11/15/2023 0 Comments Binary fission in bacteriaWhen an organism gets its energy from the sun, we call it a Phototroph Various species of bacteria do both these things. Plants and some of the Protista get their energy from the sun. We get our energy from the food we eat – in other words from organic matter. Plasmids can also move to new bacterial cells when a cell dies, the same as ordinary cell DNA can. This is called conjugation and it is as close to what we think of as ‘sex’ as bacteria get. Then the whole cell DNA is replicated into the other cell. Sometimes, this plasmid DNA can become joined up with – or incorporated into – the normal bacterial cell DNA. In doing so, they give the other cell the ability to generate sex pili – effectively making the second cell male as well. Once their cell walls are touching, these plasmids reproduce copies of themselves into the other cell. They cause the cell to grow special sex pili, which reach out from the cell and attach to other cells that they contact. Some plasmids give the bacterial cells that possess them a sort of masculinity. They often give the host cell extra abilities, such as resistance to antibiotics or the ability to make a useful enzymes. Plasmids are small circles of DNA and they can replicate themselves within a bacterial cell. Many bacteria can also contain smaller sections of DNA in the form of Plasmids. Viruses which attack bacterial cells can also be the agents of the transfer DNA from one cell to another.īacterial DNA is normally a single circular double strand. If the dead cell’s DNA codes for a property they do not have, then they have gained this property. Other nearby bacterial cells can absorb this DNA and add it to their own – and in this way they gain extra DNA. This includes the DNA, which may be complete or broken into bits. When one bacterial cell dies and its cell wall is ruptured, the contents are released into the environment. Some methods of DNA transfer between cells seem almost accidental. Bacteria are not quite the same as the higher animals, but they do transfer DNA from one individual to another… and they can have a sort of sex. Sexual reproduction – like that used by most animals and plants – involves at lease two individuals and normally these are called males and females. With this sort of reproduction you can start a population with just one bacterium. Then the two copies separate in the cell and the cell grows two new cell membranes (and two new cell walls) through its middle – effectively cutting the cell in half, to make two cells.īinary fission is asexual (the ‘a’ in front meaning without) reproduction, because both the daughter cells have exactly the same DNA as the original cell and only one cell is involved. First, the DNA in the cell makes a copy of itself. There is a little more to it than that though. The simplest form of bacterial reproduction is called binary fission.īasically, binary fission is where a bacterium grows to about twice the size of the smallest bacterium and splits in two. Still, it is worth remembering how quickly one bacteria can become many when it finds something it likes to eat. Which is why we aren’t swimming around in that soup of bacteria. ![]() ![]() In extreme conditions where there is very little food, or low temperatures it can take much longer still – which is good for us.Īlso, many things eat bacteria or cause them to die. In real life, a cell normally takes between 1 and 24 hours to reach maturity. But a mere three hours later, they would out weigh it 400 times.įortunately for us, bacteria never actually end up in a perfect soup. In 45 hours the bacteria would only weigh 78% of the weight of the earth. If this seems unbelievable, experiment with the maths. My old bacteriology teacher assures me that in 48 hours the total weight of all the bacterial offspring of just this one bacterium would weigh 400 times the weight of the planet earth! The numbers just keep doubling every twenty minutes and they get horrendously large. By the time you had morning coffee or recess at 10.40 am there would be 4.4 billion (that is 4.4 British Billions or 4.4 million million = 4,294,967,296 bacteria). If the first bacterium fell into a perfect soup at the stroke of midnight, there would be 2,097,152 of them by the time you woke up at 7.00 am. ![]() In another twenty minutes they become eight. They can then reproduce… and one becomes two. In optimal conditions, they can reach maturity in 20 minutes.
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