Basics of Cell Biology & Microscopy Techniques

Vocabulary practice cards reviewing essential cell chemistry, macromolecular building blocks, the Central Dogma, and light/fluorescence microscopy concepts from the lecture.

Major Elements of Living Organisms

Carbon (C), hydrogen (H), nitrogen (N), and oxygen (O), which together make up $96\%$ of any organism's mass.

Central Dogma

The core principle shared by all cells describing the flow of genetic information: $\text{DNA} \rightarrow \text{RNA} \rightarrow \text{Protein}$ through replication, transcription, and translation.

Noncovalent Interactions

Four types of weak interactions that help molecules come together in cells: electrostatic attraction, van der Waals attraction, hydrophobic force, and hydrogen bonds.

Hydrogen Bond

A special type of noncovalent bond formed between an electronegative donor atom (such as oxygen or nitrogen) bound to hydrogen and an acceptor atom.

Sugars

Small organic building blocks of the cell that covalently bond to form polysaccharides and oligosaccharides.

Fatty Acids

Small organic building blocks of the cell that combine to form fats and membrane lipids.

Amino Acids

Small organic building blocks of the cell that covalently link via peptide bonds to form proteins.

Nucleotides

Small organic building blocks of the cell that covalently link to form nucleic acids such as DNA and RNA.

Resolution Limit of Light Microscopy

The maximum resolving power achievable by conventional light microscopes, which is approximately $200\,\text{nm}$ ($0.2\,\mu\text{m}$).

Objective Lens

The magnifying lens in a compound light microscope that collects light directly from the specimen and magnifies it.

Eyepiece Lens

The lens in a compound microscope that further magnifies the light coming from the objective lens and focuses the image for viewing or digital capture.

Transmission Microscopy

A microscopy approach where transmitted light must pass through the specimen en route to collection by the lenses.

Fluorophore

A fluorescent molecule that absorbs light at a specific wavelength and emits light at a longer wavelength when returning to its ground state.

Immunofluorescence

A staining method that uses antibodies conjugated to fluorophores to specifically bind and visualize targeted antigens inside cell samples.

Green Fluorescent Protein (GFP)

A fluorescent protein originally isolated from the jellyfish Aequorea victoria that can be expressed in cells to tag and track biological structures.

Confocal Microscopy

An optical imaging technique that pairs high-intensity laser illumination with pinhole apertures to reject out-of-focus light, producing sharp images of subcellular structures.

DAPI (4',6-Diamidino-2-Phenylindole)

A fluorescent stain that binds directly to cellular DNA, exhibiting excitation at approximately $360\,\text{nm}$ and emission at approximately $460\,\text{nm}$.

Widefield vs. Confocal Imaging

Comparison showing widefield microscopy (A), which collects out-of-focus background light, versus confocal microscopy (B), which uses a pinhole to exclude out-of-focus light and reveal crisp subcellular details.

Direct vs. Indirect Immunofluorescence

Diagram showing direct immunofluorescence using a single fluorophore-labeled antibody (left), compared to indirect immunofluorescence using an unlabeled primary antibody detected by fluorophore-labeled secondary antibodies (right).