Microscopy and Cell Division

Flashcards covering key definitions related to light microscopy and the stages of cell division (mitosis and cytokinesis).

Light Microscopy

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

Ocular Lens (Eyepiece)

The microscope lens that remagnifies the image formed by the objective lens.

Objective Lenses

The primary lenses of a microscope that magnify the specimen.

Condenser

The part of a microscope that focuses light through the specimen.

Diaphragm

The part of a microscope that controls the amount of light entering the condenser.

Total Magnification

Calculated by multiplying the magnification power of the objective lens by the magnification power of the ocular lens.

Resolution

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

Refractive Index

A measure of the light-bending ability of a medium.

Immersion Oil

Used with high magnification objective lenses to keep light from refracting away from the objective, improving resolution.

Cell Diversity

Refers to the over 250 different types of human cells, which vary in size, shape, and subcellular components, leading to diverse functions.

Interphase

The period from cell formation to cell division, when a cell carries out its routine activities, grows, and prepares for cell division, with nuclear material in an uncondensed chromatin state.

Apoptosis

Programmed cell death, often described as 'cell suicide'.

G0 phase

A quiescent stage entered by cells that do not pass a G1 checkpoint or are terminally differentiated, thus not undergoing division.

M (Mitotic) Phase

The phase in the cell cycle during which cell division occurs, consisting of mitosis and cytokinesis.

Mitosis

The division of the nucleus, in which duplicated DNA is distributed to new daughter cells, ensuring each cell receives a full copy of replicated DNA.

Cytokinesis

The division of the cytoplasm, which begins during late anaphase and continues through mitosis, pinching the cell apart into two daughter cells.

Prophase

The first phase of mitosis, where chromatin coils and condenses into visible chromosomes, nucleoli disappear, and the mitotic spindle begins to form.

Sister Chromatids

Two identical copies of a chromosome held together by a centromere, prior to their separation during cell division.

Centromere

The region on a chromosome that links sister chromatids and where kinetochore proteins attach.

Mitotic Spindle

An assembly of microtubules that forms during prophase and aids in chromosome segregation during mitosis.

Kinetochore

Special protein structures at each chromosome's centromere where spindle microtubules attach.

Metaphase

The second phase of mitosis, where chromosomes cluster at the midline of the cell, with their centromeres precisely aligned at the metaphase plate.

Metaphase Plate

The imaginary plane midway between the poles of a dividing cell, along which chromosomes align during metaphase.

Anaphase

The third and shortest phase of mitosis, during which centromeres split, and sister chromatids separate, becoming individual chromosomes that move toward opposite poles of the cell.

Telophase

The final phase of mitosis, where chromosome movement stops, chromosomes uncoil to form chromatin, new nuclear membranes form around each chromatin mass, nucleoli reappear, and the spindle disappears.

Cleavage Furrow

A contractile ring of actin microfilaments that forms during cytokinesis and pinches the cell apart into two daughter cells.