Microbiology Exam 2

Select the appropriate uses of hydrogen peroxide for antimicrobial purposes.

- Mouthwashes - Low temperature sterilizing cabinets for colonoscopes - Wound cleansing

What is the reverse complement of the following DNA sequence: ATG CGA CCC CTG AAA TAT

ATA TTT CAG GGG TCG CAT

Replication

DNA Gyrase [bacteria/plant topoisomerase] DNA Topoisomerase I DNA Helicase RNA Primase DNA Polymerase I [repair] and III [replicase] DNA Ligase

Which enzyme corrects UV-light damage such as thymine dimers?

DNA Photolyase

Can you identify the cause of disease?

Helicobacter pylori - stomach ulcers/inflammation Pseudomonas aeruginosa - sepsis Leishmania major - Leishmaniasis Mycobacterium tuberculosis - Tuberculosis Plasmodium falciparum - Malar

How do you know how long each DNA fragment is when analyzing a completed gel?

How its distance compares to distance traveled by standard fragments of a DNA ladder

Describe one way that regulatory RNA's regulate transcription and protein synthesis.

Regulatory RNA's bind complementary to mRNA and either cleave and degrade the mRNA or they prevent the ribosome from "reading" or "transcribing" it.

Select the statement that describes the antimicrobial activity of chlorhexidine.

Targets cell membrane components and denatures proteins

In gene therapy, why might miRNA or siRNA, within an adenovirus, be injected into a patient?

To silence or repress a faulty gene.

Which strand is the coding strand?

Top

Select the most disadvantageous characteristic of phenolics.

Toxicity

Cytoplasmic enzymes are most likely to be disrupted by ______.

high temperatures

DNA Sequence Website

http://arep.med.harvard.edu/labgc/adnan/projects/Utilities/revcomp.html

DNA is semiconservative because the ______ strand will become half of the ______ molecule.

template; finished

Generate the reverse complement:

5' CGT CCG GCC AAT TAA 3'

Translation

Aminoacyl-tRNA synthetase - puts the Amino Acid on the tRNA

Which strand is the template strand?

Bottom

Generate the amino acid chain from the template strand:

MET ASP GLU THR STOP

DNA repair mechanisms can help alleviate the effects of _______.

UV radiation

Plasmids

are often the site of pathogenic genes

Select the advantages of phenolic compounds as antimicrobial agents.

- Remain effective in the presence of organic matter - Strongly microbicidal

Evaluate the statements below, and select those that correctly apply to the use of radiation as a microbial control mechanism.

- The use of radiation to control microbial growth comes in two forms; ionizing and nonionizing radiation. Of the two, ionizing radiation is the most destructive. - Nonionizing radiation, e.g., UV light, causes electrons to make a quantum leap to an orbital with a higher energy state, which causes thymine dimers to form, but does not create ions. - Ionizing radiation involves electrons being bombarded with enough energy to eject them from their atoms. X rays are an example of this.

How does transfer RNA differ from primer RNA?

- Transfer RNA brings Amino Acids to the growing polypeptide chain, whereas primer RNA does not. - Transfer RNA has anticodons that bind complementary to the mRNA, whereas primer RNA does not, it

5' TCG GCA ATT TTA 3' : Original

3' AGC CGT TAA AAT 5' : Complement 5' TAA TAT TGC CGA 3' : Reverse Complement

Catabolism

Cellular Metabolism

Match the processes to their proper description to test your understanding of horizontal genetic transfer mechanisms used in bacteria.

Conjugation - DNA transfer from a donor bacterium to a recipient via sex pili Transduction - DNA transfer from one bacterial cell to another cell via bacteriophage Transformation - The transfer of naked DNA from one cell to another

Transcription

DNA Gyrase DNA Topoisomerase I DNA Helicase RNA Primase RNA Polymerase I (DNA to rRNA) RNA Polymerase II (mRNA and small RNA) RNA Polymerase III (tRNA and small rRNA)

Which enzyme corrects base-pair mismatches during DNA replication?

DNA Polymerase I

How does DNA polymerase I differ from DNA polymerase III?

DNA Polymerase I only repairs DNA Polymerase III only adds base pairs

When you put the gel tray into the chamber, the wells must be oriented towards the black (negative) side of the chamber. What does this tell you about the characteristics of DNA molecules?

DNA is negatively charged

A Eukaryotic cell is treated with an Aminoacyl-tRNA-synthetase inhibitor. How would this affect DNA replication

DNA replication would not be affect, Amino-acyl-tRNA-synthetase is only used in RNA Translation

A technician is afraid of the presence of endospores on their probe that will enter a patient's body, would they decontaminate it, why or why not?

Decontamination only reduces quantities of organisms or toxins to safe/tolerable levels, it would not be appropriate for removing endospores or for probes that enter patient's bodies.

Physical and Chemical Control of Microbes

Drag and drop the labels into the correct empty boxes to complete the concept map.

Why are bacterial endospores resistant to physical and chemical control mechanisms?

Endospores are composed of many layers of protein, so they are strong, rigid, tough, indestructible, impervious to many dangers, etc.

Gel electrophoresis can only be used for the separation of DNA.

False

What is the name of the specific segment of the DNA with the code for the production of a protein?

Gene (or Exon)

anabolism and catabolism

Glucose

Inhibitors of DNA replication, transcription, and translation have been used in the clinic to treat viral infections, autoimmune disorders (diseases where the body's own host defense response cells attack itself), and cancer. In thinking of DNA Polymerase 1 inhibitors, describe what effect using this inhibitor would have on a replicating cell that experience UV light damage.

Inhibiting DNA polymerase 1, the polymerase that repairs DNA damage, would mean damage is not repaired and that damage would potentially exist in the daughter cell.

What is the role of temperature in PCR?

It is used to separate and anneal the nucleic acids

Actions on Proteins

Label the image to review how various antimicrobial agents alter protein structure and function.

Catabolism

Respiration

What best explains how PCR can be used to detect an infection?

Specific primers are used that would result in the amplification of DNA from an infectious agent if it was present in the patient. That amplification can be seen with the presence of a specific size fragment when the PCR product is ran on a gel.

Which of the following is not a mechanism of horizontal gene transfer?

Spontaneous mutations

What is the process that destroys or removes all microorganisms and microbial forms, including, bacterial endospores on inanimate objects? (sterilization, disinfection, degermination, or anti-sepsis)

Sterilization (Autoclave, boiling things with steam)

If you were trying to come up with an easy-to-remember analogy for the polymerase chain reaction, you would likely say PCR is similar to a _____.

photocopier

Sanitization is a process by which _____.

the microbial load on an object is reduced

Where does transcription take place in a Eukaryotic cell?

Nucleus (or nucleoplasm)

Resistance to Control Agents

Label the image to review the relative resistance of various microbes to microbial control agents.

What differences, if any, exist between gene locus and gene allele

Locus = location = gene location on chromosome. Gene allele = variations of the gene at the locus on the chromosome

Why are mRNAs capped and tailed? ONLY ONE OF THE THREE ANSWERS ARE NECESSARY

Protect against degradation Provide signal for exporting from the nucleus Provide signal for starting and stopping transcription

A bacteria is treated with a DNA Gyrase inhibitor; how would this affect translation

The inhibitor would stop any enzyme effects so the enzyme would no longer be able to bind to a substrate.

Gene Cloning

The same basic recombinant DNA technology process used to synthesize Factor VIII for hemophilia treatment was first used to synthesize large amounts of insulin in the laboratory in the 1970s. Conducting additional research as necessary, complete and order the following statements to demonstrate your understanding of this process.

What determines the distance that fragments move through the gel?

The size of the fragment

Of the following, which best describes the role of Zones of Adhesion in recombinant DNA technology?

Zones of adhesion are like chutes on the cellular surface that facilitate the entry of DNA into the cell. When the cell is doused in a salty ion solution, these pores widen and when the cells are shocked by heat, freely floated naked DNA readily enters the cell and is eventually integrated into the chromosome or plasmid.

Generate the amino acid chain from the template strand:

MET THR SER PRO STOP

Heat Control

Move the correct terms into the empty boxes to complete the concept map describing heat as a mechanism of microbial control.

Types of Horizontal Gene Transfer

Move the descriptions to the correct type of bacterial genetic recombination.

The -omics

Move the terms into the correct empty boxes to complete the concept map that describes emerging fields in biotechnology.

Physical Control of Microorganisms

Move the terms into the correct empty boxes to complete the concept map.

What is used to cut DNA into fragments for separation and analysis?

Restriction enzymes

Non-Template Strand 5' GTC ACC CAT GGA GG 3' 3' CAG TGG GTA CCT CC 5'

Template Strand 5' GUC AGC CAU GGA GG 3'

Inducible vs. Repressible Operons

Move the terms into the correct empty boxes to complete this concept map contrasting inducible and repressible operons.

Has the same sequence as the mRNA (antisense is used as the template)

Non-Template Strand Coding Strand Sense Strand Positive Strand

What are the three components of a nucleotide?

Phosphate - Sugar (deoxyribose or the ribose), - Nucleic Acid - Purines/Pyrimidines, Adenine, Thymine(only in DNA) Guanine Cytosine, Uracil (only in RNA)

Methods of Microbial Control

Please label the image, including the definitions at the bottom, to review various methods of microbial control.

Comparing Genetic Technologies

Please label the images to demonstrate your understanding of the various technologies that may be involved in genetic engineering.

Lac Operon

Please label this figure to demonstrate your understanding of the lac operon as a model of inducible gene regulation in bacteria.

Types of Horizontal Gene Transfer

Please watch the video below, and then use what you have learned from the chapter to complete the table below by dragging the labels to their correct location, demonstrating your understanding of types of horizontal gene transfer.

Match the carbohydrate class with the appropriate example of a carbohydrate in that class.

Polysaccharide - Cellulose Disaccharide - Lactose Monosaccharide - Fructose

Used to make mRNA [RNA grows in 5' -> 3' Direction]

Template Strand Non-Coding Strand Anti-Sense Strand Negative Strand

What determines the piece of DNA that is amplified in PCR?

The specific primers used