Lab Chapters 9 Flashcards
A gene is
piece of DNA which provides the instructions for making (codes for) a protein
Genetic transformation involves
insertion of a gene into an organism in order to modify a particular trait or, perhaps, provide the organism with a wholly new trait
How can genetic transformation be used in bioremediation
bacteria can be genetically transformed with genes enabling them to digest oil spills
What is the source for GFP?
Jellyfish aequorea victoria
In this activity, you will be moving moving genes from one organism to another using
plasmid DNA (small circular pieces of DNA)
True or false: In addition to their circular genome, bacteria generally possess one or more plasmids
True
How do plasmids contribute to bacteria survival?
Plasmids contain genes for traits that may be beneficial to bacterial survival. In nature, bacteria can transfer plasmids back and forth allowing them to share these beneficial genes. This natural mechanism allows bacteria to adapt to new environments. The recent occurrence of bacterial resis-tance to antibiotics is due to the transmission of plasmids
The bio-rad PGLO plasmid encodes for two genes. What are they?
GFP and a gene resistant to ampicillin
The gene regulation system PGLO encodes for is unique because
pGLO also incorporates a special gene regulation system (an inducible promoter), which can be used to control expression of the fluorescent protein in transformed cells
The gene for GFP can be switched on in transformed cells by adding
The sugar arabinose
Selection for cells that have been transformed with pGLO DNA is accomplished by
Growth on antibiotic plates
The promoter that controls the expression of the ampicillin resistance gene is always active , unlike
The promoter controlling GFP expression
When viewed under ultraviolet light, transformed cells will appear ___ on plates not containing arabinose, and _____ when arabinose is included in the nutrient agar medium.
white (wild-type phenotype)
fluorescent green
To move the pGLO plasmid DNA through the cell membrane you will:
- Use a transformation solution of CaCl2
(calcium chloride). 2. Carry out a procedure referred to as heat shock.
For transformed cells to grow in the presence of ampicillin you must:
Provide them with nutrients and a short incubation period to begin expressing their newly acquired genes before you transfer them to a medium that contains ampicillin.
The act of transformation is intended to
introduce the plasmid DNA into the E. coli cells and provide an environment for the cells to express their newly acquired genes.
The heat shock water bath is set at ___C for ___seconds
42C
50sec
The stack of plates should be placed ____ before being placed in a 37C incubator overnight
Upside down
There are approxi-mately ? genes in the human genome.
25,000
TorF: in most cases, it is correct to say that each gene codes for a unique polypeptide: one gene, one polypeptide.
True
Organisms regulate expression of their genes and ultimately the amounts and kinds of proteins present within their cells for a myriad of reasons, including
developmental changes, cellular specialization, and adaptation to the environment
TorF:Gene regulation not only allows for adaptation to differing conditions, but also prevents wasteful overproduction of unneeded proteins which would put the organism at a competi-tive disadvantage
True
What is the purpose of a promoter?
Regulation of the expression of proteins often occurs at the level of transcription from DNA into RNA. This regulation takes place at a very specific location on the DNA template, called a promoter, where RNA polymerase sits down on the DNA and begins transcription of the gene.
What is the purpose of a promoter?
Regulation of the expression of proteins often occurs at the level of transcription from DNA into RNA. This regulation takes place at a very specific location on the DNA template, called a promoter, where RNA polymerase sits down on the DNA and begins transcription of the gene.
What are operons
In bacteria, groups of related genes are often clustered together and transcribed into RNA from one promoter. These clusters of genes controlled by a single promoter are called operons.
The three genes (araB, araA, and araD) that code for three digestive enzymes involved in the breakdown of arabinose are clustered together in what is known as the
Arabinose operon
Production of these three proteins (araB, araA, and araD) is dependent upon the initiation of transcrip-tion from a
single promoter, PBAD
.
Transcrip-tion of araB, araA, and araD requires
requires the simultaneous
presence of RNA polymerase, araC, a transcription factor that binds DNA and facilitates transcription, and arabinose
When arabinose is present in the environment, bacteria
take it up.
Once inside the bacteria, the arabinose interacts directly with the araC protein which is bound to the DNA at the beginning of the arabinose operon. The interaction causes araC to
change its shape which in turn promotes (actually helps) the binding of RNA polymerase and the three genes araB, A, and D, are transcribed.
In the absence of arabinose the araC
returns to its original inactive shape and transcription is shut off
TorF: the DNA code of the pGLO plasmid has been engineered to incorporate aspects of the arabinose operon
True
the presence of arabinose, araC protein promotes the binding of RNA polymerase and GFP is produced. Why?
Both the promoter (PBAD
) and the araC gene are present. However, the
genes which code for arabinose catabolism, araB, A, and D, have been replaced by the single gene which codes for GFP
the absence of arabinose, araC no longer facilitates the binding of RNA polymerase and the GFP gene is
not transcribed.
When GFP is not made, bacteria colonies will appear to have
a wild-type (natural) phenotype—of white colonies with no fluorescence
