Biochemistry and Macromolecules Lecture Flashcards

Flashcards reviewing key biochemistry concepts from the lecture, including protein structure, nucleic acids, ATP energy conversion, carbohydrates, isomers, dehydration synthesis, and lipid bilayers.

What part of an amino acid determines its specific identity and properties?

The side chain (also known as the R group) determines what kind of amino acid it is.

What are essential amino acids?

Essential amino acids are those that the human body cannot synthesize on its own and must be obtained directly from dietary food sources.

How do polar amino acid side chains affect the folding of a polypeptide?

Polar side chains contain positive and negative regions that form hydrogen bonds, causing the polypeptide chain to naturally bend and fold.

What defines the primary structure of a protein?

The primary structure is the specific sequence or order of amino acids linked together in a polypeptide chain.

What are the four levels of protein structure described in the lecture?

Primary (amino acid sequence), Secondary (helices or pleated sheets), Tertiary (3D bending and folding of secondary structures), and Quaternary (assembly of two or more polypeptide subunits).

What are the three main chemical components that make up a nucleic acid subunit?

A phosphate group, a sugar (ribose or deoxyribose), and a nitrogenous base (nucleotide).

Which nitrogenous bases pair together in DNA, and how many hydrogen bonds hold each pair together?

Adenine ($\text{A}$) pairs with Thymine ($\text{T}$) using two hydrogen bonds, and Guanine ($\text{G}$) pairs with Cytosine ($\text{C}$) using three hydrogen bonds.

Why can two double-ring nitrogenous bases not pair with each other inside DNA?

Pairing two double-ring structures would create bulges in the DNA molecule, destabilizing the double helix structure.

What chemical components make up a molecule of adenosine triphosphate (ATP)?

A ribose sugar, an adenine base, and three attached phosphate groups.

Why does breaking the phosphate bonds in ATP release energy for the cell?

The oxygen atoms on the phosphate groups carry negative charges that repel each other; breaking these bonds releases stored potential energy that the cell can use for work.

What is the general chemical formula for carbohydrates?

$\text{C}(\text{H}_2\text{O})_n$, indicating a backbone composed of carbon, hydrogen, and oxygen atoms.

How does the structural form of glucose change between a dry state and an aqueous solution?

In a dry crystallized form, glucose exists as a linear chain, whereas in an aqueous solution, it forms a ring structure.

What are chemical isomers, such as glucose and galactose?

Isomers are compounds that share the exact same chemical formula (e.g., $\text{C}_6\text{H}_{12}\text{O}_6$) but have different three-dimensional structural arrangements.

What chemical process links two monosaccharides together to form a disaccharide?

Dehydration synthesis, a reaction that forms a covalent bond between two sugars by removing two hydrogen atoms and one oxygen atom to produce a molecule of water ($\text{H}_2\text{O}$).

Which specific monosaccharides combine to form sucrose, lactose, and maltose?

Sucrose is formed by glucose and fructose; lactose is formed by glucose and galactose; maltose is formed by two glucose molecules.

What atomic composition distinguishes lipid hydrocarbon tails from carbohydrates?

Lipid hydrocarbon tails consist almost entirely of carbon and hydrogen atoms, lacking the abundant oxygen atoms found in carbohydrates.

How do phospholipids arrange themselves to form a cellular membrane?

They form a phospholipid bilayer where the hydrophilic phosphate heads face outward toward water and the hydrophobic hydrocarbon tails face inward away from water.

How do unsaturated fatty acids differ structurally from saturated fatty acids?

Saturated fatty acids have straight chains with single carbon-carbon bonds and two hydrogens per carbon, whereas unsaturated fatty acids contain double carbon bonds ($\text{CH}=\text{CH}$) that create a kink in the tail.