Biomolecules, Proteins, Nucleic Acids, and Cell Theory Flashcards

Vocabulary practice flashcards covering proteins, nucleic acids, cell theory history, and membrane phospholipids based on lecture notes.

Amino Acid

The monomer unit of proteins consisting of a central carbon atom bonded to a hydrogen atom, an amino group, a carboxyl group, and a variable side chain (R group).

Polypeptide

A polymer of amino acids joined together in a specific linear sequence by peptide bonds.

Peptide Bond

The covalent bond formed between the carboxyl group of one amino acid and the amino group of another through a condensation reaction.

N-terminus

The amino end of a polypeptide chain possessing a free amino group.

C-terminus

The carboxyl end of a polypeptide chain possessing a free carboxyl group.

Primary Structure

The specific sequence of amino acid residues comprising a polypeptide chain.

Secondary Structure

The localized, repeated coiling or folding of a polypeptide chain backbone stabilized by hydrogen bonds between backbone atoms.

$\alpha$-helix

A helical secondary structure in proteins stabilized by hydrogen bonding between peptide backbone atoms.

$\beta$-pleated sheet

A secondary structure in proteins formed by side-by-side polypeptide chain segments linked by hydrogen bonds between backbone strands.

Tertiary Structure

The overall three-dimensional shape of a polypeptide resulting from interactions between side chains (R groups).

Disulfide Bridge

A covalent bond formed between sulfur atoms of cysteine amino acid residues that stabilizes protein tertiary structure.

Quaternary Structure

The overall protein structure resulting from the association and aggregation of two or more polypeptide chains.

Denaturation

The process in which a protein loses its functional spatial conformation and native structure due to external stress or chemical factors.

Nucleotide

The fundamental monomer of nucleic acids, composed of a nitrogenous base, a pentose sugar, and a phosphate group.

Pyrimidine

A category of nitrogenous bases characterized by a single six-membered ring, including Cytosine (C), Thymine (T), and Uracil (U).

Purine

A category of nitrogenous bases characterized by a six-membered ring fused to a five-membered ring, including Adenine (A) and Guanine (G).

Phosphodiester Linkage

The covalent linkage connecting adjacent nucleotides in a polynucleotide chain between the sugar of one nucleotide and the phosphate group of another.

Cell Theory

The unified biological principles stating that all organisms are composed of one or more cells, the cell is the basic unit of life, and all cells arise only from pre-existing cells.

Robert Hooke

The scientist who invented a crude microscope $(30\times)$ in 1665 and was the first to observe small compartments in cork.

Anton van Leeuwenhoek

The scientist who developed an improved microscope $(300\times)$ in the 1670s and was the first to observe living microbes.

Louis Pasteur

The scientist who performed the 1862 swan-necked flask experiment demonstrating that cells arise only from pre-existing cells and not by spontaneous generation.

Amphipathic

Possessing both hydrophilic (water-attracting) and hydrophobic (water-repelling) regions on the same molecule.

Phospholipid

An amphipathic lipid made of glycerol attached to two fatty acid tails and a hydrophilic phosphate head, forming membrane structures in aqueous environments.

Selectively Permeable

The property of biological membranes that allows controlled passage of specific substances while blocking others.

Triglyceride

A lipid formed by combining one molecule of glycerol with three fatty acid chains.

Steroid

A category of lipids defined by a carbon skeleton made up of four interconnected rings.