staining

an apparent structural detail that is caused by the processing of the specimen and is therefore not a legitimate feature of the specimen

bubbles loss of continuity in membranes distortion of organelles empty spaces in cytoplasm mesosomes

solid specimens viewed whole or cut into very thin slices cover slip over specimen e.g. hair, pollen, dust, insect parts, muscle, tissue, plants

specimen suspended in liquid (water/oil) cover slip placed at an angle e.g. aquatic samples and other living organisms

a wet mount but the cover slip is pressed down good for soft samples e.g. root tip squashes –> look at cell division (careful not to damage the cover slip)

edge of a slide is used to smear the sample creating a thin even coating on another slide cover slip places over sample e.g. blood smears to view blood cells

glass disc marked with fine scale of numbers but no units

what does a graticule enable you to do

to mark (a gauge or instrument) with standard scale of readings

a microscope slide with tiny ruler

increase contrast as different components within a cell take up stains to different degrees the increase in contrast allows components to become visible so they can be identified

negatively charged materials in cytoplasm

negatively charged materials in cytoplasm cell components

distinguish between to types of organisms or different organelles within an organism that would otherwise be hard to identify e.g. gram staining , acid-fast technique

used to separate bacteria into gram positive and gram negative based on thickness of cell wall

crystal violet stain is applied iodine is applied, fixes the dye washed with alcohol cells with thick walls retain stain, appear blue ; cells with thinner walls lose the blue/purple stain safranin dye is applied to gram negative, appear red

differentiate species of myobacterium from other bacteria

a liquid solvent is used to carry carbolfuchsin dye into the cell being studied cells are then washed with a dilute acid-alcohol solution myobacterium (acid-fast) are not affected by the acid-alcohal and retain the carbolfuchsin stain (bright red) other bacteria (non acid fast) lose the stain and are exposed to a methylene blue stain (blue)