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the synthesis of a complementary strand of RNA from a DNA template.
DNA is transcribed to make RNA (mRNA, tRNA and rRNA) |
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| The study of what genes are, how they carry information, how information is expressed and how genes are replicated |
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| A segment of DNA that encodes a functional product, usually a protein |
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| Structure containing DNA that physically carries hereditary information; the chromosomes contain the genes |
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| All the genetic information in a cell. |
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| carries the coded information for making specific proteins from DNA to ribosomes, where proteins are synthesized. |
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| involved in protein synthesis |
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| forms an integral part of ribosmomes, the cellular machinery for protein synthesis |
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| Replication/Transcription/Translation |
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Transcription Translation
DNA----------------->mRNA------------------>protein
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| Replication
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DNA |
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mRNA is translated in codons (3 nucleotides) resulting in a protein with a specific amino acid sequence.
Translation of mRNA begins at the start codon: AUG
Translation ends at nonsense codons: UAA, UAG, UGA |
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61 sense codons on mRNA encode the 20 amino acids
tRNA carries the complimentary anticodon |
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| A permanent inheritable change in the genetic material; mutations may be neutral, beneficial or harmful |
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| Agent that causes mutations. (chemicals, radiation, xrays, etc) |
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| Occur in the absence of a mutagen; base substitutions and frameshift mutations may occur spontaneously. |
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| Base substition/Missense mutation |
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| Base substitution involves a single base at one point in the DNA sequence being replaced with a different base. As a result the wrong protein will be synthesized and the change will be known as a missense mutation. Sickle cell disease is an example of this type of mutation. |
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Uses bacteria to test for carcinogenic activity of an agent. The test exposes the bacteria to the agent and looks for the rate of mutation compared to the rate of spontaneous mutation in a control.
Studies show a 90% correlation rate between mutation in the Ames test and cancer studies in animals. |
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| Occurs during reproduction, between generations of cells |
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| Transfer of genes between cells of the same generation: transformation, transduction and conjugation |
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| Transfer of DNA from a donor bacterial cell which has lysed to a recipient "competent" cell through the environment. A competent cell is one whose membrane will allow transport of DNA fragments into a cell. |
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| In gram neg bacteria DNA from F+ donor cells to F- recipient cells is transferred by means of specialized pili which bring the 2 cells into direct contact. The DNA transferred is usually a plasmid bearing the F factor gene. The recipient F- cell becomes an F+ cell capable of initiating conjugation. In some strains designated Hfr (high frequency) the plasmid is attached to the cell's chromosome and during conjugation some or all of a copy of the donor cell's genome is transferred. The plasmids transferred during conjugation often carry genes for drug resistence. In gram pos bacteria sticky surface molecules create the direct contact between cells. |
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| Transfer of DNA from a donor bacterial cell to a recipient bacterial cell by way of a viral infection. A bacteriophage during the assembly stage in the donor cell acquires some bacterial DNA either instead of or in addition to the viral nucleic acid. When a new bacterial cell (the recipient) is infected by the phage it will gain new bacterial DNA for recombination. |
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| Small extrachomosomal pieces of circular DNA- found only in bacteria and some yeasts. Carries genes for sex pili and transfer of the plasmid. Encode enzymes for catabolism of unusual compounds; encode antibiotic resistence; may also carry genes for toxins. |
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| Gram negative rod-shaped bacteria, or cocobacilli. Transmitted to humans by bites of insects and ticks. Enter their host cell by inducing phagocytosis. Enter the cytoplasm of the cell and reproduce by binary fission. Responsible for typhus, murine typhus, Rocky Mountain spotted fever. |
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has unique developmental cycle that is perhaps their most distinguishing characteristic; gram neg coccoid bacteria; elementary body is the infective agent; transmitted to humans by interpersonal contact or by airborne respiratory routes.
Chlamydia trachomatis is best known- can cause blindness; most common sexually transmitted disease in US |
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Highly pleomorphic because they lack a cell wall; can produce filaments that resemble fungi (hence the name)
Most significant human pathogen is Mycoplasma pneumoniae, which is the cause of a common form of mild pneumonia. |
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