Molecular Biology Flashcards

Which is a palindrome?

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T/F. An enzyme that cuts or digests a palindromic DNA is called a DNA ligase.

Small circular DNA molecules found in bacteria which are not a part of the bacterial genome are called:

The enzymes that recognize specific DNA sequences and cut the sequence at specific locations are called:

Both restriction enzymes and bacterial plasmids are found in nature and in the lab they are used as tools in ______ ______ technology.

____ ____ are regions of un-pared bases at restriction sites.

T/F. Genetic differences between organisms, even organisms that are members of the same species, are due in part to differences in the proteins between the organisms.

DNA fragments produced by restriction enzyme action can be separated from one another by:

T/F. The separation of the DNA fragments is based on the positively charged molecules of DNA being attracted to the negative electrode of the chamber.

T/F The migration rate of DNA fragments increases the closer they get to the end of the gel.

The charge of a DNA molecule is due to the presence of…

You are setting up an agarose gel and you accidentally plug in the electrodes backwards. What is likely to happen when you turn on the current?

____ _____ cut double stranded DNA molecules.

T/F In addition to the single, circular chromosome, bacteria often contain extra DNA in the form of plasmids.

Looking at a picture of your gel which sample of DNA had contained the smallest fragment/s:

What would happen if you were to increase the concentration of agarose within a gel?

Say you are trying to grow a particular strain of bacteria while at the same time trying to prevent other strains from growing. How would you do this?

Put a _____ for resistance to a specific antibiotic in the bacteria and that specific antibiotic in the growth media.

If you are plating bacteria on plates with an antibiotic in the agar, why must you still use sterile techniques (choose all that apply)?

Select one or more:

You don't want to contaminate your work area, especially with antibiotic-resistant bacteria.

You may have other bacteria on your hands, which are also resistant to that antibiotic.

The bacteria you are using may be pathogenic (cause illness).

It makes cleaning up after an experiment easier.

The antibiotic may not have an effect on other microorganisms, such as mold.

Using this gel, how many fragments are in sample 1?

How many EcoRI cut sites are in the plasmid from sample 1?

What is the size of the fragment/s in sample 1?

The sizes of DNA fragments are typically measured in…

T/F. It does not matter if the molecular marker DNA was cut with a different restriction enzyme than the DNA fragment being analyzed.

Cutting this plasmid with EcoRI will yield three fragments that will add up to 5186 bp.

What is the size of the second biggest fragment?

How do you determine the total size of the plasmid?

What is the size of the largest fragment?

Use the following plasmid map for further practice. The total size of this plasmid 6486 bp.

Determine the number and size of the restriction fragments generated by digestion with EcoRI.

T/F. Cutting a circular piece of DNA at one site will yield one fragment while cutting a linear piece of DNA at one site will yield two fragments.

T/F. A change in phenotype is always associated with a change in an organism's appearance.

Which of the following are possible changes in phenotype that can be the result of a change in genotype? (for full credit, choose all that apply)

Antibiotic resistance.

Loss of the ability to metabolize certain nutrients.

An increased rate of reproduction.

Changes in morphology.

The ability to cause disease in a particular host.

These show the difference in the appearance between the colonies (phenotypes) under UV light (the Petri dish on the left) and under white light (the Petri dish on the right).

The phenotype difference is dependent on:

Below is a different example of phenotypes that involve blue vs white colonies. To see these phenotypes a chemical known as X-gal incorporated into the agar growth medium. X-gal is a chromogenic (color generating) compound that has the following structure:

X-gal is a galactose sugar with a glycosidic linkage to a chromophor (colored) molecule. As long as the chromophor stays joined to the galactose, it remains colorless. In the presence of the enzyme beta-galactosidase the glycosidic link is hydrolyzed (broken by the addition of water).

The free chromophor is now blue. Below are two Petri dishes with X-gal in the agar growth medium.

The bacteria growing on the two plates are the same. The difference is in the plasmids the bacteria contain.

The blue colonies are the result of:

T/F. The process in which DNA is transferred to or taken up by another organism is called translation.

If you digest the plasmid below with the restriction enzyme EcoRI, how many fragment(s) will result?

The smallest DNA fragment that is not a part of the ladder is in lane:

In lane "D", what is the approximate size of the largest fragment?

In lane "A" assume that the DNA came from a plasmid. How many cuts must have been made by restriction enzymes to create the number of DNA fragments seen?

What is the origin of the DNA used for the standard ladder?

T/F. It is possible for two different strains of bacteria with two different plasmids to be resistant to the same antibiotic.