Biochemistry and Cell Biology Lecture Flashcards

Vocabulary flashcards covering macromolecule structures, nucleic acids, protein folding, lipid characteristics, membrane properties, and membrane transport systems based on the lecture transcript.

Proteins

True polymers consisting of long chains of amino acid monomers linked by peptide bonds.

Carbohydrates

Complex carbohydrates (polysaccharides like starch and cellulose) that are true polymers made of repeating monosaccharide (simple sugar) monomers.

Nucleic Acids

True polymers (polynucleotides like DNA and RNA) constructed from repeating nucleotide monomers.

Lipids

Diverse, hydrophobic molecules that do not consist of repeating monomers and are therefore not considered polymers.

Polymers

Large molecules made up of repeating subunits called monomers.

Central Dogma

The flow of genetic information in biological systems: $\text{DNA} \rightarrow \text{RNA} \rightarrow \text{Polypeptide}$.

Phosphodiester Bond

A covalent bond formed by a reaction between the $3'\text{-OH}$ of one nucleotide and the $5'\text{-P}$ of the next nucleotide, releasing pyrophosphate.

Amphipathic Molecules

Molecules that possess both a polar and a non-polar end.

Purines

Double-ring nitrogenous bases consisting of Adenine (A) and Guanine (G).

Pyrimidines

Single-ring nitrogenous bases consisting of Cytosine (C), Thymine (T), and Uracil (U).

Nucleoside

A molecule consisting of a nitrogenous base attached to a sugar (ribose or deoxyribose).

Nucleotide

A monomer consisting of a nitrogenous base, a sugar (ribose or deoxyribose), and 1, 2, or 3 phosphate groups (mono, di, or tri).

Adenosine Triphosphate (ATP)

A nucleotide that functions to generate cellular energy.

Guanosine Triphosphate (GTP)

A nucleotide involved in protein synthesis.

Cyclic AMP (cAMP)

A nucleotide that serves as a messenger in signal transduction.

Louis Pasteur

Scientist who disproved spontaneous generation by demonstrating that cells derive from pre-existing cells.

Miller-Urey Experiment

An experiment demonstrating that complex organic molecules could have arisen from $H_2O$ and simple atmospheric components.

Peptide Bond

A bond joining amino acids formed through a condensation reaction that possesses partial double bond character.

Oligopeptide

Short polymers made of $20$ or fewer amino acids.

Polypeptide

Longer polymers of amino acids featuring an amino terminus and a carboxyl terminus.

Primary Structure

The linear sequence of amino acids in a protein held together by peptide bonds.

Secondary Structure

Protein structural elements ($\alpha$ helices and $\beta$ pleated sheets) formed by hydrogen bonds between $N-H$ and $C=O$ groups of the polypeptide backbone.

Tertiary Structure

The 3D macromolecular folding of a single polypeptide chain optimized by side chain interactions.

Quaternary Structure

Protein structural assembly consisting of $2$ or more independent polypeptide chains.

Chaperones

Proteins that help new proteins fold for the first time and assist older proteins in re-folding.

Protein Denaturation

The unfolding of a protein caused by heat, pH changes, or chemicals that destroys its biological function.

Carotenoids

Light-absorbing pigments that function in photosynthesis and serve as vitamin precursors.

Steroids

Lipids composed of linked hydrocarbons that act as hormones and hormone precursors.

Transmembrane Protein

An integral membrane protein containing a transmembrane domain that extends through the lipid bilayer region.

Peripheral Membrane Protein

A membrane protein that interacts with the inner leaflet or surface of the membrane without spanning the lipid bilayer.

Integral Membrane Protein

A protein partially or fully embedded within the lipid bilayer, which can be single or multi-pass.

Lipid Rafts

Specialized microdomains that move around fluidly within the cell membrane.

Lipoproteins

Complexes responsible for transporting lipids throughout biological systems.

Conformational Changes

Structural alterations involving a change in the configuration of a protein without changing its overall basic structure.

Tight Junctions

Cell junctions that form seals to prevent substances from passing between cells and maintain separation between apical and basal surfaces.

Desmosomes

Cell junctions that act like staples holding neighboring cells together to provide strength and resist physical stretching stress.

Gap Junctions

Communication channels connecting the cytoplasm of neighboring cells, allowing small molecules and ions to pass directly.

Diffusion

The movement of particles from high to low concentration driving toward equilibrium with no net change in distribution once balanced.

Passive Transport

The movement of substances down a concentration gradient (from high to low) that requires no ATP.

Active Transport

The movement of substances against a concentration gradient (from low to high) that requires ATP.

Aquaporins

Protein channels discovered by Peter Agre that facilitate the rapid movement of water across membranes.

Sodium-Potassium Pump

An active transport pump that uses ATP to move $3\text{ Na}^+$ ions out of the cell and $2\text{ K}^+$ ions into the cell against their concentration gradients.

Secondary Active Transport

A saturable transport process that uses the $Na^+$ gradient established by the $Na^+/K^+$ pump to move another substance uphill against its gradient without directly using ATP.