Powerpoints Flashcards
3 types of research approaches
- exploratory
- correlational
- experimental
exploratory research
gives a sense of variables you should explore more
ex: interviewing people who grow plants in their dorm rooms
correlational research
can show correlation between variables
ex: survey people who grow plants in their room about specific factors
experimental research
can show that one variable causes another
ex: buy plants and conduct experiments on them
negative control
condition we know will produce a negative result
OR condition that will have no change
ex: all plants die
postive control
condition we know will produce a positive result
ex: all plants grow
what do positive and negative controls do?
- ensure that assay is working
2. establish a range of possible results
1 mL =
1000 µL
What must you ALWAYS do before plating microbes?
VORTEX
What must be in each lab notebook entry?
Title, date, names
Purpose
Methods
Data
Conclusions
What side of the plate do you label?
the ager side
What should you label a plate with?
Name
Lab day/time
Date
What is plated (species)
Experimental variables that differ between plate (dilution, treatment)
Dilution formula
C1V1=C2V2
Fold dilution formula
Fold = C1/C2 = V2/V1
Why use a serial dilution?
it is more accurate and saves resources
What is a spot on an ager plate?
a colony
thousands of yeast growing from 1 cell that you plated
How many yeast colonies do you ideally want on a plate?
30-300
Techniques for repairing UV damaged DNA
- photolyase repair
2. nucleotide exision repair
Photolayse repair
specific enzyme senses bulge in DNA and repairs it
Nucleotide excision repair
enzymes cut out the damaged region of DNA
Which technique of DNA repair did placental mammals loose?
photolayse repair
can only use nucleotide excision repair
Qualities to consider when selecting a model organism
- How well they model the organism we are studying
- Ethics
- Ease of growing in lab
- Cost
- Generation time
- Size
- Ease of genetic manipulation
Baker’s yeast scientific name
Saccharomyces cerevisiae
Why use baker’s yeast as a model organism?
easy to grow in lab
2 hours per cell division
30% yeast genes shared with humans
Properties of baker’s yeast
single-celled eukaryote
fungi
can be grown as haploid or diploid
used since egyptians to bake bread
rad1 yeast
lack nucleotide excision repair
What happens to humans without nucleotide excision repair?
suffer from xeroderma pigmentosum
need to take extreme precautions to avoid sunlight
Why store yeast agar plates face side down?
Keeps yeast in the dark
photolayse repair mechanism cannot work
4 research ethics
- honesty
- objectivity
- carefulness
- openness
Animal use ethics
use lowest organism and fewest animals as possible
practice proper care and respect for animals
get IACUC approval
Human subjects ethics
respect dignity, privacy, and autonomy
strive to distribute benefits and burdens fairly
informed consent
must have IRB approval
Standardizing data rough example
make positive control 100% survival
make percents based off of this
this is an example
systematic error
error in a particular direction
affects the average
random error
fluctuation in measurement in either direction
affects the spread around the mean
reduce by repeating trials
What should a scientific poster do?
summarize the main finding
What should a figure caption have?
descriptive title that summarizes the results of the figure
specific information on how the figure was made
should include what error bars represent and how many replicates were averaged for each point
Steps to using the microscope
- turn on power and lights
- set magnification to 10x
- adjust oculars
- focus on c. elegan
- adjust mirror and lense
- increase magnification
Information on c. elegans
eukaryotes
hermatphrodites
eat bacteria
hermatphodites
can self fertilize or mate with male
How many cells are total in each c. elegan?
1000
What percent of genes of c. elegans are homologous to human genes?
40%
What is the lifespan of c. elegans?
3 weeks
Positive control of choosy worm choice assay
food source (bacteria) on one side of the plate
all the worms should move towards this food source
Negative control of choosy worm choice assay
same food source (bacteria) on both sides of the plate
all the worms should move towards both ends of the plate
Positive control of choosy worm survival assay
provide known food source, like OP50
Negative control of choosy worm survival assay
provide known pathogen or no food
What do dead worms look like?
straight line
General steps of plating worms (video goes more in depth)
- wash c. elegans off plate with 1000µL of M9 buffer
- spin to remove dirty M9
- repeat and wash 2x with 1000µL each time
- add 1000µL fresh M9
- check and adjust concentration to around 40 worms/5µL
Why do we have to wash worms multiple times?
to remove excess waste and bacteria
Supernatant
the excess liquid above the worms
How to mix worms without killing them?
flick them
do not vortex worms
null hypothesis for a choosy worm choice assay
worms will have no preference (50% on each side)
Two numbers needed to perform stats tests
number of successes
number of trials (successes + failures)
p-value
probability of obtaining your (or more extreme) data if the null hypothesis is true
What test do you use to compare results between 2 experiments (groups?)
2x2 contingency table
Standard deviation
measures variation to mean
standard error
measures variation to true value/population mean
What values does systematic error effect?
average and standard deviation
Where should glass slides by disposed?
glass waste only
What goes in bio waste?
everything except for paper towels
Random error can be reduced by
replicates
Systematic error can be reduced by
normalization
The lights are not working in a bulb give hypothesis + prediction
Hypothesis: the batteries are dead
Predicition: if I replace the batteries, the light will work
