BIOLOGY 173 Study Guide - Midterm Guide: Glycolysis, Dietary Fiber, Ethanol Fermentation

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School
Department
Exam 1 Review: Bio 173 Research Section
University of Michigan Winter 2017
Baxter & Schmidt
MICROBIAL CULTIVATION
1) Theory behind spread/streak plating and when to use them
Spread Plating involves spreading a small volume of sample evenly over the surface of an
agar plate
Theory is that each viable cell from the sample will grow and divide to produce one colony
on the agar medium
Report given sample count as the number of colony forming units (CFUs)
To be successful, you must obtain a countable number of colonies (a good range is 25-250
CFUs); must use serial dilutions to get @ least one plate with optimal CFUs
Streak Plating is an easy way to obtain pure cultures
Theory is that you will create a region on an agar plate where bacteria are so dilute that
isolated colonies develop
2) What does it ea for edia to e seletie? Ho do you ake it seletie?
Selective Media only allow certain types of organisms to grown and they inhibit the growth
of other organisms
Many ways to make media selective, including: limiting the carbon source, adding
dyes/antibiotics/specific inhibitors
3) What does it ea for edia to e differetial?
Differential Media are used to differentiate closely related organisms or groups or
organisms
With presence of certain dyes or chemicals, the organism will produce characteristic
changes or growth patterns used for identification
4) Know how to make serial dilutions
Serial Dilutions are intended to reduce the concertation of cells in each subsequent dilution
until the concentration of cells will yield countable colonies; usually use a 10-fold dilution
5) Calculate CFUs per mL
CFUs/mL= (# of colonies )÷ (dilution factor * volume plated mL)
6) What are characteristics of bacterial colonies that can be used to distinguish species?
Size, Color, Shape, Texture
DNA EXTRACTION AND PCR
1) What is the purpose of the microbeads used during DNA extraction?
Shredding DNA into many small particulates
2) What is the purpose of the spin filter used during DNA extraction?
DNA is selectively bound to the silica membrane in the spin filter device. Contaminants pass
through the silica filter membrane, leaving only the DNA bound to the membrane
3) Understand how PCR works
Sample is heated to denature DNA (separates into 2 strands)
An enzyme, Taq Polymerase, synthesizes 2 new strand of DNA, using original strands as
templates and primers results in the duplication of original DNA
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Process repeats 30-40 times to obtain more than 1 billion copies of the DNA
4) Why do we run PCR products on a gel?
Helps analyze reaction quality; electrophoresis also reveals the size of product band and
how much of the band was produced
5) Understand how to use a DNA Ladder to determine the size of DNA on a gel
The ladder serves as a baseline to which you can compare your PCR products. Contains a set
of known DNA fragment sizes and is used to determine size/quantity of PCR product
OTHER LAB TECHNIQUES
1) Know how to use a micro-pipette
Go to 1st stop for drawing UP liquid and go to 2nd stop for EJECTING liquid
Do NOT adjust beyond limits; heavy line is the decimal point
2) Know how to generate a standard curve and use it to calculate an unknown
Use date, generate graph on computer using data, plug in unknown for appropriate variable
3) Be able to interpret results from the potassium iodine starch assay
(StarchOriginal StarchHuman) ÷StarchOriginal = % degraded
WHO/WHAT/WHERE IS THE GUT MICROBIOME
1) Recognize the environmental characteristics of the gut microbiome
Changes throughout GI tract
Includes pH, bacterial load, oxygen concentration, nutrients
2) Be familiar with the structure of the intestinal barriers
3) Understand the levels of taxonomy
Domain Bacteria
Kingdom Bacteria
Phylum Proteobacteria
Class Gammaproteobacteria
Order Enterobacteriales
Family Enterobacteriaceae
Genus Escherichia
Species E. coli
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Document Summary

Microbial cultivation: theory behind spread/streak plating and when to use them. Spread plating involves spreading a small volume of sample evenly over the surface of an agar plate. Theory is that each viable cell from the sample will grow and divide to produce one colony on the agar medium. Report given sample count as the number of colony forming units (cfus) To be successful, you must obtain a countable number of colonies (a good range is 25-250. Cfus); must use serial dilutions to get @ least one plate with optimal cfus. Streak plating is an easy way to obtain pure cultures. Selective media only allow certain types of organisms to grown and they inhibit the growth of other organisms. Differential media are used to differentiate closely related organisms or groups or organisms. With presence of certain dyes or chemicals, the organism will produce characteristic changes or growth patterns used for identification: know how to make serial dilutions.

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