Cells can be found in many different shapes and sizes. Some cells, known as prokaryotes, don't have a nucleus or organelles. With hundreds of types of bacteria, each with unique features, and many different eukaryotic cells that can specialise in a specific function, it's important to have methods to study them. Different techniques are used depending on what we want to learn about a cell. One of the most well-known methods is cell microscopy. By examining cells and cell parts, we can gather information about them. This involves using different types of stains depending on the features of the cells. For example, different stains are used for fat cells than for muscle cells. Did you know that the biggest unicellular organism is an alga called Caulerpa taxifolia? Its cells can grow to an enormous 15 to 30 cm! Since most cells can't be seen with the naked eye, this is truly gigantic! Before discussing these methods, let's first cover some safe laboratory working techniques.

Safe laboratory working practices

Before you start working on an experiment, it's important to prepare and read the risk assessment, which outlines the potential hazards of the experiment. If you notice any damage to the equipment you're about to use, be sure to report it. Make sure you have all the personal protective equipment (PPE) required for the experiment. Depending on the nature of the experiment, PPE may include safety goggles, a laboratory coat, boots, face shields, and other items. When conducting the experiment, be sure to follow the correct procedure. In the event of an emergency, you must be able to quickly locate emergency eyewash stations, showers, and a first aid kit. You will be supervised by your teacher or a lab technician, who will advise you on these procedures. To ensure safety, avoid direct contact with potentially hazardous chemicals, don't eat or drink in the lab, wash your hands regularly, tie your hair back, and use relevant PPE. Your teacher will guide you through any other necessary steps and will carefully read over the experiment with you.

Cell biology lab techniques

Labs use many different techniques to study various cells, so let us take a closer look at some of them. First, we will briefly look at microscopy and how cell cultures work. If you want to learn more about microscopy, we have a whole article about it!

Cell microscopy

There are many different types of cell microscopy. The most notable are light microscopy and electron microscopy. Light microscopy is used to view tissues and cells, while electron microscopy is used to view cell organelles in detail. Within the realm of light microscopy, many subtypes are used to improve the resolution of light microscopes, such as working with fluorescent dyes and radioactive markers.

Growing cell cultures using the streaking technique

The most common cell cultures are microbial cultures, which are used to detect bacteria in a sample or replicate a specific bacteria. The streaking technique is the most popular way to grow distinct bacterial colonies. However, it's important to work in a sterile environment using an aseptic technique to prevent pathogen contamination.

To create an isolated culture of bacteria, you'll need an inoculation loop, a Bunsen burner (plus a lighter or match to ignite it), and an agar plate (or any other suitable sugar-based media). Start by turning on your Bunsen burner and adjusting the flame to blue. Next, sterilise the inoculation loop in the blue flame until it turns bright red. Allow it to cool. Then, pick up some of the isolated colony with the loop and streak around 3-4 times in a parallel motion to cover about a quarter of your petri dish. Put the loop under the flame again and let it cool. After that, extend the streaks on the plate into the next quarter of the dish. Repeat this process in the next two-quarters of the petri dish.

Techniques in cell and molecular biology

While cell biology looks at cells as a whole and their organelles, molecular biology looks at smaller parts within the cell, such as Chromosomes and DNA. Specific techniques are needed to find out more about these molecules. The main methods you should know are polymerase chain reactions (PCR) and gel electrophoresis.

Polymerase chain reaction (PCR)

The Polymerase Chain Reaction (PCR) technique is used to copy small fragments of DNA, allowing for further study or use in tests that detect DNA, such as Covid-19 PCR tests. To understand PCR, it's essential to understand DNA replication. The first step in PCR is DNA denaturation, which separates the DNA sequence into single strands. Next, DNA primers, nucleotides, and Taq polymerase (heat-stable) are added to the solution. The DNA primers attach to the target nucleotide sequence during the annealing step. In the elongation step, Taq polymerase binds to the DNA primers, and the strand is copied. This cycle is repeated, resulting in millions of DNA fragments. Taq polymerase is a heat-resistant enzyme widely used in PCR to replicate a specific DNA sequence. It's extracted from a heat-resistant bacteria called Thermus aquaticus. DNA primers are short, single-stranded DNA sequences that attach to the target nucleotide sequence during the annealing step. By using PCR, laboratory technicians can amplify small amounts of DNA to detect diseases, genetic disorders, and other applications.

Gel electrophoresis

Gel electrophoresis is a technique used to separate molecules by molecular size. It's commonly used to separate DNA, RNA, and proteins. In this technique, the molecules are placed in a gel that is subjected to electrical currents. The gel contains small pores that allow molecules to move through it. Smaller molecules will generally travel faster than larger ones because they can pass through the pores more easily. Gel electrophoresis is widely used in molecular biology research to distinguish between different lengths of DNA fragments. DNA fingerprinting is a common application of this technique, especially in criminal investigations, where it links the evidence to the suspect. The reason why there are different sizes of DNA fragments among people is that every person has multiple repeated sections on their DNA. The number of repeats varies from person to person. The repeated sections are cut out of the DNA through specific reactions. If we look at five sections of DNA between two people, one person may have more repeats in section 1, and person two might have more repeats in section 4.

By using gel electrophoresis to separate these fragments, scientists can identify unique patterns of DNA fragments that are specific to each individual. This technique has revolutionized criminal investigations and has become an essential tool in forensic science.

Methods of studying eukaryotic cell structure

Cells can be studied in various ways depending on the aspect to be studied. Eukaryotic cells, which are usually larger than prokaryotic cells, can be studied using light microscopy, where cells are placed between two glass/clear plastic slides and stained to accentuate specific organelles. Light microscopes can see larger organelles such as the nucleus, cytoplasm, and cell wall.

Organelles of interest can be isolated by breaking open the cell and isolating the different organelles for commercial use, a process called subcellular fractionation. Prokaryotes, such as bacteria, are often grown in a laboratory to be studied. They have high division rates, and the streaking technique is often used to grow isolated cultures of bacteria. Eukaryotic cells can also be grown in cell cultures, but this is more complicated since they do not replicate in the same way as prokaryotic cells. It takes more time for them to replicate. There are different methods used to study cells, and incorporating safe laboratory practices is essential before starting an experiment. The two most frequently used types of microscopy are light microscopy and electron microscopy. Light microscopes are often used in schools and universities to teach students. The polymerase chain reaction is used to determine the molecular weight of different lengths of DNA.

Methods of Studying Cells

What method is used to study eukaryotic cell structure?

The most well-known method of studying eukaryotic cells is through the light microscope. 

What is cell microscopy?

There are many different types of cell microscopy. The most notable are light microscopy and electron microscopy. Light microscopy is used to view tissues and cells, while electron microscopy is used to view cell organelles in detail. 

What are the techniques in cell biology?

There are many techniques, common ones are microscopy and cell cultures.

What is the study of the structure function and abnormalities of cells?

Microscopic anatomy.

What is the biggest unicellular organism?

An alga called Caulerpa taxifolia.

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