1.3 Transmission of mutations by vertical gene transfer
Vertical gene transfer is the transfer of genetic information, including any genetic mutations, from a parent to its offspring. As you briefly saw in Week 1, bacteria reproduce by binary fission, where the cell divides into two identical daughter cells. As in humans, the genetic information in bacteria is encoded in DNA, which is packed into chromosomes. During binary fission, the chromosomal DNA is copied, so that each new daughter cell inherits an exact copy of the parent cell’s chromosomes (Figure 3).
Activity 1 Exploring vertical transmission
Allow about 10 minutes
Begin by watching the following animation which illustrates the process of binary fission in E. coli. Then complete the activity below.
Apply what you have learned and the information about binary fission in the animation to complete the following sentences. Select the appropriate word from the list.
(a) The DNA in both of the daughter cells is [identical/similar/different] to the DNA in the parent cell.
Answer
During binary fission, the genetic material (DNA) is copied so that each new daughter cell inherits an exact copy of the parent cell's DNA.
(b) If an E. coli bacterium contains a genetic mutation in a chromosomal pbp gene, both of its daughters will [always/sometimes/never] contain a mutation in the pbp gene.
Answer
During binary fission, the genetic material (DNA) is copied, so that each new daughter cell inherits an exact copy of the parent cell’s DNA. When the parent DNA is copied during binary fission, any genetic mutations will also be copied, and consequently inherited, by both of the daughter cells.
(c) If the parent bacterial cell contains a genetic mutation that results in resistance to β-lactam antibiotics, both of the daughter cells will [always/sometimes/never] be resistant to β-lactam antibiotics.
Answer
During binary fission, the genetic material (DNA) is copied, so that each new daughter cell inherits an exact copy of the parent cell's DNA. When the parent DNA is copied during binary fission, any genetic mutations will also be copied, and consequently inherited, by both of the daughter cells. If these genetic mutations give rise to antibiotic resistance in the parent bacteria, they will also result in antibiotic resistance in both of the daughters.
Vertical gene transfer is only one of the ways in which bacteria can spread antibiotic resistance genes. In the next section you will look at another – horizontal transfer.
OpenLearn - Understanding antibiotic resistance
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