BIOL 1017: Cell Biology - Lecture 1: The Cell Theory

Vocabulary flashcards covering core topics from Lecture 1: characteristics of living organisms, the Cell Theory, thermodynamics and systems, the Central Dogma, cell size limits, virus structure, and microscopy techniques.

Entropy

The tendency toward disorder that exists naturally in the physical world.

The Cell Theory

A foundational biological theory formulated in the 19th century stating that all living things are composed of cells, the cell is the structural and functional unit of living organisms, and all cells arise from the division of pre-existing cells.

Spontaneous Generation

The disproven concept that life can arise spontaneously from non-living matter, which is contradicted by the principle that all cells come from pre-existing cells.

Gene

A fragment of genetic information in DNA corresponding to one protein.

Central Dogma of Molecular Biology

The framework describing the directional flow of genetic information: DNA replicates itself, DNA is transcribed into RNA, and RNA is translated into an amino acid sequence forming a protein.

Input (System)

Resources that are taken or received by a system from its external environment.

Throughput (System)

The internal process of conversion or transformation of resources within a system.

Output (System)

The work performed by a system that is exported back into its environment.

Feedback (System)

A continuing source of information regarding a system's relationship with the external environment, used to make necessary adjustments to survive and grow.

Chemical Work (Cellular)

Cellular activity involving the synthesis of cellular materials and macromolecules.

Osmotic Work (Cellular)

Cellular work required to control appropriate concentration gradients within the cell and relative to its external environment.

Mechanical Work (Cellular)

Cellular work responsible for physical movement and locomotion, such as through cilia and flagella.

Regulatory Work (Cellular)

Cellular work managing the regulation of synthesis and interaction between macromolecules.

Surface Area to Volume Ratio (SA:V)

A mathematical relationship that decreases as a cell increases in volume; surface area determines exchange rates of raw materials and wastes, while volume determines internal chemical activity rates.

Viruses

Non-cellular entities containing protein and nucleic acid, lacking membranes, a nucleus, and protoplasm, which exhibit characteristics of life only while reproducing inside a host cell.

Bacteriophage Structure

A virus structure comprising a head (capsule) containing nucleic acid, attached to a tail, end plate, and tail fibers used for host attachment.

Resolution (Microscopy)

The minimum distance two distinct objects can be separated and still be distinguished as two individual objects.

Limit of Resolution of Human Eye

The resolving power limit of the unaided human eye, equal to $200\,\mu\text{m}$.

Limit of Resolution of Light Microscope

The resolving power limit of a standard light microscope, equal to $0.2\,\mu\text{m}$.

Limit of Resolution of Electron Microscope

The resolving power limit of an electron microscope, equal to $2\,\text{nm}$ ($0.002\,\mu\text{m}$).

Bright-Field Microscopy

A standard light microscopy method where light passes directly through a cell, producing low contrast and minimal detail unless natural pigments or stains are present.

Dark-Field Microscopy

A light microscopy technique using an opaque disk to block direct light, forcing light to strike the specimen at oblique angles so diffracted/refracted light forms a bright image on a dark background.

Fluorescence Microscopy

A technique where cellular molecules or applied dyes are excited by light energy to re-emit longer-wavelength fluorescent light, enabling specific structure visualization.

Phase-Contrast Microscopy

A light microscopy technique that increases image contrast by emphasizing differences in the refractive index (light-bending capacity) across cell structures.

Iodine Stain

A chemical stain used in light microscopy to dye starch grains blue.

Haemotoxylin Stain

A microscopic stain used to color cell nuclei violet-brown.

Eosin Stain

A histological stain used to color cell cytoplasm and membranes red-pink.

Crystal Violet Stain

A stain used in microscopy to color the cell walls of Gram-positive bacteria dark purple.

Phloroglucinol-HCl Stain

A chemical stain used in plant histology to color sclerenchyma tissue red.