Welcome to WHAT BIOLOGISTS DO. These five page contain information on the science behind how biologists know what they know. From microscopes to DNA sequencing, scientists have technologies to measure and analyse almost anything they want. Each technique, however, can only give certain types of information and only by using lots of different methods can we know things for certain.
WHAT BIOLOGISTS DO
Biologists are interested in living things - that includes bacteria, fungi plants and animals. All of these living things are made of cells. Depending on the types of questions scientists want to ask (or what hypotheses they want to test) they will do their research in different ways.
Some scientists study the behaviour of animals in the wild. For example, a group at the University of Bath wanted to understand the mating behaviour of a particular bird, the snowy plover. In order to do this, they had to go to Mexico and hide (so as not to scare the birds) and look for nests. Once they found snowy polver nests, they made a note of the location as well as counted how many birds visited the nest.
I couldn't find a picture of a snowy plover so here is one of a penguin. One of the scientists from the University of Bath's favourite animal is penguins.
But what if you are a malaria scientist? These scientists don't have to go out to a country that has malaria to do their experiments; they can study the disease in their lab. This is because in the lab they can mimic what happens in the outside world. Malaria is a deadly disease that is caused by a tiny parasite called Plasmodium falciparum which can only survive in human blood or in mosquitos. This means that the parasite can be grown in the lab in human blood left over from hospitals or donated by enthusiastic scientists! As long as the parasite is kept at human body temperature (37 degrees) and is fed fresh blood every few days, it can grow in a lab for months without dying. This means scientists can learn about exactly how the parasite works -which can help make new anti-malarial drugs - all without having to use any animals or humans.
Cell culture = growing cells in the lab, outside of their natural environment
Media = (ie cell food) a liquid made of a mixture of nutrients and chemicals that keep cells alive
Blood samples in the lab
The malaria parasite can grow in blood, which humans can donate without too much of a problem (as long as you don't have a phobia of needles!). But what if you want to study other diseases, like cancer, dementia or heart disease? How can we study other bits of the human body like the brain, guts and bones, things which we can't just donate to a lab?
Answer: cell culture
Cell culture is the bread and butter of any cell biologist. In the same way that the malaria parasite can be grown in the lab by mimicking how it would in real life (i.e. in blood), any cell can be grown in the lab as long as the conditions are just like they would be in real life. This means it is possible to grow cells from humans such as a tumour that is extracted during an operation. Instead of just throwing away the tumour once it has been taken out of a patient, we can put it in a container, feed it with nutrients called media and grow it in the lab so we can learn more about the cancer. This can also be done for non-cancer things, like bits of skin.
Cells differ in how they are grown and can be grown in different containers:
Developmental biology = how organisms grow from a single cell into a whole animal/plant/anything
Organism = an animal, or a plant, or a fungi or bacteria. Can be made of many cells e.g. a fly or just one e.g. E. coli
As we know from THE CORE, there are many different types of cells. Things that happen in the human body, e.g. cancer, however, don't just happen in one specific cell type.
What if you want to study a disease or process that involves lots of different cell types or even the whole body? Traditionally, in fields of biology, such as developmental biology, whole organisms are used instead of cell culture. These are called model organisms. Although it wouldn't be possible to study a disease that only happens in humans in a model organism, there are lots of biological processes that are shared amongst living things. This means we can study lots of human diseases in mice for example. Model organisms are organisms that are easy to grow in the lab and have usually been used for a long time to help scientists understand basic biological things.
Here are some common model organisms and what they have taught us:
E. coli (a common bacteria)
How bacteria divide
How bacteria can share DNA
Making DNA and proteins
Drosophila (fruit flies)
S. cerevisiae (Baker's yeast)
How DNA breaks and is repaired
How cells divide and age
Mus musculus (mice)
Psychology and neurobiology
Metabolic diseases like obesity, diabetes and heart disease
Testing medicines to check they are safe and work
Model organisms like these and many more (fish, frogs, worms, the list goes on) have taught us a huge amount about ourselves.
What if (I promise this is the last what if) you want to study a human disease that involves not just one cell type? Scientists are figuring out they can grow cells in the lab not just in a plastic container, but in a way that makes them act more like they do in a human body. This also means we can reduce the need for animals. Post coming soon!
Biologists study living things, this makes experiments a bit more complicated! They have some options:
Studying animals in the wild e.g. snowy plovers in Mexico
Studying parasites in the lab e.g. malaria parasites in blood
Studying human cells in the lab e.g. cell culture in media
Studying model organisms in the lab e.g. flies