lab 20 goals and objectives: exercise 58: bacterial counts on foods count colonies: calculate...

Lab 20 Goals and Objectives:

Exercise 58: Bacterial Counts on FoodsCount colonies: calculate CFU/gram (meat, spinach) or CFU/ml (milk)

*Remember, plates of 30-300 only! Share data, get class averagesExercise 59: Bacteriological Examination of Water

Determine the MPN (Table 59.1) coliforms /100mlStreak one positive tube for isolation on EMB agar

Exercise 60: The Membrane Filter MethodCheck filters for coliforms: (examples of Escherichia and

Enterobacter on EMB provided to demonstrate appearance of coliforms)

Count coliforms and compare to MPN from Ex 59Biotechnology Practice ExerciseEach pair get: Two Pipettors, Box of tips, Tube of colored water, Two

squares of parafilm: Practice pipetting 5µl water: make a 3 X 3 5µl drop pattern on the parafilm and check that all drops look the same size

EDVOKIT#300: Blue/White Cloning of a DNA FragmentWork in five groups total (double up with another pair?)Set up the ligation (tube 1) and ligation control (tube 2) reactions according to directions on pg 11. When done, put in rack to incubate.

To “clone a gene”: means to copy the gene from its original natural genomic source and to put it into a plasmid/vector for expression (protein product) or other experimental use.

EDVO page 4

EDVO page 5

Restriction enzymes cut DNA at certain base sequences leaving “sticky ends” that “want” to ligate with other complementary sticky ends.

Vector + gene we want to clone + ligase

~incubate~

Two possible products:-gene ligated into

vector -vector religated

without gene

Ligation

Transformation

EDVO page 6

Experiment Overview

Biotechnology ToolsMicropipettor Practice

Good consistent pipetting!

Need more practice!

- touch tip to surface when dispensing

- “blow out” sample and pull away before letting go of plunger

EDVO page 11

Set up ligation