BIOL 142 Lecture Notes - Chromosome, Operon, Bacteriophage
Bacteria reproduce by the process of Binary Fission: the chromosome in the mother cell is
replicated and a copy is allocated to each of the daughter cells.
This results in genetically identical daughter cells.
However, genetic exchanges between bacteria prior to replication of the genome result in
genetic diversity that is passed on to daughter cells. There are 3 types of genetic exchanges
that Bio 142 will touch on: 1. Transformation, 2. Transduction, and 3. Conjugation
Gene Cloning
Gene cloning is the incorporation of a foreign gene into a vector to produce a
recombinant DNA molecule that replicates and expresses the foreign gene in a
recipient cell.
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Regulation of Gene Expression
Expression of genes is regulated by intracellular or environmental conditions.
•
An operon is a set of genes that is transcribed as a single unit and expressed
coordinately.
Specific regulation induces or represses a particular gene or operon.
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Examples include Lac Operon
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Bacterial Genome Organization
Chromosomal DNA
1.
Plasmids
2.
Chromosomal DNA
Bacterial chromosome is a circular molecule of DNA that functions as a self-
replicating genetic element (replicon)
•
The chromosome replicates semi conservatively; each DNA strand serves as a
template for synthesis of its complementary strand.
•
Replication of the chromosomal DNA in bacteria starts at a specific chromosomal site
called the origin and proceeds bi-directionally and the replicated chromosomes are
partitioned into each of the daughter cells.
•
Most bacteria have a haploid genome.
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Typically, double stranded circular DNA
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Spontaneous mutations in individual bacteria are rare
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Plasmids
Discrete, extrachromosomal genetic elements in bacteria.
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Plasmids replicated independently of the bacterial chromosome
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Bacterial Genetics
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Document Summary
Bacteria reproduce by the process of binary fission: the chromosome in the mother cell is replicated and a copy is allocated to each of the daughter cells. However, genetic exchanges between bacteria prior to replication of the genome result in genetic diversity that is passed on to daughter cells. There are 3 types of genetic exchanges that bio 142 will touch on: 1. Gene cloning is the incorporation of a foreign gene into a vector to produce a recombinant dna molecule that replicates and expresses the foreign gene in a recipient cell. Expression of genes is regulated by intracellular or environmental conditions. An operon is a set of genes that is transcribed as a single unit and expressed coordinately. Specific regulation induces or represses a particular gene or operon. Bacterial chromosome is a circular molecule of dna that functions as a self- replicating genetic element (replicon)
