lab final microscopy/ classification

Know the origins of the microscope

• the simplle microscope was invented around 1600 by Zacharias janssen

• In 1676, Antoni van Leeuwenhoek first observed and described mircoorganisms, calling them “animalcules”

• his discoveries and detailed records laid the foundation for modern microbiology

what are parts of the bright-field microscope

• ocular lens

• objective lenses

• stage platform & clips

• condenser & fine adjustment knobs

• light source

what do ocular lens(10x) do?

magnifies the image 

what are the objective lenses?

4x (scanning), 10x (low), 40x (high), 100x (oil immersion)

what do stage platform & clips do?

hold and secure the slide

what do condenser & iris diaphragm do?

focus and control light

what do the coarse & fine adjustment knobs do? 

bring the specimen into focus 

what do the light source do?

illuminates the specimen

what is the calculation for scanning lens?

10 × 4 = 40x

what is the calculation for low power lens?

10 × 10 = 100x 

what is the calculation for high power lens?

10 × 40 = 400x

what is the calculation for oil immersion lens?

10 × 100= 1000x

what is the oil immersion lens used for? 

viewing very small microorganisms (like bacteria) at 1000x total magnification 

how does oil immersion lens work?

• a drop of oil ( same refractive index as glass) is placed between the slide and the lens

• prevents light from bending (refraction) and increases resolution

• produces a clearer, brighter image

what are the proper microscope steps (part 1)?

• always carry with two hands- one on the arm, one under the base 

• never drag or scoot the microscope; gently lift it 

• keep cords away from the work area to avoid accidents 

• use lens paper only for cleaning lenses 

• start with the scanning lens (4x) before switching to higher magnifications 

what are the proper microscope care (part 2)?

• uses coarse focus first, then fine focus to sharpen the image

• never use coarse focus with high- power or oil immersion lenses

• clean oil from the lens before storage

• turn off and unplug the microscope after use

• store the microscope carefully with the scanning lens in place 

what are the 3 basic bacterial shapes? 

• coccus (plural: cocci) 

• bacillus (plural: bacilli) 

• spirillum (plural: spirilla) 

what is the shape of a coccus and a example?

• shape: round or spherical

• example appearance under microscope: small, circular cells that may appear alone, in pairs, chains, or clusters depending on the type

what is the shape of a Bacillus and example?

• shape: rod-shaped or cylindrical

• example appearance: straight or slightly curved rods; they may be single, in pairs, or form chains

what is the shape of Spirillum and example?

• shape: spiral, curved, or corkscrew- shaped 

• example appearance: wavy or spiral cells with distinct twists or curves 

what are the arrangements for cocci?

• diplococci

• streptococci

• tetrads

• sarcinae

• staphylococci

what is diplococci?

pairs of spherical cells that remain attached after one division

what is streptococci? 

chains of spherical cells formed after repeated divisions in one place 

what is tetrads?

groups of four cocci that form when division occurs in two planes

what is sarcinae?

cube- like packets of eight cells formed by division in three planes

what is staphylococci? 

irregular clusters or grape- like groups formed by division in multiple planes 

What. are the bacilli arrangement?

• diplobacilli

• streptobacilli

what is diplobacilli?

two- rod shaped cells joined together after division

what is streptobacilii? 

chains of rod-shaped cells that remain attached end to end