antibacteria lab

8/10/2019 AntiBacteria Lab

1/4

Katy Wong, Claudia Yuan, Monica Vitting

Mrs. Fern

Period 2

16 February 2012

Lab: Bacteria and Antibiotics

1. Archaebacteria are single celled prokaryotes that can survive extreme conditions and

Eubacteria are complex structures found in neutral conditions.

2. Eubacteria belongs to The Bacteria domain and Archaebacteria belongs to The Archaea

domain.

3. Monera- single-celled, may or may not move, have a cell wall, have no chloroplasts or other

organelles, and have no nucleus. Monera are usually very tiny with no visible feeding

mechanism. They absorb nutrients through the cell wall or produce their own by

photosynthesis.

4. Organisms are placed into kingdoms based on similarities or common characteristics. Some

of the characteristics that are used to determine placement are cell type, metabolism, and

reproduction. Bacteria are also classified by how they appear under the microscopeespecially with gram stain. Example) bacillus (rod), vibrio (s or comma).

5. Functions:

a. Flagellum-a swimming like movement

b. Cell Wall- structural support and protection and to maintain shape

c. Ribosomes- used for protein synthesis

d. Plasmid- Extrachromosomal genetic material

e. Capsule- enhances the ability of bacteria to cause disease

f. Nucleoid- location which contains the genetic material

g. Mesosome- help with cellular respiration and the breakdown of food for energy

h. Pili- used to protect the cells surface and to help the bacteria attach to other

surfaces6. a. Nutrition: Most bacteria are heterotrophic and may be saprophytic, obtaining nutrition

from dead, decaying matter. Bacteria can also be parasitic, obtaining nutrition from other

living organisms called hosts. Some bacteria are additionally autotrophic and make their

own food by a process called chemosynthesis.

b. Respiration: Most bacteria require oxygen for respiration for the breaking down of food

to release energy. Such bacteria are called aerobic bacteria. Some bacteria do not require

oxygen for respiration known as anaerobic bacteria.

c. Reproduction: Bacteria is reproduced by binary fission. Under favorable conditions, a

bacterium divides into two daughter cells. The nuclear material splits and one of which ispassed on to each daughter cell. The daughter cells grow, divide and reproduce; bacteria

reproduces at a fast rate. Escherichia coli divides every twenty minutes. A warm and humid

environment is ideal for the growth of bacteria. During unfavorable conditions like extremes

of temperature or dryness, the bacteria grow a cyst around themselves.

7. Antibiotics are also known as antibacterials. Theyare selective poisons that has been chosen

to kill the desired bacteria, but not the cells in human body. Most of the bacterial world falls into


2/4

one of two categories, Gram+ and Gram-, based on differences in the cell wall structure of bacterial

cells. For example, penicillin works only againstGram-positive bacteria by interfering with the

structure of a strong cell wall molecule called peptidoglycan. When the structural integrity of the

bacterial cell wall is compromised, the cell loses its protection and ultimately dies.

8. Human bodies fight bacterial infection by white blood cells. There are many different white

blood cells such as phagocyte, which it engulf Micro-Organisms. Also, lymphocytes, which itproduce antibodies that weaken a bacteria or pathogen by attaching onto it and it produces

antitoxins against the bacterium.

9. Genetic engineering is a set of technologies that are being used to change the genetic

makeup of cells and move genes across species boundaries to produce novel organisms.

Several bacteria play a major role in modern genetic-engineering techniques: by inserting

specific genes into the bacterial cell, the bacteria can be induced to produce the protein

which these genes encode. These proteins can then be used to produce medicines and

other vital substances, such as hormones.

Materials-

gloves

apron

petri dish

scientific q tip

Micrococcus luteus

Escherichia coli

saline solution

streptomycin

tertracycline erthyromycin

scientific tweezers

safety goggles

hole punched paper circles (heated for 10 seconds in the microwave)

wax tape

Procedure:

First we took the petri dishes and labeled the top with our names and the type of bacteria we used,

which was E. coli. We dipped our q tips in the bacteria and spread the bacteria over the petri dish.In the first square, we put a plain hole punch in the first quadrant Next we took the hole punch with

the streptomycin on it and put it in the middle of the second quadrant. Next, we took the

tetracycline hole punch and put that in the center of the third quadrant. We then took the

erythromycin hole punch and put it in the middle of the fourth quadrant. Finally, we closed the lid

of the petri dish and secured the outside with wax tape.
http://tami-port.suite101.com/gram-positive-gram-bacteria-a50738http://tami-port.suite101.com/bacterial-cell-wall-a32297http://tami-port.suite101.com/bacterial-cell-wall-a32297http://tami-port.suite101.com/gram-positive-gram-bacteria-a50738


3/4

Interpretation questions:

1. What does the zone of inhibition represent?

The zone of inhibition represents how effective the antibiotic is and how it inhibits the

growth of the bacteria.

2. How can the effectiveness of an antibiotic be measured?The effectiveness of an antibiotic can be measured by the size of the zone of inhibition. The

bigger the zone, the more effective the antibiotic is.

3. What is the best to controlling the growth rate of bacteria?...least?

I took the average data from the class and found that erythromycin is the best antibiotic at

controlling the growth rate of bacteria and streptomycin is the least bacteria- killing out of

the three antibiotics.

4. Did the antibiotic work the same for the bacteria types? How do you explain this?

Streptomycin worked almost equally for both of the bacteria types. Tetracycline and

erythromycin had more differences between the two bacteria. I looked at the class averages

and saw the similarities and differences between the effectiveness of the antibiotic and the

bacteria that was used.5. Which antibiotic seems to be the most effective?

Erythromycin seems to be the most effective. I took the class data and found the averages

for each of the antibiotics for the zone of inhibition. The mean for erythromycin was

30.7mm. The mean for tetracyline was 28.7mm. The mean for streptomycin was 25mm.

6. What is the difference between antiseptic and antibiotic?

Antiseptic- a substance that kills all living things

Antibiotic- a substance that kills only bacteria

7. What is the role of antibacterial agents, disinfectants, and antibiotics in controlling

bacteria?

The role of antibacterial agents, disinfectants, and antibiotics is to get rid of the bacteria so

that it does not spread. Some bacteria are extremely dangerous and it is important to getrid of them. Antibiotics can get rid of bacteria without harming anything else. Therefore,

you can give antibiotics to living organisms. Disinfectants are the same thing as antiseptics,

they kill everything they come in contact with.

8. Explain the overuse of antibacterial agents, disinfectants, and antibiotics and its effect

on bacteria? Effect on human illness?

Antibiotics can cause immunity to bacteria if overused. Disinfectants if used too much can

pollution to the environment. Disinfectants are harmful to human beings and all other living

things. Antibiotics if overused can cause a mutant strain of bacteria to evolve that can not

be treated with any antibiotics. That is very dangerous.


4/4

Works Cited

http://www.ruf.rice.edu/~bioslabs/studies/invertebrates/kingdoms.html

http://textbookofbacteriology.net/structure.html

http://www.publishyourarticles.org/knowledge-hub/biology/bacteria-its-occurrence-shape-

nutrition-physiology-useful-and-harmful-bacterias.html http://health.howstuffworks.com/medicine/medication/question88.htm
http://www.ruf.rice.edu/~bioslabs/studies/invertebrates/kingdoms.htmlhttp://www.ruf.rice.edu/~bioslabs/studies/invertebrates/kingdoms.htmlhttp://textbookofbacteriology.net/structure.htmlhttp://textbookofbacteriology.net/structure.htmlhttp://www.publishyourarticles.org/knowledge-hub/biology/bacteria-its-occurrence-shape-nutrition-physiology-useful-and-harmful-bacterias.htmlhttp://www.publishyourarticles.org/knowledge-hub/biology/bacteria-its-occurrence-shape-nutrition-physiology-useful-and-harmful-bacterias.htmlhttp://www.publishyourarticles.org/knowledge-hub/biology/bacteria-its-occurrence-shape-nutrition-physiology-useful-and-harmful-bacterias.htmlhttp://health.howstuffworks.com/medicine/medication/question88.htmhttp://health.howstuffworks.com/medicine/medication/question88.htmhttp://health.howstuffworks.com/medicine/medication/question88.htmhttp://www.publishyourarticles.org/knowledge-hub/biology/bacteria-its-occurrence-shape-nutrition-physiology-useful-and-harmful-bacterias.htmlhttp://www.publishyourarticles.org/knowledge-hub/biology/bacteria-its-occurrence-shape-nutrition-physiology-useful-and-harmful-bacterias.htmlhttp://textbookofbacteriology.net/structure.htmlhttp://www.ruf.rice.edu/~bioslabs/studies/invertebrates/kingdoms.html

antibacteria lab

Documents