Warm ­ Up
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Warm ­ Up
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AP Biology
1. Warm ­ Up 5 2. Week Assignments Due
3. pGLO Lab Part 1
4. Chapter 18 Notes
Announcement
Due Today: Week 4 Spring Assignments Due Monday, March 4: Work on pGLO Lab and begin preparing for test
No Quiz Monday/TEST FRIDAY
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pGLO Lab
Lesson 1 Focus Questions
There are many considerations that need to be thought through in the process of
planning a scientific laboratory investigation. Below are a few for you to ponder as you take
on the challenge of doing a genetic transformation.
Since scientific laboratory investigations are designed to get information about a
question, our first step might be to formulate a question for this investigation.
Consideration 1: Can I Genetically Transform an Organism? Which Organism?
1. To genetically transform an entire organism, you must insert the new gene into every
cell in the organism. Which organism is better suited for total genetic transformation—
one composed of many cells, or one composed of a single cell?
2. Scientists often want to know if the genetically transformed organism can pass its new
traits on to its offspring and future generations. To get this information, which would be a
better candidate for your investigation, an organism in which each new generation
develops and reproduces quickly, or one which does this more slowly?
3. Safety is another important consideration in choosing an experimental organism. What
traits or characteristics should the organism have (or not have) to be sure it will not
harm you or the environment?
4. Based on the above considerations, which would be the best choice for a genetic
transformation: a bacterium, earthworm, fish, or mouse? Describe your reasoning.
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pGLO Lab
Consideration 2: How Can I Tell if Cells Have Been Genetically Transformed?
Recall that the goal of genetic transformation is to change an organism’s traits, also known as their phenotype. Before any change in the phenotype of an organism can be detected, a thorough examination of its natural (pre­
transformation) phenotype must be made. Look at the colonies of E. coli on your starter plates. List all observable traits or characteristics that can be described:
The following pre­transformation observations of E. coli might provide baseline data to make reference to when attempting to determine if any genetic transformation has occurred.
a) Number of colonies
b) Size of : 1) the largest colony
2) the smallest colony
3) the majority of colonies
c) Color of the colonies
d) Distribution of the colonies on the plate
e) Visible appearance when viewed with ultraviolet (UV) light
f) The ability of the cells to live and reproduce in the presence of an antibiotic such as ampicillin
1. Describe how you could use two LB/agar plates, some E. coli and some ampicillin to determine how E. coli cells are affected by ampicillin.
2. What would you expect your experimental results to indicate about the effect of ampicillin on the E. coli cells?
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pGLO Lab
Consideration 3: The Genes
Genetic transformation involves the insertion of some new DNA into the E. coli cells. In addition to one large chromosome, bacteria often contain one or more small circular pieces of DNA called plasmids. Plasmid DNA usually contains genes for more than one trait. Scientists use a process called genetic engineering to insert genes coding for new traits into a plasmid. In this case, the pGLO plasmid has been genetically engineered to carry the GFP gene which codes for the green fluorescent protein, GFP, and a gene (bla) that codes for a protein that gives the bacteria resistance to an antibiotic. The genetically engineered plasmid can then be used to genetically transform bacteria to give them this new trait.
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pGLO Lab
Consideration 4: The Act of Transformation
This transformation procedure involves three main steps. These steps are intended to
introduce the plasmid DNA into the E. coli cells and provide an environment for the cells to
express their newly acquired genes.
To move the pGLO plasmid DNA through the cell membrane you will:
1. Use a transformation solution containing 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:
3. Provide them with nutrients and a short incubation period to begin expressing their
newly acquired genes.
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pGLO Lab Activities pages 37 ­ 46
A. Review Procedure
B. Discuss Procedure
C. Optimize one part of the procedure 8
Chapter 18 Notes 9
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I. Viruses
A. Discovery‐ _________________ in 1883, the Tobacco Mosaic Disease was caused by a virus found to have characteriscs that differed from all other living creatures.
B. Parts (Figure 18.2)
1. Double‐stranded DNA or RNA or Single‐stranded DNA or RNA
2. Protein shell (____________) enclosing genome
*May have ________________ around capsid
Example of a Virus: _______________
C. Replicaon‐ Viruses can only reproduce within a _________ cell (Figure 18.3). Genome of a virus make its way into a cell
D. Viral genome reprograms cell to copy ___________ genes and manufacture capsid proteins (Host cell provides ________________ and tools)
E. Viral parts are put together spontaneously (____________‐ assembly)
F. Bacterial Viruses (Phages) (Figure 18.4 and 18.5)
1. __________ cycleà Death of host cell (Virulent viruses)
2. _____________ cycleà Viral DNA is copied without destroying the host (Temperate viruses)
*DNA from virus integrates into bacterial chromosome = _____________
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Chapter 18 Notes
II. Bacteria A.
Reproduce quickly à Lots of ________________
B.
Genome arranged in a dense ball (Made of 1 circular double‐stranded _____________)
*Many bacteria have ________________ (lile separate DNA self‐replicang circles)
C.
Genec Recombinaon and Gene Transfer
1. ________________ – the alteraon of a bacterial cell’s genotype by the uptake of foreign DNA from the surrounding environment
2.
Transducon – ______________ transfer bacterial genes from 1 host to another (Figure 18.13)
i. Generalized– packaged viral DNA is transferred along with an ___________________ piece of host DN enters the Virus…OOPS!
ii. Specialized – Takes bacterial DNA near the ___________________ into next host cell…Also, an OOPS!
3.
__________________ – “Bacterial Sex” i.
Direct transfer of genes between 2 cells temporarily joined ii.
(Involves sex pili‐ _____ male transfers F plasmid to ________ female)
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Plasmid
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III. Plasmids
A. Definion‐ a small, circular DNA molecule separate from the i.
main bacterial chromosome that _____________ independently and can ii. reversibly incorporate into the chromosome creang an ______________
B. They are generally beneficial, but R plasmids are resistant to anbiocs
i.
The F plasmid has genes that produce sex ________________
C. Transposons (or Transposable Genec Elements or “ ____________ Genes”)
D. Definion‐ pieces of DNA that can move from one locaon to another in a cell’s genome
E. Some “_________ and paste” (conservave) and some “ ________ and paste” (replicave)
i. Simplest ones are called inseron sequences which consist of only DNA for the act of transposion itself…Code for enzyme _____________
ii. 4. Composite transposons include genes that “go along for the ride” 1. eg) Genes for anbioc resistance
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trp Operon 23
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IV. Control of Gene Expression
A. Two levels:
1. Cells can vary the ____________ of specific enzymes
2. Cells can vary the ____________ of enzymes already present. Trp Operon (Figure 18.20) *A Repressible Operon
a. The on/off switch for a series of related structural genes is called an ___________________
b. Operon is __________________ by a repressor which binds to the c. operator blocking aachment of RNA Polymerase to the __________________
3. The _________________ is a product of a regulatory gene can be acve or inacve
4. Tryptophan is a corepressor that binds to the repressor making it ______________________________
a. *Tryptophan presentà Acve repressor à Operon ______
b. Lac Operon (Figure 18.21) *An Inducible Operon
*Lactose presentà Inacve repressor à Operon _____
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Exit Questions: What genetic information do viruses contain?
Reminders
Due Monday, March 4: Work on pGLO Lab and begin preparing for test
No Quiz Monday/TEST FRIDAY
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