Sex or no sex?

There are generally two types of reproduction in nature: with and without sex. During sexual reproduction, the genetic material from two individuals is combined, and used to form a new organism. The sexless form of reproduction is called asexual reproduction.

Warp speed

A large percentage of microorganisms, the prokaryotes (those without a nucleus) reproduce asexually. Bacteria and archaea primarily reproduce using binary fission. One cell simply splits into two identical cells. If circumstances are right, some bacteria can split in just 20 minutes. After ten hours, one bacterium cell can divide into a billion bacteria cells. Micropia shows you binary fission in action.

So, bacteria can’t reproduce sexually, but they can exchange genetic information with each other. Using a pilus, two bacteria make contact with each other and exchange genetic material. This is called conjugation. Some bacteria simply take up DNA which is floating around in their environment. The exchangie and uptake of genetic material allows bacteria develop new characteristics. That way, they can adapt and survive in new environments.

More variety in sex

Eukaryote microbes can either reproduce sexually or asexually. Or both. An example of this is the nematode (Caenorhabditis elegans). C. elegans are either male or hermaphrodite – which means they possess both male and female sex organs. During sexual reproduction, a male and a hermaphrodite lay next to each other. The male introduces sperm and fertilises the eggs of the hermaphrodite. But the hermaphrodite can also fertilise itself.

Despite the ease of this asexual self-fertilisation, the hermaphrodite still prefers to be fertilised by a different male. This produces more offspring and more genetic variation in progeny. But it’s not easy: only 0.1% of all nematodes are male.

Spore shooters

Many fungi can also reproduce sexually and asexually. Fungi often reproduce using spores – a type of seeds that can be spread by wind or rain. If a spore lands in a good place, a new fungus grows.

Some fungi use special structures to spread spores, like mushrooms. Fungi from the genus Pilobolus use a very special method to spread their spores. They mostly grow on poop, and they shoot their spores out at high speeds. Watch the film to see what that looks like.

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Taking hostages

Viruses can’t reproduce on their own. They need a host cell in order to be able to do it. The virus infects a host cell and releases its genetic material into it. The genetic material is built into that of the host’s cell. In this way, the virus takes the host cell hostage and forces it to make new viruses. Eventually, the host cell bursts, and many ew viruses are released.