by jaxlee


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Genome
entire genetic complement
Genes
specific sequences of nucleotides that code for polypeptides or RNA molecules.
Structure of nucleic acids
1. polymer of nucleotides. 2. contains a pentose sugar- ribose or deoxyribose 3. contains a phosphate 4. C, G, U, T, A
Match the base pairs A, C, T, G, U q
AT CG AU
How many bonds for G and C?
Three
HOw many bonds for A and T
Two
Prokaryotes
Haploid and contain chromosomes and plasmids
positive selection
selecting a mutant by eliminating all the wt phenotypes.
Negative selection
results when an organism differs from the wild type in its requirements. (meaning that it is an auxotroph.
Ames Test. What does it test for?
The ames test is a way to test if a chemical is carcinogenic.
What are the steps for the ames test?
1. Take his- mutants with liver extract and the chemical or substance that is thought to be carcinogenic. 2. When the liver extract gets to work, the enzymes can turn chmeicals into mutagens. 3. Then spread the bacteria on a medium that does not have hisdine and if the bacteria starts to grow, it is reverent, meaning that the substance would be mutagenic.
Is a positive ames test completely reliable.
No, just because there is a positive ames test it doesn't mean that the chemical/substance is carcinogenic. YOu could then test with animals.
Genetic Recombination
the exchange of nucleotide sequences between two DNA molecules.
Recombiants
molecules that contain new arrangements of nucleotide sequences.
horizontal gene transfer
the passing of genes to the next generation, a donor cell gives part of it's genome to a recipient cell that could be a different species or even a different genus. The recipient will insert part of the donor into the it's own chromosome and then enzymes will degrade the rest. It then becomes recombiant.
Donor cell
gives away part of it's DNA
recipitent cell
inserts the donor cells parts of DNA into it's own chromosome
Transformation
the recipient cell can take up DNA from the environment like a dead organism.
What is the most popular experiment that deals with trasformation?
GRIFFITHS experiment with mice
Griffiths experiment: cells that are in a capsule...
Encapsulated cells can excape the body, they are deadly when you inject them into mice.
What are the encapsulated cells called?
They are called strain S because they make a smooth colonie on agar
What happens when you place Strain S with heat?
This causes the cell to become inactive and they do not kill the mice
What is the head strained capsulated cells called?
Strain R because they form rough colonies.
WHy is this experiment so important in genetics?
It is proof that DNA is the genetic material of cells and that trasmformation occurs
Competent:
they are cells that are able to take up DNA from thier environment, they become competent when there are alterations in the cell wall or the cytoplasmic membrane.
List all of the steps of Grittiths experiment
1. Inject live Strain S cells into mouse. The mouse dies. 2. Insert Strain S cells that are treated with heat and dead and now called Strain R cells into mouse. Mouse Lives. INsert live Strain R cells into the mouse, the mouse lives. Instert Strain R and Head treated Strain S celles into the mouse, the mouse dies and new bacteria is plated from that mouse showing that the strain R cells get the DNA for making thier own capsule from other strains. This can also occur in vitro.
What are the methods of horizontal gene transfer?
transformation, transduction and bacterial conjugation
Transduction
involves the trasfer of DNA from one cell to another by a replicating virus.
Can a cell transfer if it cannot be invaded by a virus?
No, both the donor and recipient need to be infected in order for it to transduce
bacteriophage
a virus that infects the bacteria
phage
means that it can eat it up! a virus that can infect bacteria.
What is the first step to transduction?
the bacteriophage must attach itself to a bacterial host cell and inject some of it's dna.
Then what happens?
The cells actual DNA gets degraded by the bacteriophages enzymes.
Then what?
The phage is now able to control how and what the cell does and tells the cell to make new phage DNA and Phage Proteins.
Transducing phages
fragements of DNa that was incorportaed into the baceterial dna
Now what happens?
The host cell will lyse with new daughter and transducing phages.
Then what?
The host cell becomes recombiant, because it now has the donated dna inside of it's chromosome.
Out of all three types of horizontal gene transfer, which donor cell stays alive?
The donor cell that is involved with conjugation.
Conjugation
It requires that the donor cell and the recipient cells actually touch.
Conjugation pili
The sex pili. it is an extention sticking out of the surface of the cell. (like a penis!! ha)
Where is the instructions of the conjugation pili located?
On the plasmid called the F fertility plasmid, also known as the F factor.(F+ cells if the contain the F plasmid) if they lack the sex pili they are F-.
What is the first step to conjugation?
The sex pilus has to connect to the donor cell (F+ to a F-) And the pilus brings them close together
NOw what?
After the cells touch, they the become stable and fuse together thier cell membranes.
Next
One strand of the F plasmid transfers it self to the recipient
Then
the F- recipient then makes a complementary strand of F plasmid dna which then makes itself an F+ cell.
Then
The donor cell makes a complementary plasmid Dna strand.
What are Hfr's?
They are high frequency of recomination cells. They can conjugate with F - cells after the F plasmid is inegrated
What is a palindrome?
It is a sequence that is read the same backwords as forwards
What is another name for a palindrome/
IT is also called an inverted repeat.
phenol coefficient
means that there is an coefficient great that 1.0 which means that the agent is greater or better then or more effective then phenol
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