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Christina Comino MSMS Work Sample Class of 2018

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Christina Comino

on 13 February 2016

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Transcript of Christina Comino MSMS Work Sample Class of 2018

Question:
After bacteria has been deposited on a doorknob, will certain strains of bacteria become less common than others due to the amount of time that has passed since the bacteria have been put on the doorknob?
Hypothesis:
I believe that after a doorknob is infected with a variety of bacteria, over time there will be fewer strains of bacteria on the surface of the doorknob because some types of bacteria will die off because they are not suited to the environment of the doorknob.
Materials:

Petri dishes prepared with agar gel
Three doorknobs
Sterile cotton swabs
Disinfectant (diluted bleach)
Source of Bacteria (a really dirty rag)
Resealable bags
Black and white graph paper
Timer
Paper Towels
Sharpie Marker

Work Sample
Christina Comino
Class of 2018

Sacred Heart High School
(601)-818-3268

Procedures:
Put on proper safety gear
Disinfect doorknob with bleach dilution
Dry with paper towels
Rub doorknob on dirty rag to transfer bacteria to it
Place the doorknob into a resealable bag, seal it, and wait.
Wait 5 minutes
Unwrap sterile swabs and swab the surface of the doorknob when the set time has passed
Open a petri dish, swab the dish in a zigzag check pattern with the swab
Close the dish, place it in its own resealable bag, and label it


Notes on Procedures and Data:
The time to wait between infecting the doorknob and swabbing it varied. There were a total of 10 set times: a control taken immediately upon infecting, 5 minutes after, 10 minutes, 20 minutes, 40 minutes, 60 minutes, 90 minutes, 2 hours, 3 hours, and 4 hours.

For each of these times, three dishes were made to ensure that all data was consistent. A total of 30 petri dishes were used in the experiment.

Data was collected for 19 days, starting the day that bacteria was applied to the dishes.

In order to collect data and prove or disprove the hypothesis, it is assumed that a different color of bacteria indicates a different strain of bacteria.
Control Group
(Sample Taken Immediately):
Dish 1:
Dish 2:
Dish 3:
All three of the dishes contained a reddish bacteria, a pale yellow bacteria, and a whitish clear bacteria. Only Dish 1 and Dish 3 contained a darker blackish bacteria.
Group 1
Sample Taken After 5 Minutes
Dish 1:
Dish 2:
Dish 3:
All three of the dishes contained pale yellow, red, and whitish clear bacteria, but no other kinds.
Group 2
Sample Taken After 10 Minutes
Dish 1:
Dish 2:
Dish 3:
All of the dishes contain yellow bacteria. Dishes 2 and 3 contain the red and white bacteria as well. Something with Dish 1 must have gone wrong because it had very little bacteria, even at the end of the experiment, and contained the more uncommon black bacteria.
Group 3
Sample Taken After 20 Minutes
Dish 1:
Dish 2:
Dish 3:
In all three dishes, only red and pale yellow bacteria are visible, although the size and number of spots of bacteria are inconsistent compared to Dishes 2 and 3.
Group 4
Samples Taken After 40 Minutes
Dish 1:
Dish 2:
Dish 3:
All three of the dishes have only pale yellow and red bacteria. Dishes 1 and 2 have bacteria that is smudged into lines which is different from most of the other dishes
Group 5
Sample Taken After 1 Hour
Dish 1:
Dish 2:
Dish 3:
All three dishes in this group have pale yellow bacteria and more widely spaced spots of bacteria. Dishes 1 and 2 have red bacteria also.
Group 6
Sample Taken After 1.5 Hours
Dish 1:
Dish 2:
Dish 3:
All three dishes have mostly pale yellow bacteria and a very small amount of red bacteria except for Dish 3. Dish 3 has the same sort of smudgy bacteria as Dishes 1 and 2 from Group 4.
Group 7
Sample Taken After 2 Hours
Dish 1:
Dish 2:
Dish 3:
Dish 1 and Dish 2 have pale yellow bacteria only. Dish 3 has pale yellow and red bacteria.
Group 8
Sample Taken After 3 Hours
Dish 1:
Dish 2:
Dish 3:
All three dishes in Group 8 have only pale yellow and red bacteria.
Group 9
Sample Taken After 4 Hours
Dish 1:
Dish 2:
Dish 3:
All three of the dishes in Group 9 have pale yellow and red bacteria, but oddly Dish 3 also has a spot of black bacteria
Data Table
Conclusions
The variety of bacteria did decrease as the wait times increased. The clear bacteria disappeared entirely and the black bacteria became less common, while the red and pale yellow bacteria remained most common. This gradual decrease in variety proves the hypothesis true.
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