Light Microscopy and Cell Biology Vocabulary

Vocabulary flashcards covering key terms from the lecture notes on light microscopy, the compound microscope, and the cell cycle.

Light microscopy

Any kind of microscope that uses visible light to observe specimens.

Compound light microscope

A microscope that uses a series of lenses (objective and ocular) to magnify specimens; the objective image is magnified again by the ocular lens.

Total magnification

The product of the magnification powers of the objective lens and the ocular (eye) lens.

Resolution

The ability of the lenses to distinguish two points as separate points.

Resolving power example (0.4 nm)

A resolving power value (e.g., 0.4 nm) indicates the minimum distance at which two points can be distinguished.

Refractive index

A measure of how much a medium bends (refracts) light.

Immersion oil

Oil used with oil-immersion objectives to reduce refraction and keep light from bending.

Ocular lens (eyepiece)

The lens you look through; it remagnifies the image formed by the objective lens (commonly 10X).

Objective lens

Primary lenses that magnify the specimen; common powers include 4X, 10X, 40X, and 100X.

4X (scanning) objective

Lowest-power objective used to scan a slide.

10X (low power) objective

Low-power objective providing moderate magnification.

40X (high power/high dry) objective

High-power objective magnification without oil immersion.

100X (oil immersion) objective

Oil-immersion objective that requires immersion oil for high-resolution viewing.

Condenser

Focuses light through the specimen.

Diaphragm

Controls the amount of light entering the condenser.

Illuminator

The light source of the microscope.

Coarse focusing knob

Large knob used for primary focusing.

Fine focusing knob

Smaller knob used for precise focusing.

Rheostat

Dimmer control for adjusting light intensity.

Revolving nosepiece

Rotating part that holds and changes objective lenses.

Stage

Platform that holds the microscope slide in place.

Line of vision

The path of light from the specimen to the observer’s eye.

Ocular lens magnification

Magnification provided by the eyepiece (commonly 10X).

Path of light

Route light follows from illuminator through condenser, specimen, objective, and to the ocular lens.

Plasma membrane

Flexible outer boundary of the cell.

Cytoplasm

Intracellular fluid containing organelles.

Nucleus

DNA-containing control center of the cell.

Cell theory

Cells are the structural and functional units of life; organisms arise from preexisting cells; structure and function are complementary.

Generalized cell parts

Plasma membrane, cytoplasm, and nucleus are present in human cells.

Interphase

Period from cell formation to division when the cell grows and carries out routine activities, including DNA replication in the S phase.

G0 phase

A stage where cells permanently cease dividing.

G1 phase

Gap 1; vigorous growth and metabolism.

S phase

DNA synthesis/replication occurs.

G2 phase

Gap 2; preparation for division.

Cell cycle

Series of changes a cell undergoes from formation to reproduction.

M phase

Mitotic phase; division occurs (mitosis and cytokinesis).

Mitosis

Nuclear division in which duplicated DNA is distributed to two daughter nuclei; followed by cytokinesis to form two identical daughter cells.

Prophase

First phase of mitosis; chromatin condenses into visible chromosomes, sister chromatids held at centromere; spindle forms and nucleolus disappears.

Metaphase

Chromosomes align at the metaphase plate with centromeres at the equator.

Anaphase

Centromeres split; sister chromatids separate and move toward opposite poles; poles are pushed farther apart.

Telophase

Chromosome sets arrive at poles and begin to de-condense; new nuclear membranes form; nucleoli reappear.

Cytokinesis

Division of the cytoplasm; cleavage furrow forms and two daughter cells are produced.

Centrosome

The organelle that organizes the spindle during mitosis; contains a pair of centrioles.

Centrioles

Paired structures within the centrosome involved in forming the spindle.

Mitotic spindle

Microtubule apparatus that separates chromosomes during mitosis.

Aster

Radial array of microtubules emanating from the centrosome.

Kinetochore

Protein structures at centromeres where microtubules attach to chromosomes.

Centromere

Region of a chromosome where sister chromatids are held together and where kinetochores attach.

Chromatid

One of two identical halves of a duplicated chromosome.

Sister chromatids

Two identical copies of a duplicated chromosome held together at the centromere.

Chromosome

DNA-containing structure that carries genetic information.

Chromatin

DNA-protein complex in the nucleus; uncondensed form during interphase.

Nucleolus

Site within the nucleus where ribosomal RNA synthesis occurs.

Nuclear envelope

Double membrane surrounding the nucleus.

Metaphase plate

Imaginary plane between poles where chromosomes align during metaphase.

Cleavage furrow

Indentation of the cell surface during cytokinesis, forming two daughter cells.

Cell diversity (example cell types)

Fibroblasts (connect parts/form linings), erythrocytes (carry gases), skeletal muscle cells (move parts), epithelial cells (form linings), fat cells (store nutrients), nerve cells (control body functions), macrophages (fight disease), sperm (reproduction), smooth muscle cells (move organs).