A2.2 Cell Structure and Microscopy

Flashcards covering cell theory, organelle functions, microscopy types, calculations, and historical discoveries based on the A2.2 lecture transcript.

Mitochondria

The site of aerobic respiration, which releases energy.

Ribosome

The site of protein synthesis within a cell.

Cell membrane

The structure that controls the movement of substances in and out of the cell.

Cell Theory

A foundational understanding of life consisting of three components: all living things are composed of cells, the cell is the basic unit of life, and cells come from preexisting cells.

Emergent property

A property of life that arises as a consequence of interactions at the cellular level.

Binary fission

The method by which prokaryotic cells divide.

Inductive reasoning

A logical process of using specific observations to form a general conclusion, such as the development of cell theory from examining tissue specimens.

Deductive reasoning

A logical process of using a general premise to form a specific conclusion, such as predicting that a specific living organism is made of cells.

Magnification

How much larger an image appears compared to the real size of the object.

Resolution

The smallest interval distinguishable by a microscope, which corresponds to the degree of detail visible in an image.

Field of view (FOV)

The diameter of the area visible through the microscope.

Wet mount

A slide preparation where a drop of water is used to suspend a specimen between the slide and cover slip to observe motile organisms or samples needing staining.

Stains

Chemical substances that bind to specific structures within a sample to make them show more clearly under a microscope.

Iodine

A stain used to identify starch, which appears brown or blue-black, and glycogen, which appears red.

Methylene Blue

A stain used to identify cell nuclei and DNA.

Gram Stain

A staining method that divides bacteria into Gram positive (purple) or Gram negative (pink) based on cell wall composition.

Micrometre ($\mu m$)

A unit of length equal to $1/1000^{th}$ of a millimetre or $10^{-6}$ metres.

Nanometre (nm)

A unit of length equal to $1/1000^{th}$ of a micrometre or $10^{-9}$ metres.

Actual Size Formula

$$\text{Actual size} = \frac{\text{image size}}{\text{magnification}}$$

Robert Hooke

The scientist who discovered cells in 1663.

Anton von Leeuwenhoek

The scientist who discovered unicellular organisms in 1674.

Matthias Schleiden

The scientist who realized in 1838 that all plants are made of cells.

Theodore Schwann

The scientist who realized in 1839 that all animals are made of cells.

Rudolf Virchow

The scientist who proposed in 1855 that all cells come from other cells.

Transmission electron microscope (TEM)

A microscope that transmits a beam of electrons through a specimen to produce a 2D image, providing excellent resolution (0.5 nm) and high magnification (up to 500,000X).

Scanning electron microscope (SEM)

A microscope that sends a beam of electrons across the surface of a specimen to produce 3-D images by collecting reflected electrons.

Immunofluorescence

A technique using fluorescently stained antibodies to bind to target proteins, allowing them to be located and tracked within a cell.

Freeze-fracture

A sample preparation technique for electron microscopy involving rapid freezing and physical fracturing of cells to reveal internal planes, such as the center of membranes.

Cryogenic electron microscopy

A recent advancement used to determine the structure of molecules at near atomic-level resolution by freezing specimens at very low temperatures and using computer analysis.

Photomicrograph

A photograph taken of a microscope image, also known as a micrograph.