Genetics

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Genotype`

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is its genetic makeup, information tht codes for all the particular characteristics of the organism.

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phenotype

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is actual, expressed properties, eg: orgnisms abilityh to perform a particular chemical reaction. Phenotype is the manifestation of genotype.

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Haploidy

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A eukaryotic cell or orgnism with one of each type of chromosome.

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Diploidy

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Cell having two sets of chromosomes, diploid is the normal state of a eukaryotic cell.

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Mutations
Spontaneous,

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A mutation is a change in the base sequence of DNA.That change causes a change in the product coded for by the mutated gene.
pontaneous mutations occur without the presence of a mutagen
Mutagens are agents in the enviornment that cause permanent changes in DNA

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Selection of mutants

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Mutants can be detected by selecting or testing for an altered phenotype.
Postive selection involves the selection of mutant cells and the rejection of nunmutated cells.
Replica plating is used for negative slection-to detect, for example auxotrophs that have nutritional requirements not possessed by the parent (nonmutated) cell.

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Types of mutations

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1. A base substitution occurs when one base pair in DNA is replaced with a different base pair.
2. Alaternations in DNA can result in missense, mutations(which cause amino acid substitutions) or nonsense mutations(which create stop codons).
3. In a frameshift mutation, one or a few base pairs are deleted or added to DNA.
4. Mutagens are agents in the environment that cuase permanent changes in DNA.
5. Spontaneous mutations occur without the presence of a mutagen.

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Genetic recombination

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The rearrangment of genes from separate groups of genes, usually involves DN>A frfom different organisms; it constributes to gentic diversity.
In crossing over, genes from two chromosomes are recombined into one chromosome containing some genes from each original chromosome.
Mechanisms for genetic transfer in bacteria involve a portion of the cell's DNA being transferred from donor to recipient.
When some of the donors DNA has been integrated into the recipients DNA, the resultant cell is called a recombinant.

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Transformation in Bacteria

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during this process genes are transferred from one bacteruim to another as "naked" DNA in solultion
This process was first demonstratede in Streptococcus pneumoniae, and occurs naturally among a few genera of bacteria.

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Transduction in Bacteria

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DNA is passed from one bacterium to another in a bacteriphage and is then incorporated into the recipients DNA.
In generalized transduction, any bacterial genes can be transferred.

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Conjugation in Bacteria

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Process requires contact between living cells.
One type of genetic donor cell is an F1; recipient cells are F2. F cells contain plasmids called F factors; these are transferred to the F2 cells during conjugation.
When plasmid becomes incorporated into the chromosome, the cell is called an Hfr (high frequency of recombination) cell.
During conjugation, an Hfr cell can transfer chromosomal DNA to an F2 cell. Usually, the Hfr chromsome breaks before it is fully transferred.

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Gene Manipulation
Plasmids

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Plasmids are self-replicating circular molecules of DNA carrying genes that are not usually essential for the cell's survival.