Lab Exam 1

Question 1

Colony

Answer 1

A group of microbial cells visible to the naked eye.

Question 2

Role of nutrient agar

Answer 2

Solidify nutrient mixture. No digestible. Solid 25-37 degrees C. Allows colony morphology to be seen. Melts 100 and solidifies at 42.

Question 3

Total magnification

Answer 3

Objective x ocular

Question 4

Resolving power

Answer 4

550nm/(2xNA) numerical aperature. E.g. 4x 550nm/(2x0.1)= 2750nm

Question 5

Func of oil lens

Answer 5

Increases RP of 100x lens help with light refraction.

Question 6

Ocular lens

Answer 6

Lens u look through. Low magnification lens.

Question 7

Objective lens

Answer 7

Higher magnification. Magnifies slide

Question 8

Condenser lens

Answer 8

Converters the microscopes light into a single point on slide

Question 9

Iris diaphragm

Answer 9

Adjusts the amount of light hitting the specimen.

Question 10

Resolution

Answer 10

Clarity of microS. Smallest distance btw 2 nearby objects that can be distinguished.

Question 11

Single cell colony vs multi celled org

Answer 11

Multicellular have differentiated cells by structure and func

Question 12

Why r microbes hard to see when they r wet mount

Answer 12

No stain hard 2 distinguish

Question 13

Yeast vs mold

Answer 13

Yeast smaller and molds have diff strucrs like hyphae. Yeast smaller balls or clustered balls. Mold long twig like connected.

Question 14

Morphology

Answer 14

Coccus bacillus spirillum spirochete vibrio single diplo staphylo strepto irregular

Question 15

Gram + vs gram -

Answer 15

+ is purple and - is pink

Question 16

Eukaryotes vs prokaryotes

Answer 16

E- nucleus, organelles, linear DNA, variety. P- no nucleus, no organelles, circular DNA, Bacteria.

Question 17

Aseptic technique

Answer 17

Inoculate loop. Flame lip of test tube. Lip then flamed after culture added.

Question 18

Reasons for heat fixing

Answer 18

Cause cells to stick, kills cells, make cells more permeable to dye

Question 19

Differential stains

Answer 19

Gram, acid fast,

Question 20

Structural stains

Answer 20

Capsule endospores flagella

Question 21

Info from simple stain

Answer 21

Cell arrangement, morphology no show structural elements

Question 22

Simple stain

Answer 22

Dye dissociates in solution To form positive charged mcs and negative ion. Cytoplasm has negative charge attracts positive dye mcs. Splash water dye mcs retained.

Question 23

Why gram stain

Answer 23

Gram + respond differently bc have thicker PG walls. Gram + walls entrap the dye. The alcohol dissolves the gram - outer membrane and dye is released be have thin walls.

Question 24

False negative gram stain

Answer 24

Old culture or contaminated culture

Question 25

Pure cultures have

Answer 25

One colour, one morphology and arrangement.

Question 26

Acid fast bacteria

Answer 26

Mycobacterium tuberculosis

Question 27

Non microscopic motility

Test

Answer 27

Motility medium

Question 28

Why don’t dyes work on capsules

Answer 28

Capsule has no charge.

Question 29

Pathogenic Bacteria w/ spore

Answer 29

Clostridium tetanus- tetanus, bacillus anthracis- woolsorters Disease

Question 30

Negative stains

Answer 30

Cell background has a positive charge.