond between the **same** molecules or two water molecules

Adhesion

A hydrogen bond between two **different** molecules, such as water and an amino acid

Surface Tension

A phenomenon, resulting from **cohesive** properties, when hydrogen bonding occurs between water molecules at the surface (leaves of aquatic plants depend on it for better access to sunlight during photosynthesis)

High Solvency

Resulting from **adhesive** properties, water’s ability to dissolve other molecules (allows materials to dissolve and be easily accessed by cells so living systems can obtain nutrients from their environment)

Ability of Ice to Float

Water’s **cohesive** property and **unique hydrogen bond** interaction make water as a solid more dense (allows aquatic organisms to thrive in cold conditions since only the surface of the water gets frozen over)

High Heat Capacity

Water’s **cohesive** ability to absorb an abundance of thermal energy and resist sudden temperature changes (sea animals depend on it to maintain their body temperature)

Capillary Action

The forces of **cohesion**, which causes water to stick together, and **adhesion**, which cause water droplets to stick to stem walls and be pulled upward during transpiration (so plants can access water)

Macromolecule

A molecule that is necessary to sustain life- **Nucleic Acids, Proteins, Carbohydrates, and Lipids**

Monomer

A molecule that makes up a polymer

Polymer

A macromolecule made up of monomers

Dehydration Synthesis

**Forms covalent bonds** by joining monomers into polymers and releasing water as a byproduct (⬠ + ⬠ → ⬠⬠ + H20)

Hydrolysis

**Cleves covalent bonds** by breaking polymers into monomers and adding water subcomponents to each monomer (⬠⬠ + H20→ ⬠ + ⬠ )

Nucleic Acid

A polymer/macromolecule present in **DNA and RNA**, made out of **nucleotides**

Nucleotides

Nucleic Acid’s **monomer**- contains a phosphate group, nitrogen base, and 5-carbon sugar

What elements does nucleic acid contain?

Carbon, Nitrogen, and Phosphorus

What is the directionality of nucleotides?

Characterized by its anti-parallel 3’ hydroxyl ends and 5’ phosphate ends, with __2 hydrogen bonds__ between Adenine and Thymine and __3 hydrogen bonds__ between Guanine and Cysostine. During synthesis, nucleotides can only be added to the 3’ end.

Pyrimidines Family of Nitrogenous Bases

**Cytosine, thymine, and uracil**- have a single six-membered ring

Purines Family of Nitrogenous Bases

**Adenine and guanine**- have a six-membered ring fused to a five-membered ring

What influences the structure and function of nucleic acid polymers?

1. A change in nucleotides will lead to a change in its **function**, since biological information is stored in its sequence.
2. and in **stability**, since the amount of hydrogen bonds between nitrogen base pairs affects how stable the molecule’s structure is (the more hydrogen bonds, the more stable)

What are the similarities between DNA and RNA?

Both are comprised of a **5-carbon sugar, phosphate group, and nitrogenous base**, their nucleotides are connected with **covalent bonds**, and they have the same **directionality**

What are the differences between DNA and RNA?

**Sugars** (DNA = deoxyribose, RNA = ribose), **4th Nitrogenous Base** (DNA = thymine, RNA = uracil), **Number of Strands** (DNA = double-stranded, RNA = single-stranded)

Proteins

A polymer/macromolecule made out of **amino acid**

Amino Acids

Protein’s **monomer**- Comprised of a center carbon with an amino terminus on one end and carboxyl end on the other, and R group attached to the center carbon

R Group

A group of atoms attached to the central carbon in an amino acid, that **can change the chemical property of proteins to hydrophobic, hydrophilic, or ionic**

What elements does protein contain?

Carbon and Nitrogen

Polypeptide

A primary structure of proteins and sequence of amino acids bonded together

Peptide Bond

A **covalent bond** formed between the carboxyl group of one amino acid the amino group of another

What is the directionality of amino acids?

The **linear chains of amino acids** gives directionality with an amino terminus and carboxyl terminus

Primary Structure

The first element of protein structure, characterized by a **non functional sequence of amino acids (polypeptides) held together with peptide bonds**

Secondary Structure

The second element of protein structure, when amino acid chains **fold/twist into alpha-helices and beta-shee**ts

Tertiary Structure

The **3D functional form for most proteins**, who’s R Group is stabilized. **The protein bends** since nonpolar (hydrophobic) acids fold inwards and polar (hydrophilic acids fold outside

Quaternary Structure

The final element of protein structure for some proteins, that is comprised of **multiple polypetite units togethe**r and usually functions as hemoglobin

Chaperones

Protein molecules that assist the proper folding of other proteins

What influences the structure and function of protein polymers?

**A change in polarity in the R Group** can affect the direction the protein bends in and change its function to receive different molecules

Carbohydrates

A polymer/macromolecule present in **starches and sugars**, made out of **monosaccharides** or “simple sugars”, with a **linear or branched structure**

Monosaccharides or “Simple Sugars”

Carbohydrates’ **monomer**- (CH2O)n, a carbon chain bonded to two hydrogens and one oxygen

What element do carbohydrates contain?

Carbon

Polysaccharides

A carbohydrate polymer, formed of **monosaccharides**

Glycosidic Bond

A **covalent bond** formed between carbohydrate or sugar molecules

What is the directionality of monosaccharides?

The directionality is decided by **the assembly of polysaccharides, connected by glycosidic bonds**

What influences the structure and function of carbohydrate polymers?

The **orientation of monosaccharides** and **type of sugar monomer** determine their function

Lipids

A polymer/macromolecule present in **fats**, made out of **fatty acid and glucose**

Fatty Acid & Glucose

Lipid’s non-polar **monomer** (does not have true monomer), comprised of a straight chain of carbon atoms, hydrogen atoms, and a carboxyl group

What element do lipids contain?

Carbon and Phosphorus

Phospholipids

Membrane lipids **with hydrophilic and hydrophobic regions** that decide their interactions with other molecules

What influences the structure and function of lipid polymers?

The **saturation** __(saturated= single bonds, unsaturated= double bonds)__ of fatty acids determines the structure and function of lipids